HomeMy WebLinkAboutAPA1756TR 161
Technical Report 161
SURVEY OF
ARCTIC AND SUBARCTIC
TEMPERATURE INVERSIONS
by
Michael A. Bilello
OCTOBER 1966
U.S. ARMY MATERIEL COMMAND
COLD REGIONS RESEARCH & ENGINEERING LABORATORY
HANOVER, NEW HAMPSHIRE
Technical Report 161
SURVEY OF
ARCTIC AND SUBARCTIC
TEMPERATURE INVERSIONS
by
Michael A. Bilello
OCTOBER 1966
U.S. ARMY MATERIEL COMMAND
COLD REGIONS RESEARCH & ENGINEERING LABORATORY
HANOVER, NEW HAMPSHIRE
DA Task IV014501852A02
Distribution of this document is unlimited.
ii
PREFACE
This study was conducted under the general supervision of Dr. R. W. Gerdel,
former Chief, Environmental Research Branch, and Dr. A. Assur, Chief Sci-
entist, USA CRREL.
The machine-tabulated data used in the survey were processed and prepared
at the Weather Bureau National Weather Records Center; Asheville, North
Carolina. The research was requested and funded by the Defense Atomic Sup-
port Agency under Nuciear Weapons Effects Research subtask number 02. 046.
The author wishes to thank Mr. Roy Bates for his assistance in the prepara-
tion of the tables.
USA CRREL is an Army Materiel Command laboratory.
iii
CONTENTS
Page
Preface------------------------------------------------------------ii
Summary----------------------------------------------------------iv
Introduction--------------------------------------------------------1
Selection of stations-----------------.,--------------------------------2
Description of data--------------------------------------------------2
Tabular presentation------------------------------------------------4
Graphical presentation of data----------------------------------------5
Discus sian of results------------------------------------------------5
Literature cited ----------------------------------------------------13
Appendix A. Typical Arctic temperature inversions --------------------31
ILLUSTRATIONS
Figure
1. Station map --------------------------------------------------3
2. Statistical summary of inversions with the base at the surface, Alert,
Canada-----------------------------------------------~----6
3. Statistical summary of inversions with the base above the surface,
Alert, Canada----------------------------------------------6
4. Frequency of inversion occurrence, in terms of thickness and tern-
perature gradient, for two 6-rnonth periods--------------------7
5. Inversions with base at the surface-----------------------------8
6. Inversions with base above the surface--------------------------9
7. Frequency of various inversion thicknesses----------------------10
8. Frequency of various inversion temperature gradients ------------11
9. Day-to-day variations in height of warmest temperature in the lower
Table
I.
II.
III.
IV.
atmosphere ------------------------------------------------14
TABLES
Period of record and elevation of stations covered in the survey ---
Statistical summary of inversions in which the base is at the surface
Statistical summary of inversions in which the base is above the
surface----------------------------------------------------
Frequency of inversion occurrence, in terms of thickness and tern-
perature gradient, for two 6-rnonth periods--------------------
2
15
19
23
iv
SUMMARY
This study provides a statistical analysis of available data on
Arctic and subarctic inversions, and includes data from locations
in Canada, Greenland, and Alaska. The analysis considers in-
versions with respect to frequency, base height, thickness, base
temperature, and temperature gradient.
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
by
Michael A. Bilello
Introduction
A temperature inversion is defined meteorologically as a layer of air in which
the temperature increases with altitude. As noted in the Glossary of Meteorology
( 1959), the principal characteristic of an inversion layer is its marked stability,
which allows very little turbulent exchange to occur within it.
Wexler (1936) points out that during clear, calm nights, the temperature of a
snow surface falls below the temperature of the air. He describes how the snow
surface radiates energy practically as a black body and receives, by conduction
from the snow and air and also by atmospheric radiation, less energy than it loses
through its own radiation; consequently, its temperature decreases.
In polar regions, inversions are observed throughout the year, but are usually
steeper during the cold period of the year than during the warm period. The bases
of these inversions are not always located at the earth's surface. When the layers
adjacent to the earth's surface are warmed, an inversion may still persist, but
the base then is located off the ground. The heights to which inversions extend
and the intensity of tem~~erature-increase-with-height vary from place to place and
from month to month.
The purpose of this study is to provide a statistical analysis of available data
on Arctic and subarctic inversions. The study includes data from locations in
Canada, Greenland, and Alaska, and the analysis considers inversions with re-
spect to frequency, base height, thickness, base temperature, and temperature
gradient.
A major study of this type was conducted by the U.S. Navy (1963). There-
sulting Marine Climatic Atlas of the World presents climatic data for 47 stations
throughout the North American Arctic and subarctic. Included are charts giving
monthly percentage-frequencies of three intensities of temperature inversion
within each of seven layers from the surface to 700 millibars. However, these
charts do not provide information on: l) the thickness of the inversion; 2) standard
deviation from the average base height or thickness; 3) temperature at the base of
the inversion. To provide this information the author has reanalyzed data for
some of the stations in the Navy survey, and included certain areas not covered
in the Atlas, such as central Alaska.
Wyatt (1952) notes that inversions in polar regions have also been studied by
Sverdrup ("Maud" Expedition to the Arctic Ocean), Flohn (Siberia), Wexler (Alaska),
and the German Expedition to the Antarctic in 1911-12. These studies consider
only short periods of record and do not provide detailed statistical information for
each month of the year.
In an investigation on the distribution of temperature lapse rates over the
Arctic regions, Putnins and Choate ( 1960) considered mean temperatures and the
following standard layers: surface to 850mb, 850-700 mb, 700-500 mb, and
500-300 mb. In the study, daily lapse rates observed during a 1950-51 Russian
expedition on drifting ice; mean monthly lapse rates for Fletcher's Ice Island
(T-3) observed during 1952-54; and mean seasonal lapse rates for one Iceland,
eight Greenland, and five Canadian stations are presented. Mean values on the
magnitude of inversions observed at these stations for the intervals noted above
also were included.
Recently, Vowinckel ( 1965) conducted a study on inversions over the Arctic
Ocean proper. Radiosonde data from North Pole stations 4, 6 and 7 and for 30
coastal stations surrounding the Arctic Ocean were used. He found slightly stable
2 SURVEY OF ARC TIC AND SUBARCTIC TEMPERATURE INVERSIONS
temperature gradients over the Arctic Ocean in summer changing to very strong
inversions by late winter. Unstable gradients predominated over the warm waters
of the Norwegian-Barents Sea. The most intense inversions were found over the
Beaufort Sea and northwest of the Canadian Archipelago.
In an informal, unofficial USA CRREL Research Note, data on some typical
inversions in the Arctic were compiled by the author. These data are appended
to this survey (Appendix A).
Selection of stations
A statistical analysis of inversions requires data from upper air soundings
made over a reasonable duration of time. Statistical computations on the bulk
data were made by computers at the Weather Records Center in Asheville, North
Carolina. Except for Thule, the stations used in this study had approximately 8
to 10 years of record available on punch cards. For Thule there was just over 5
years of record. The period of record for some stations was not continuous:
e. g., the record for Alert, Canada, is from September 1950 through December
1959 and contains occasional short gaps during the first twenty days of April 1952.
These variations have a negligible effect on the overall statistics because the
number of soundings, rather than the number of days, was considered in the com-
putations.
Although upper air soundings have been made in the arctic regions of Asia
and Europe, only a small portion of the data is available on punched cards. For
this reason the study was confined to stations in the Western Hemisphere.
The number of stations that could be studied with the allotted funds was deter-
mined by: 1) the format and extent of the statistical computations; and 2) the
number of cards used per station. Table I gives the name, elevation, and ;:>eriod
of record of each station in the survey. The location of each station is shown in
Figure 1. These stations were selected on the basis of geographical coverage,
length of record, and availability of punched cards. Also, an attempt was made
to include stations omitted in the Naval Marine Atlas.
Table I. Period of record and elevation of stations covered in the survey.
Station
Alert, Canada
Barrow, Alaska
Churchill, Canada
Clyde River, Canada
Coppermine, Canada
Coral Harbour, Canada
Fairbanks, Alaska
Mould Bay, Canada
Nome, Alaska
Thule, Greenland
Yakutat, Alaska
Description of data
Period of record
9 I 50 -
7 I 52 -
1 I 50 -
1 I 50 -
2155 -
1 I 50 -
4152 -
8150 -
7 I 52 -
1 I 50 -
7 I 50 -
8152 -
1 I 53 -
12159
10159
12159
41 54;
12159
21 52;
12159
12159
3161
12159
12159
12157
12161
Elevation (m)
62
7
35
3
9
53
133
15
4
37
9
The machine-tabulated data were divided into two sections, and each section
was divided into two parts.
The first section is a monthly tabulation of the number of upper-air soundings
taken and the number of inversions observed. Two types of inversions are listed:
1) those in which the base of the inversion is at the earth's surface; and 2) those
in which the base is above the surface. Subsequently, these inversions will be
Figure 1. Station map.
H z < M
:::0
(/l
H
0 z
(/l
4 SURVEY OF ARC TIC AND SUBARCTIC TEMPERATURE INVERSIONS
identified as type 1 and type 2, respectively. For this survey, any layer having
more than one degree (C) increase in temperature per kilometer was considered
to be an inversion layer (U.S. Weather Bureau, 1961). Statistical computations
for each month and each type of inversion were made. For type 1 the following
information was provided:
a. Average thickness of the inversion, in meters, and the standard
deviation.
b. Average increase in temperature with height (or temperature gradient),
in ° C per 100 meters, and the standard deviation.
c. Average temperature at the base of the inversion (i.e., earth's sur-
face) in °C.
Standard deviation was computed from the formula:
S =J n L;vZ -(L;v)Z
n (n-1)
where v =the observed values and n =the number of counts.
For inversions in which the base was above the surface (type 2), computations
a, b and c were made, and, in addition:
d. Average height of the base of the inversion, and the standard deviation.
Two upper soundings are normally made each day: one at 2400 and another at
1200 Greenwich Meridian Time. Unfortunately, only the 2400 GMT observations
were available on punch cards for all the stations except Nome and Fairbanks,
Alaska. The cost of punching the 1200 GMT data was too expensive to justify its
inclusion in the study. Since locations in high latitudes experience long periods of
light and dark, omission of diurnal variations is negligible. However, for the
purpose of noting diurnal variations at lower latitudes, statistical analyses of both
2400 and 1200 observations were conducted for Nome and Fairbanks, Alaska.
The second section of the machine-tabulated data gives the number of inver-
sions in terms of thickness and temperature difference from the base to the top
of the inversion; increments of 50 meters thickness and lC temperature difference
were used.
This second section was divided into two arbitrarily defined time periods:
1) the months November through April and 2) the months May through October.
For those stations located in the Arctic, the first period defines approximately
the months of continuous dark, and the second period the months of continuous
light. For stations at lower latitudes these periods define the relative cold and
warm months, respectively.
Tabular presentation
The data are presented here as Tables II, III and IV. The major portion of
this statistical survey consists of a set of these tables for each station studied.
Table II gives statistical summaries by month for inversions with the base at
the earth surface (type 1), including: number of soundings, number and frequency
of occurrence, average thickness and temperature gradient, and standard deviation
of thickness and temperature gradient. ·
Assuming that the observations on thickness and temperature gradient are
fairly symmetrical with respect to the mean (or average) value, the standard
deviation gives a measure of the range within which a large proportion of the re-
ports will be included. In a normal distribution the interval from the distance of
one standard deviation below the mean to the distance of one standard deviation
above the mean will include about 2/3 of the observations (Ezekiel and Fox, 1959).
SURVEY OF ARC TIC AND SUBARCTIC TEMPERATURE INVERSIONS 5
Since the lower limit of the inversion thickness in Table II is finite and the upper
limit unbounded, the data are probably not normally distributed. This means that
fewer than 2/3 of the observations can be expected to occur within the limits de-
fined by the standard deviation.
The average inversion temperature gradient (the rate of increase in tempera-
ture with height) is the mean of the gradients for all the inversions, assuming a
uniform increase in temperature from the base to the top for each individual in-
version.
Table III gives the same information for type 2 inversions, with two more
columns giving the average height of the base of the inversion above the surface
and the standard deviation of the base height. Base height plus thickness gives
the average height of the top of the inversion.
Table IV gives the frequency of inversion occurrence in terms of various
thicknesses and temperature gradients.
The machine data were analyzed in terms of 50-meter increments of inversion
thickness, but are presented in Table IV in increments of 200 meters.
The breakdown given in Table IV is somewhat detailed. The format, however,
allows the user to combine categories as required.
Graphical presentation of data
Types of figures adaptable to graphical presentation of the inversion data are
shown in Figures 2, 3 and 4. The data for Alert have been presented in graphical
form as an example.
Note that the sloped lines in Figures 2C and 3C extend to 500 meters. This
level was arbitrarily selected and does not indicate specific inversion thicknesses.
To compute temperature gradient in terms of oc /100 meters, subtract the tem-
perature at 500 meters from that at the base and divide by five.
Discussion of results
Seasonal variations. Inspection of the data in Tables II and III shows differ-
ences in inversion frequency and physical characteristics between the six cold
months (November through April) and the six warm months (May through October).
The outstanding difference is the variation in inversion thickness; inversions
during the cold months are deeper (extend to a greater height) than those observed
Addendum -USA CRREL Technical Report 161
On page 5, next-to-last paragraph, add:
V""\l,,,f-":l.t-
In Figures 5 and 6 only the 2400 Z data were used in the tabulations
for Fairbanks and Nome.
to a o-mCJillll pt:J.~UU.o ~H~ -·---o-
"''"e
Jnths.
r
~r-
.rm''
Lfy
re
.gh
•ccur
.rd.
·ing
:y.
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS 5
Since the lower limit of the inversion thickness in Table II is finite and the upper
limit unbounded, the data are probably not normally distributed. This means that
fewer than Z/3 of the observations can be expected to occur within the limits de-
fined by the standard deviation.
The average inversion temperature gradient (the rate of increase in tempera-
ture with height) is the mean of the gradients for all the inversions, assuming a
uniform increase in temperature from the base to the top for each individual in-
version.
Table III gives the same information for type Z inversions, with two more
columns giving the average height of the base of the inversion above the surface
and the standard deviation of the base height. Base height plus thickness gives
the average height of the top of the inversion.
Table IV gives the frequency of inversion occurrence in terms of various
thicknesses and temperature gradients.
The machine data were analyzed in terms of 50-meter increments of inversion
thickness, but are presented in Table IV in increments of ZOO meters.
The breakdown given in Table IV is somewhat detailed. The format, however,
allows the user to combine categories as required.
Graphical presentation of data
Types of figures adaptable to graphical presentation of the inversion data are
shown in Figures Z, 3 and 4. The data for Alert have been presented in graphical
form as an example.
Note that the sloped lines in Figures ZC and 3C extend to 500 meters. This
level was arbitrarily selected and does not indicate specific inversion thicknesses.
To compute temperature gradient in terms of oC/100 meters, subtract the tem-
perature at 500 meters from that at the base and divide by five.
Discussion of results
Seasonal variations. Inspection of the data in Tables II and III shows differ-
ences in inversion frequency and physical characteristics between the six cold
months (November through April) and the six warm months (May through October).
The outstanding difference is the variation in inversion thickness; inversions
during the cold months are deeper (extend to a greater height) than those observed
in summer. Subarctic locations under a maritime influence, e. g. Yakutat, are
an exception to the rule.
Type l inversions occur more frequently during cold rather than warm months.
In general, the opposite is true for type Z inversions.
Temperature gradients (inversion steepness) at most locations are greater
during the cold period of the year. This is true for both type l and type 2 inver-
sions.
It is difficult to make a precise separation of the year into "cold" and "warm"
6-month periods, but the physical characteristics of the inversions change
sufficiently between April and May and between October and November to justify
a separation at these times.
Regional variations. Regional variations in inversion characteristics were
analyzed using the seasonal break. The results are shown in Figures 5 through
8.
From Figure 5 it can be seen that throughout the year type l inversions occur
most frequently at Alert and Coral Harbour and decrease in frequency westward.
Note that two frequencies (in percent) are shown for each station, each referring
to a 6-month period. The average of the two values gives the annual frequency.
100
;e
!.. 80
>-(.) 60 z
LoJ
::::> 40
0
LoJ
0:: u.. 20
0
800
in
0::
LoJ
~
LoJ
::::e
~
:I:
(!)
~ SFC
:I:
I •
I I
JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.
o.FREQUENCY OF OCCURRENCE
FEB APR
b.
_, ..
"-----"""'
''--"'-STANDARD
----DEVIATION
JUNE AUG OCT. DEC.
600r--.---.--.---r--.---r--.---.--.---r--.---.---r--,
in
0::
LoJ
~
LoJ 400
::::e
(/)
(/)
LoJ z 200 ::.::
(.)
:I:
~ 01 ,, -, ., I I I I ." WI I
I I I I I I I I I I I I I I
. -40 -32 -24
c. AVERAGE TEMPERATURE AT SURFACE
AVERAGE TEMP. GRADIENT
16 c
Figure 2. Statistical summary of inversions with
the base at the surface, Alert, Canada.
i" ~ I I I I I I I I I I I I I
U.. JAN FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.
(/) a::
o.FREQUENCY OF OCCURRENCE
12oo~.....,....-,..----r--.----r-r-r-ll--r-rll
LoJ ~ BOO
LoJ
::::e
LoJ
:I:
FEB. APR. JUNE AUG. OCT DEC.
SFCL--J~A~N.~L_~M~AR~.~~M~A~Y~~~J~U~LY~L_~SE~P~T~._L~NLOV~.~--~
b. AVERAGE HEIGHT OF BASE AND TOP OF INVERSION
600r-~---.--~--r--.---r--,---.-~r-~--~
(/)
a::
LoJ
~ w 400
::::e
(/)
(/) w z 200
:.:: u
:I:
~ Ol I, I I u I I I I I ., I
-8 0 8 c
c. AVERAGE TEMPERATURE AT BASE
AND AVERAGE TEMPERATURE GRADIENT
Figure 3. Statistical summary ofinversions with
the base above the surface, Alert, Canada.
0'
Vl
c::: :;o
< M
>..:::
0
t-Ij
;:r> :;o
(l
>-:l
H
(l
;:r> z
t::1
(/)
c:::
~
(l
>-:l
H
(l
>-:l
M
~
'"0
M :;o
;:r>
>-:l
c::: :;o
M
H z < M :;o
(/)
H
0 z
(/)
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS 7
~1000
(/)
a:: w 800
I-w
:!:
600
(/)
(/)
w z
~ 400
u
:X:
I-
200
A) INVERSION THICKNESSES WERE GROUPED IN INCREMENTS OF 200 METERS
B)
C)
RATES OF TEMPERATURE INCREASE PER 100 METERS INCREASE IN
HEIGHT WERE GROUPED AS FOLLOWS:
O.lto<I.0°C
3.0° c 1.0 to< 3.0°C
TWO PERIODS WERE CONSIDERED: NOVEMBER THROUGH APRIL AND MAY THROUGH OCTOBER
NOVEMBER THROUGH APRIL
1635 SOUNDINGS ( 10 Years of record)
1598 INVERSIONS (Frequency of occurrence= 98 °/0 )
1357 WITH BASE AT SURFACE (Frequency= 83°/0 )
241 WITH BASE ABOVE SURFACE (Frequency= 15%)
I'"= II% (15.5% minus 4.5%) of all soundmgs taken durmg
10 20 30
November through Apnl recorded thtclrness of < 200 meters
and temperature 1ncrease of 1.0 to< 3.0°C/IOO meters.
FREQUENCY OF OCCURRENCE (%)
~1000
(/)
a:: w 800
1-w
:!:
(/)
(/)
w z
600
~ 400 u
:X:
I-
200
0 o~--~--I~0--~--~2~0--~--~30
FREQUENCY OF OCCURRENCE (%)
MAY THROUGH OCTOBER
1649 SOUNDINGS ( 10 Years of record)
1381 INVERSIONS (Frequency of occurrence= 84°/0 )
743 WITH BASE AT SURFACE (Frequency= 45 °/0 )
638 WITH BASE ABOVE SURFACE (Frequency= 39°/0 )
Figure 4. Frequency of inversion occurrence, in terms of thickness and tempera-
ture gradient, for two 6-month periods.
LEGEND
Nov. -Apr.
44
560
1.6
May-Oct.
28
320
1.4
Frequency of occurrence (o/o) f>
based on the 6-month period. J.t'
Average inversion thickness.
Average temperature gradient.
Figure 5. Inversions with base at the surface.
00
C/l
c:::
~ < M
>-<:
0
f-Ij
~
~
0
"":]
H
0
~
t:J
C/l
c:::
IJ:j
~
~
0
"":]
H
0
"":]
M
~
f-(J
M
~
~
"":]
c:::
~
M
H z < M
~
C/l
H
0 z
C/l
LEGEND
Nov. -Apr.
51
530
( 480)
1.4
May-Oct.
41 Frequency of occurrence (o/o) p
based on the 6-month period.
330
( 660)
1.2
Avg inversion thickness (m).
Avg height of base above sfc (m)
Average temperature gradient
(°C/l00m)
Figure 6. Inversions with base above the surface.
(/) c: ::u <:
M
~
0
"'1
> ::u
0
j
0
> z
tJ
(/) c:
l:d
;:t:> ::u
0
f-3
H
0
f-3
M
~
1:1
M ::u > f-3 c: ::u
M
H z <:
M ::u
(/)
H
0 z
(/)
"'
LEGEND
Frequency of occurrence (o/o) based on the
following 6-month periods:
Nov. -Apr.
44
30
22
May-Oct.
51
14
4
( 001 to 399 m thick)
( 400 to 799 m thick)
( ~ 800 m thick)
p
Figure 7. Frequency of various inversion thicknesses.
......
0
(/) c:
::0 < M
...::
0
f-rj
~
::0 ' () t-3
H
()
~ z
t)
(/) c:
tJj
~
::0
()
t-3
H
()
t-3
M
~
"d
M
::0
~
t-3 c:
::0
M
H z < M
::0
(/)
H
0 z
(/)
LEGEND
Frequency of occurrence ( o/o) based on the
following 6-month periods:
Nov. -Apr. May-Oct.
41
46
9
38
26
5
0. 1 to < 1. 0°C/100 meters.
1.0 to< 3.0°C/100 meters.
> 3.0°C/100 meters.
p
41
46
9
Figure 8. Frequency of various inversion temperature gradients.
'
(fJ c:
!:U
<:
M
><:
0
t-rj
;:t>
!:U
()
1--:l
H
()
;:t> z
tj
(fJ c:
IJj
;:t>
!:U
()
1--:l
H
()
1--:l
M
~
1:J
M
!:U
;:t>
1--:l c:
!:U
M
H z <:
M
!:U
(fJ
H
0 z
(fJ
..... .....
12 SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
During the cold months the thickness of type 1 inversions varies to some ex-
tent from place to place. During the summer months the thicknesses are regionally
uniform, except at Fairbanks, where shallow surface inversions are observed.
Average temperature gradients for type 1 inversions also vary from pl3.ce
to place during the cold months, ranging from 1. 0 to 2. 5C I 1OOm. During the
warm months this variation is less marked, 0. 6 to 1. 4C/100m. In the study on
typical Arctic inversions (App. A) it was found that extremely steep surface in-
versions occur on the Greenland ice sheet during the winter months. An observa-
tion made on 20 December 1949 at Station Eismitte in central Greenland, at
latitude 70° N, showed a temperature increase of 29. 4C in 350m.
From Figure 6 we find that, during the winter months, type 2 inversions are
least common at Thule and Alert and generally increase in frequency to the south
and west. Yakutat's climatic regime again makes this station an exception to the
rule. During the summer months, variations in frequency of occurrence of type
2 inversions do not follow any geographical pattern.
Thicknesses of type 2 inversions, like those of type 1, vary from place to
place during the cold period and in general are regionally uniform during the
warm period. Some regional variation in average base heights occurs during each
seasonal period. At all locations except Yakutat, average heights are greatest
during the summer months, especially in interior Alaska. Examination of Table
Ill reveals a notable phenomenon at many locations - a definite increase in base
heights during September and October. This phenomenon, however, is not always
consistent. At Alert, for example, it is only evident during September; and at
Fairbanks, only during the 1200 Z observations (Table IIIB).
Temperature gradients of type 2 inversions show little seasonal and regional
variation. The average range f::>r all locations during both seasons is 0. 7 to
1. 6CI lOOm.
Regional variation of frequency of occurrence for three categories of inversion
thickness (001 to 399m, 400 to 799 m, and> 800 m) is shown in Figure 7. The
frequencies are obtained from Table IV. Inversions less than 400 m thick pre-
dominate during the warm months. Inversions thicker than 800 m are observed
much more frequently in winter than in summer, and at some stations (Barrow,
Mould Bay and Coppermine) they actually occur more often than either of the other
two categories.
Figure 8 gives frequency of occurrence of three categories of inversion tem-
perature gradients (also from Table IV). Temperature gradients of 0. 1 to<
1. OCI 100m predominate during the warm months. In winter, inversions are
much steeper, as indicated by the marked increase in frequencies for the cate-
gories above 1. OC I 100m.
Diurnal variations. Data on two observations per day were available for
Fairbanks and Nome, Alaska, only. Nome time is 11 hours earlier, and Fair-
banks is 10 hours earlier than Greenwich Meridian Time. This means that the
2400 Z observation is made at 1300 local time in Nome and at 1400 in Fairbanks,
and the 1200 Z observation is made at 0100 and 0200 local time in Nome and
Fairbanks respectively. These times are given to show how the release time for
the upper air soundings varies from east to west. Therefore, attempts to asso-
ciate diurnal variations between locations longitudinally distant from each other
are not possible.
Inspection of the data for Fairbanks and Nome shows some diurnal variations
with respect to seasons. For example, for type 1 inversi:::ms, frequency, height,
and temperature gradient (Table IIA) show seasonal variations for the 2400 Z
observation, but only temperature gradient varies (Table liB) seasonally for the
1200 Z observation. For type 2 inversions (Table IliA), height of base, thickness,
and temperature gradient show seasonal variations for the 2400 Z observation at
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS l3
Fairbanks only, whereas only thickness shows seasonal variation for the 1200 Z
observation (Table IIIB). Almost no seasonal variations are noted for type 2
inversions at Nome for either observation. This absence is probably due to
•naritime influence. Apparently the Pacific Ocean cools the lower atmosphere
during summer and warms it during winter. This maritime effect at Nome is
further indicated by the relatively narrow range in inversion base temperatures
noted in column 7 of Tables liB, IliA, and IIIB.
On a year-round basis, type 1 inversions for both stations are more frequent
and steeper (although not necessarily deeper) during the 1200 Z observation. This
may be attributed to nighttime radiational heat loss.
Type 2 inversions, on an annual basis, occur only slightly more often during
the 2400 Z observation than at 1200 Z; and, except for base heights at Fairbanks,
few diurnal variations are found at the stations. At Fairbanks the average base
height during June, July and August is almost twice as high during the day as at
night.
The diurnal variations noted at these stations indicate that two observations
per day are required at stations below the Arctic Circle. For the purposes of
inversion studies, it would also be beneficial if these observations were made at
the time of local maximum and minimum daily temperatures rather than according
to Greenwich Meridian Time.
Finally, the day-to-day variations must be considered. Figure 9 is an
excerpt from Wyatt's ( 1951) study on daily variations in Arctic inversions. The
temperatures from the surface to 300m for each day are indicated by 5C iso-
therms (thin lines). The heavy line connects the warmest points on the successive
sounding curves and thus shows the daily variations in the height of the inversion.
The great day-to-day variation in the height of the inversion is immediately
evident from these curves. Attempts to predict such variations on a day-to-day
basis obviously would be difficult; therefore a statistical study such as the one
given here is the next best prognostic approach.
LITERATURE CITED
Ezekiel, M. and Fox, K. A. ( 1959) Methods of correlation and regression analysis.
New York: John Wiley and Sons, Inc., 3rd ed.
Huschke, R. E. (Editor) (1959} Glossary of meteorology. Boston, Massachusetts:
American Meteorological Society.
Putnins, P. and Choate, M. ( 1960} The distribution of temperature lapse rates
over the Arctic region, U.S. Weather Bureau, Quarterly Report,
February-April. U.S. Army Signal Research and Development Labora-
tory, Fort Monmouth, New Jersey.
U.S. Navy ( 1963) Marine climatic atlas of the world, Vol. VI, Arctic Ocean,
Chief of Naval Operations, NAVWEPS 50-lC-533.
U.S. Weather Bureau (1957, 1960, 1961} Reference manuals, Office of Climatol-
ogy, National Weather Records Center, Reference manuals for radiosonde
card decks 542, 544, 545, 505 and 524.
Vowinckel, E. ( 1965) The inversion over the polar ocean, McGill University
Publication in Meteorology No. 72.
Wexler, H. (1936} Cooling in the lower atmosphere and the structure of polar
continental air, U.S. Weather Bureau, Monthly Weather Review,
April, p. 122-136.
14 SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
LITERATURE CITED (Cont 1 d)
Wyatt, Lt. Col. W.H. (1951) Interesting variations in the arctic inversion, U.S.
Air Force, Air Weather Service Bulletin, November, 1952, p. 58-60.
Based on paper presented at the Washington, D. C. meeting of the
American Geophysical Union, 1 May 1951.
3000
_; 2500
vi
2
: 2000 .. ..
~ 1500
!:
~ 1000
~ .. .... ...
....
,.;
"' "' 0: .. ,_ ..
"' !:
z
0 ;:::
~ ... .... ...
500
3000
2500
2000
1500
1000
-tl -11 -e ·tO
If
·~ ...
...
-... ....
15 20
POINT BARROW, ALASKA
JANUARY 1949 (1500Z)
25 30
3000
2500
2000
1500
1000
500
3000
2500
2000
500 -~::~~
s~~:~EL-··~~~-~·~~--~._~~~~~~~~~~~~~~~~~~~~~~~~~~~
...i
.,;
2
"' a: .. ....
~
!:
z
0
~ .. .... ...
88M I 10 15 20
NORMAN WELLS, CANADA
JANUARY 1949 (1500Z)
CHURCHILL , CANADA
JANUARY 1949 (1500Z)
25 30
3000
2500
1500
1000
500
--LEV[L til __,.IT Tt .. [RAT\111
IN THE LOWEW ATMOSPMJtE
--ISOTHERMS I°CI
Figure 9. Day-to-day variations in height of warmest temperature in the lower
atmosphere. (From W. H. Wyatt, 1951)
SURVEY OF ARC TIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table II. Statistical summary of inversions in which the base is at the surface.
z
NUmber of
Month soundings
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
274
251
262
246
276
247
Z77
zn
275
302
295
307
216
195
187
181
217
207
248
245
238
248
210
217
300
275
301
287
301
298
306
300
289
305
279
289
Number of
inversions
(with base
at sfc}
223
217
234
200
121
80
78
108
165
191
224
259
134
97
76
47
4
25
50
32
39
67
80
123
155
148
157
109
79
81
108
98
83
58
n
130
3a*
Frequency of
occurrence
00
5
Average
thickness
~
Sat 6 6at
Standard Avg temp Standard
deviation gradient deviation
("C/lOOm)
Alert, Canada (~1 0-yr <record)
81
86
89
81
44
32
28
40
60
63
76
84
550
580
61}0
610
490
310
310
330
370
470
460
590
480
440
470
490
390
220
180
180
360
390
390
490
Barrow, Alaska ("'8-yr record)
62
50
41
26
2
12
20
13
16
27
38
57
880
990
820
540
290
350
350
280
240
330
530
790
600
580
450
400
140
210
zoo
zoo
260
310
430
550
Churchill, Canada, (~I 0-yr record)
52
54
52
38
26
27
35
33
29
19
26
45
690
670
520
420
420
330
310
280
230
370
410
660
480
470
440
290
270
zoo
zoo
170
140
270
270
430
z. 1
Z. I
Z. I
1.8
1.3
1.2
1.4
1.2
1.7
1.8
2.0
1.9
2.0
1.6
1.4
1.6
0.7
1.3
1.2
0.9
z.o
1.9
1.7
1.8
1.6
1.5
1.8
1.4
1.5
1.5
1.1
1.3
1.2
1.6
1.7
1.4
1.8
I. 8
1.6
1.8
1. 3
1.1
1.2
1.2
1.7
1.7
1.8
1.7
1.6
1.5
1.2
1.3
0.7
0.8
0.9
0.9
z.o
1. 7
1.4
1.8
1.6
1.4
1.7
1.3
1. 5
1.5
0.9
1.3
1.1
1.4
1.7
1.0
7
Avg temp
at base
~
-32
-34
-34
-25
-14
0
+ 5
+ 1
-I 0
-21
-26
-30
-28
-30
-26
-14
-2
+ 4
+ 6
+ 6
+ z
-10
-22
-28
-30
-27
-19
- 8
-I
+ 8
tl4
tl4
+ 8
+ z
-14
-24
* 3.a is the frequency of occurrence for inversions in which the base is at the surface (column 3 /column Z).
Sa and 6a are standard deviations for the data given in columns 5 and 6, respectively.
15
16 SURVEY OF ARC TIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table II (Cont'd). Statistical summary of inversions in which the base is at the surface.
Month
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
Arpil
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
()ct
Nov
Dec
2
Number of
soundings
260
250
288
287
237
263
254
259
241
267
253
261
296
273
272
298
306
286
305
284
269
276
261
293
269
245
271
257
277
261
265
300
228
291
290
290
3
Number of
inversions
(with base
at sf c)
158
174
216
181
74
59
75
70
41
55
117
!58
164
178
169
141
82
93
92
76
67
67
121
182
231
210
234
187
99
59
58
75
46
119
219
239
3a*
Frequency of
occurrence
(%)
5
Average
thickness
(m)
Sa
Standard
deviation
Clyde River, Canada (~9-yr record)
61
70
75
63
31
22
30
27
17
21
46
61
450
470
560
390
330
380
340
340
340
320
410
520
370
380
470
320
250
250
190
180
220
190
320
458
Coppermine, Canada (~10-yr record)
55 840 590
65
62
47
27
33
30
27
25
24
46
62
910
840
630
410
400
380
340
280
400
650
790
540
510
410
220
210
200
140
140
280
440
460
Coral Harbour, Canada (~9-yr record)
86
86
86
73
36
23
22
25
20
41
76
82
520
520
560
460
350
370
310
250
270
340
400
480
400
410
400
330
290
230
ISO
200
190
300
270
340
6 6a
Avg temp Standard
gradient deviation
("C/IOOm)
1.6
2,2
2.0
2.2
1.4
0.9
1.0
1.0
o. 8
1.1
1.4
1.7
1.1
1.0
1.0
0,8
0.8
1.3
1.4
1.1
0.8
0.8
1.0
1.1
2.5
2.3
2. 0
1.7
1.1
1.0
1.0
1.2
1.0
1.7
1.9
2.3
1.3
1.9
1.7
1.8
1.4
0. 9
1.0
o. 9
o. 7
1.1
1.2
1.5
1.1
0.5
0.7
o. 6
0.6
1.1
1.4
0.9
0.7
0.6
0. 7
0.9
2.4
2.2
1.9
1.7
o. 9
0. 8
0.8
1.2
o. 9
1.7
1.7
2.2
7
Avg temp
at base
("C)
-29
-30
-28
-21
- 9
+ 3
+ 6
+ 5
- I
- 8
-20
-26
-32
-33
-27
-16
- 3
+ 5
+10
+12
+ 5
- 8
-22
-28
-31
-31
-25
-15
- 8
+ 3
+10
+ 8
+ 2
-12
-20
-27
* 3a is the frequency of occurrence for inversions in which the base is at the surface (column 3/colurnn Z).
t Sa and 6a are standard deviations for the data given in columns 5 and 6, respectively.
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table II (Cont 1d}. Statistical summary of inversions in which the base is at the surface.
2
Number of
Month soundings
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
299
269
30!
260
303
296
3~9
305
293
298
293
305
133
137
!52
148
!53
149
!55
179
172
"169
170
180
276
252
277
27J
270
269
277
278
269
277
268
278
3
Number of
inversions
(with base
at sfc}
215
221
251
144
39
24
62
48
62
141
!86
222
97
103
!25
99
25
21
!8
35
56
89
110
150
170
101
42
18
10
4
4
2
15
73
!18
154
3a* Sat 6 6at
Frequency of
occurrence
Average
thickness
Standard Avg temp Standard
deviation gradient deviation
00 ~
Mould Bay, Canada (~I 0-yr record)
72
82
83
55
13
8
20
16
21
47
63
73
840
800
860
690
470
430
320
410
440
490
590
710
480
450
450
350
300
290
200
270
300
310
360
400
Thule, Greenland (~5-yr record)
73
75
82
67
16
!4
12
20
33
53
65
83
280
340
330
350
220
370
270
300
200
210
250
290
250
280
300
320
!50
!50
110
180
140
170
240
260
Yakutat, Alaska (~9-yr record)
62
40
15
7
4
6
26
44
55
210
2!0
160
210
150
330
450
170
270
180
!80
190
160
170
90
!60
60
130
170
70
120
90
90
120
(•c /! OOm)
1.7
1.5
1.6
1.2
1.0
0.7
1.1
0.8
!.I
1.3
1.5
1.5
2.5
2.8
2.6
2.2
0.8
l.O
1.2
1.0
1.0
2.2
2.4
2.6
2. I
1.2
0.8
0. 7
0.4
0.6
0.5
0. 3
o. 5
1.1
2.0
2.2
1.0
0.9
1.0
0.8
1.0
o. 6
0.8
0. 6
0.7
1.0
0. 9
0.8
1.8
2.8
2.6
2. I
0.8
0. 7
1.2
0. 9
0.9
1.8
!.8
2.6
2. I
1.0
0.5
0.6
0.4
0. 3
0. 3
0. I
0. 5
0.8
1.8
2.2
7
Avg temp
at base
-35
-37
-33
-23
-12
+ 4
+ 6
+ 5
- 7
-18
-27
-32
-25
-26
-26
-17
- 7
+ 4
+ 7
+ 5
- 3
-II
-20
-23
- 3
-2
+ l
+ 5
+ 8
+14
+18
+14
+II
+ 5
- 3
* 3a is the frequency of occurrence for inversions in which the base is at the surface (column 3/cobmn 2).
t Sa and 6a are standard deviations for the data given in columns 5 and 6, respectively.
17
18 SURVEY OF ARC TIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table Ila. Statistical summary of inversions in which the base is at the surface (2400 Z observations).
Month
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
2
Number of
soundings
277
253
279
240
248
239
279
279
270
279
271
279
275
252
276
270
279
267
310
3!0
300
31)
297
308
Number of
inversions
(with base
at sf c)
224
142
84
15
0
2
4
2
14
78
179
230
164
138
76
36
44
45
27
6
38
127
!86
3a* 5 Sat 6 6at
Frequency of
occurrence
Average
thickness
(m)
Standard Avg temp Standard
deviation gradient deviation
(%)
Fairbanks, Alaska (~9-yr record)
81 690 500
56
30
6
5
28
66
82
480
190
120
150
180
170
130
230
440
680
410
180
50
II 0
80
!0
60
220
360
500
Nome, Alaska (~9-yr record)
60
55
28
13
16
17
9
2
2
12
43
60
430
370
380
340
190
250
300
400
!20
140
240
330
420
360
340
330
II 0
!70
230
180
60
60
230
32.0
("C/IOOm)
2.6
1.8
1.3
0.8
1.1
0. 6
o. 7
0. 7
1.4
2.6
2.6
2. 3
1.9
1.0
0.8
1.5
1.3
1.3
0.4
0.4
1.0
1.9
3 0 3
2.3
1.5
1.3
0.6
0. 7
0.2
0. 7
o. 5
1.4
2. 6
z.. 5
2.2
1.9
l.O
0.8
1.5
1.3
1.3
0.4
0. 3
1.0
1.9
3.3
7
Avg temp
at base
("C)
-23
-17
-6
+ 2.
+16
+2.0
+17
+12
0
-14
-2.3
-16
-16
-13
-I
+ 5
+I 0
+13
+15
+ 7
-2.
-10
-19
Table IIb. Statistical summary of inversions in which the base is at the surface (1200 z observations).
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
2.77
254
2.79
2.39
248
239
2.80
2.78
269
279
2.72
2.78
2.32
2.10
2.39
191
179
149
173
193
191
186
2.!1
2.2.9
Fairbanks, Alaska (~9-yr
84 640
83
86
8,)
72
62.
62
69
71
67
78
82
560
420
310
240
280
320
310
290
350
500
6!0
record)
480
460
340
250
140
130
170
140
160
280
4!0
490
3.4
3. 0
3.0
1.9
1.5
1.4
1.3
1.3
1.5
2. I
2.7
3.2
3.2
2.8
2.9
1.7
1.5
l.Z.
1.1
l.O
1.4
2.0
2. 6
3.2
-25
-22
-18
-5
+ 5
+II
+II
+ 9
+ 3
-7
-!6
-24
* 3a is the frequency of occurrence for inversions in which the base is at the surface (column 3/column 2).
t Sa and 6a are standard deviations for the data given in columns 5 and 6, respectively.
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table IIb (Cont'd). Statistical summary of inversions in which the base is at the surface (12.00 Z observations).
2. 3 3a* 5 Sat 6 6at 7
Number of
inversions
(with base
Frequency of
occurrence
Average
thickness
Standard Avg temp Standard Avgtemp
at base Number of
soundings
deviation gradient deviation
Month
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
2.75
2.53
2.75
2.69
2.78
2.69
310
310
30,J
309
2.96
308
at sfc}
161
164
169
165
161
138
12.6
116
12.8
ISO
146
184
00 ~
Nome, Alaska (~9-yr record)
59
65
61
61
58
51
41
37
43
49
49
60
450
380
410
32.0
2.2.0
2.8"0
300
2.00
180
170
2.00
340
440
360
400
300
130
2.10
2.2.0
140
130
140
170
330
(•c/lOOm)
2..7
2..8
3. 0
2..9
2..0
1.8
1.7
1.8
2..1
2..3
2..4
3.3
2..7
2..8
3.0
2..9
1.8
1.5
1.4
1.4
2..1
2..3
2..4
3. 3
w
-18
-18
-17
-10
+ 2.
+ 7
+ 8
+ 8
+ 3
- 4
-10
-19
* 3a is the frequency of occurrence for inversions in which the base is at the surface (column 3/colurnn Z).
t 5a and 6a are standard deviations for the data given in columns 5 and 6, respectively.
Month
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Table III. Statistical summary of inversions in which the base is above the surface.
2. 3a* 4 4at 5 Sat
Number of Avgheight
inversions Frequency of of base
Number of (with base occurrence above sfc
Standard Average Standard
deviation thickness deviation
(m)
soundings above sfc) ('l'o) (m)
2.74
2.51
2.62.
2.46
2.76
2.47
2.77
2.72.
2.75
302.
2.95
307
2.16
195
187
181
2.17
2.07
2.48
2.45
2.38
2.48
2.10
2.17
44
2.9
2.2.
38
12.3
12.5
12.0
101
76
93
65
43
73
95
108
12.6
2.06
161
157
156
134
133
12.7
90
16
12.
8
15
45
51
43
37
2.8
31
2.2.
14
34
49
58
70
95
78
63
64
56
54
60
41
Alert, Canada (~I 0-yr record)
52.0 350 440
42.0
440
380
470
450
450
550
640
52.0
510
42.0
300
2.50
2.50
360
340
340
360
410
310
2.90
2.10
430
370
480
440
360
340
32.0
400
500
410
470
Barrow, Alas~a (""8-yr record)
340
2.90
2.30
300
42.0
340
310
400
590
580
400
330
2.50
180
150
2.50
2.30
2.2.0
300
2.60
330
350
2.50
2.10
780
870
840
660
550
480
480
430
380
390
560
640
350
310
2.50
440
300
2.30
2.00
2.70
2.90
400
32.0
370
450
550
430
42.0
350
2.60
310
2.60
2.30
2.60
410
42.0
6
Avgtemp
gradient
(•ctioo
m}
1.4
1.2.
1.4
1.2.
1.4
1.2.
1.0
1.0
0.8
1.2.
1.4
1.3
1.4
1.5
1.5
1.5
1.5
1.7
1.5
1.2.
1.1
1.4
l. 6
1.6
6at 7
Standard Avg temp
deviation at base
1.1
0.9
0.8
o. 9
1.4
1.2.
1.0
1. 0
0. 6
1.2.
1.2.
l. 0
1.1
1.2.
1.2.
1.4
1.2.
1.3
1.5
1.1
1.1
1.2.
1.3
1.6
(•c)
-32.
-30
-31
-2.5
-14
- 5
- I
- 3
-11
-2.0
-2.4
-2.9
-2.6
-30
-2.7
-18
-10
-2.
+ l
0
- 5
-14
-2.0
-·2.5
* 3a is the frequency of occurrence for inversions in which the base is above the surface (column 3/column 2).
4a, Sa and 6a are standard deviations for the data given in columns 4, 5 and 6, respectively.
19
20 SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
Month
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Table III (Cont 1d). Statistical summary of inversions in which the base is above the surface.
2 3a* 4 4a Sat
Number of A vg height Standard
inversions Frequencyof
Number·of (with base occurrence
soundings above sfc) (o/o)
of base deviation
above sfc
Average Standard
thickness deviation
(m)
300
275
301
287
301
298
306
300
289
305
279
289
260
250
288
287
237
263
254
259
241
267
253
261
296
273
272
298
306
286
305
284
269
276
261
293
139
121
134
167
190
135
62
78
106
166
174
152
82
67
64
90
115
130
113
103
63
79
111
84
107
83
91
130
173
110
96
77
91
126
117
92
46
44
45
58
63
45
20
26
37
54
62
53
32
27
22
31
49
49
44
40
26
30
44
32
36
30
33
44
57
38
31
27
34
46
45
31
{m)
Churchill, Canada ("-l 0-yr record)
450 23 0 590
450
410
450
580
580
440
690
890
810
640
470
240
230
250
330
420
370
470
440
360
370
280
660
560
440
370
340
310
310
320
330
380
540
Clyde River, Canada ("-9-yr record)
630
550
570
660
680
590
490
640
960
940
680
600
320
260
370
320
350
390
350
380
380
340
310
320
520
500
490
450
400
370
320
350
340
320
380
470
Coppermine, Canada ("-l 0-yr record)
610
590
460
510
620
680
680
640
880
840
640
610
310
300
220
300
330
440
420
440
360
340
360
310
690
890
740
580
440
360
370
330
310
380
530
620
380
430
370
290
270
240
180
230
250
240
330
430
400
360
280
310
250
250
220
220
220
240
260
310
430
580
390
410
310
240
210
170
150
260
300
410
6
Avg temp
gradient
("C/100
m)
1.5
1.4
1.3
1.2
1.4
1.2
1.1
1.0
1.1
1.1
1.4
1.6
1.0
1.0
1.1
1.0
1.0
0. 9
1.1
0.8
0.9
1.2
1.0
1.2
1.0
0. 9
1.1
0.9
o. 8
1.2
0.9
o. 8
0.7
0.8
1.0
1.1
6at 7
Standard Avg temp
deviation at base
1.3
1.0
1.0
1.1
1.4
1.0
0. 9
1.0
1.1
1.1
1.2
1.1
o. 7
0.7
o. 8
0.8
o. 7
0.7
1.1
0. 7
0.8
1.2
0.8
1.1
o. 7
o. 5
o. 6
o. 7
0.6
1.2
0.9
0. 8
0.6
0.7
o. 8
0.9
(•c)
-30
-28
-22
-13
-7
-1
+ 7
+ 5
-1
-7
-15
-23
-27
-28
-24
-19
-10
-3
0
-1
-7
-14
-20
-24
-30
-31
-25
-19
-9
-3
+ 4
+ 4
-3
-12
-21
-26
* 3a is the frequency of occurrence for inversions in which the base is above the surface (column 3/column 2).
t 4a, Sa and 6a are standard deviations for the data given in columns 4, 5 and 6, respectively.
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
Month
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Jan
Feb
March
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Table III (Cont'd). Statistical summary of inversions in which the base is above the surface.
2 3 3a*
Number of
inversions Frequency of
Number of (with base occurrence
soundings above sfc) (%)
4
Avg height
of base
above sfc
.0.:2
4a
Standard
deviation
Average
thickness
(m)
Sat
Standard
deviation
Coral Harbour, Canada (~9-yr record)
269
245
271
Z57
277
Z61
265
300
228
291
290
290
Z99
Z69
301
260
303
296
309
305
293
298
293
305
133
137
!52
148
!53
149
!55
179
172
169
170
180
37
32
35
64
159
133
93
99
lOZ
116
57
38
74
44
44
102
241
215
!68
199
203
141
97
73
19
22
14
27
65
71
84
70
28
25
27
12
14
13
13
25
57
51
35
33
45
40
20
13
25
!6
15
39
80
73
54
65
69
47
33
24
14
16
9
!8
42
48
54
39
!6
15
16
7
380 210 510
440
490
510
620
700
620
680
760
720
640
550
230
310
270
330
370
410
420
370
370
370
310
480
420
390
330
330
300
260
270
280
310
420
Mould Bay, Canadq (~1 0-yr record)
310
350
290
340
540
630
600
570
500
450
350
410
250
190
190
290
330
320
310
340
300
320
210
250
620
660
690
540
370
300
300
330
340
340
480
550
Thule, Greenland ("-5-yr record)
800
600
6!0
750
640
390
280
640
760
840
730
760
460
420
450
460
460
430
270
530
450
510
390
400
270
250
300
340
260
320
Z50
300
Z70
zoo
270
32J
430
310
290
280
2!0
230
zoo
160
160
2!0
zoo
290
400
420
370
350
250
zzo
zoo
230
2!0
220
330
350
260
13 0
zoo
310
180
ZJO
140
zoo
160
170
170
280
6
Avg temp
gradient
("C/100
rn2
1,2
1,2
1.3
],I
1.2
1.1
0.8
0, 9
1,0
1.3
1.4
1.3
1.6
1.5
1.5
1.5
1.6
1.3
1.0
1.3
1,1
!.6
!.6
1.6
0. 8
1,4
1.4
0. 7
0, 9
1.2
1.2
0. 9
0.9
1.3
l.Z
0. 6
6at 7
Standard Avg temp
deviation at base
1,0
0,6
1,0
0,8
1,0
o. 8
0.8
o. 7
0.9
0.9
1,0
1.3
!.1
!,4
0.9
1.3
1.6
!.2
0.8
1.3
0.8
],]
1.2
1.0
0,8
1.3
],]
0. 3
0. 9
l.Z
],]
0. 9
0. 9
],]
l.Z
0.4
(•c)
-24
-28
-20
-16
- 8
- 3
+ 5
+ 3
-4
-11
-16
-20
-31
-33
-29
-22
-14
- 4
0
- 2
-8
-18
-26
-28
-zz
-24
-24
-19
- 9
-I
+ 3
0
- 5
-12
-17
-Z4
* 3a is the frequency of occurrence for inversions in which the base is above the surface (column 3/column 2).
4a, Sa, and 6a are standard deviations for the data given in columns 4, 5, and 6, respectively.
21
22 SURVEY OF ARC TIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table III (Cont'd). Statistical summary of inversions in which the base is above the surface.
2 3 3a*
Number of
inversions Frequencyof
Number of (with base occurrence
Month soundings above sfc) (%)
Jan 276
Feb 252
March 277
April 270
May 270
June 269
July 277
Aug 278
Sept 269
Oct 277
Nov 268
Dec 278
15
22
13
28
45
89
84
66
34
25
11
7
5
9
5
10
17
33
30
24
13
9
4
3
4 4at 5 Sat
Avg height Standard Average Standard
of base deviation thickness deviation
above sfc (m)
(m)
Yakutat. Alaska (~9-yr record)
480 360 310
860
1060
860
770
670
780
680
800
790
820
580
410
450
440
500
410
430
450
420
470
400
570
260
370
390
310
340
390
380
390
280
430
190
300
150
230
270
210
220
220
240
350
180
280
80
6
Avgtemp
gradient
(•ct1oo
m)
1. 0
o. 6
1. 0
o. 6
1.0
1.2
o. 9
o. 9
o. 7
0.6
o. 4
o. 6
6at
Standard
deviation
o. 8
o. 6
o. 7
o.s
1.0
0.9
o. 8
o. 6
o. 7
o.s
o. 4
0.5
7
Avgtemp
at base
(•c)
- 7
- 5
- 6
- 2
+ 3
+ 7
+ 8
+10
+ 6
+ 3
- 1
- 2
Table Ilia. Statistical summary of inversions in which the base is above the surface (2400 Z observations).
Jan 277
Feb 253
March 279
April 240
May 248
June 239
July 279
Aug 279
Sept 270
Oct 279
Nov 271
Dec 279
Jan 275
Feb 252
March 276
April
May
June
July
Aug
Sept
Oct
Nov
Dec
270
279
267
310
310
300
310
297
308
42
95
127
57
8
2
4
7
39
121
78
44
39
56
102
113
66
77
122
82
53
92
67
52
15
38
46
24
.J..r
3
14
43
29
16
14
22
37
42
24
29
39
26
18
30
23
17
Fairbanks, Alaska (~9-yr record)
410
540
720
980
1120
1100
1100
1220
880
740
500
370
330
360
370
340
400
330
280
140
390
370
350
280
670
520
390
290
270
110
220
370
290
410
530
650
Nome, Alaska (~9-yr record)
570 290 590
550
470
540
700
510
520
800
1010
950
660
660
310
320
370
450
410
380
390
340
350
280
360
570
530
420
350
390
370
330
330
350
390
390
450
340
350
180
220
20
120
zoo
200
260
400
410
500
370
350
270
220
290
290
230
190
240
270
320
I. 3
1.1
0.9
0.8
o. 5
1.1
o. 8
o. 4
o. 6
o. 8
1.1
1. 3
1.0
o. 9
o. 9
0.8
o. 8
1.4
1. 3
0.9
o. 7
o. 7
I. 0
1. 2
0.9
o. 8
0.8
o. 8
o. 4
0.8
0.8
o. 4
o. 6
0.6
0.8
o. 7
o. 8
0.8
0.9
o. 7
0.7
1.4
1. 3
0.9
o. 7
o. 7
1.0
1.0
-19
-18
-16
-10
0
+ 8
+ 8
+ 5
+ 1
- 7
-15
-23
-15
-14
-15
- 9
- 3
+ 4
+ 6
+ 5
- 1
- 6
-10
-15
>:• 3a is the frequency of occurrence for inversions in which the base is above the surface (column 3/column 2.).
4a, Sa and 6a are standard deviations for the data given in columns 4, 5 and 6, respectively.
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table Illb, Statistical summary of inversions in which the base is above the survace (lZOO Z observations).
Month
z 3 3a*
Number of
inversions Frequency of
Number of (with base occurrence
soundings above sfc) (o/o)
4
Avgheight
of base
above sfc
i!cl
4a1 5 Sat
Standard Average Standard
deviation thickness deviation
(m)
Fairbanks, Alaska (~9-yr record)
Jan Z77
Feb Z54
March 2.79
April Z39
May 2.48
June 2.39
July 2.80
Aug 2.78
Sept 2.69
Oct 2.79
Nov 2.72.
Dec 2.78
Jan 2.75
Feb 2.53
March 2.75
April Z69
May 2.78
June 2.69
July 310
Aug 310
Sept 300
Oct 309
Nov 2.96
Dec 308
38
38
32.
2.8
2.7
19
2.1
15
Z2.
54
55
42.
43
33
34
2.6
2.8
47
79
51
ZB
44
58
45
14
15
11
12.
11
8
8
5
8
19
2.0
15
16
13
12.
10
10
17
2.5
16
9
14
2.0
15
410
440
570
680
660
390
2.80
400
850
740
52.0
370
310
2.80
390
410
440
32.0
2.70
390
460
360
370
2.90
72.0
630
410
450
2.50
2.30
2.40
2.00
2.70
330
550
72.0
Nome, Alaska (~9-yr record)
560
570
560
540
690
570
640
830
1000
92.0
72.0
670
330
330
300
300
300
380
300
370
2.90
400
360
350
540
42.0
330
330
380
390
450
460
310
360
390
460
470
440
2.40
no
190
100
160
110
170
2.10
400
530
470
ZBO
180
2.60
2.60
2.40
zso
2.80
2.40
2.60
Z60
310
6
Avg temp
gradient
("C/100
ml
1,2.
1. 2.
o. 7
0, 6
0.9
o. 8
1. 3
1. 0
o. 7
1,0
1. 2.
1.3
1. z
1.2.
1, 1
0, 8
1. 1
1. 4
o. 9
o. 7
o. 9
0, 7
1.0
1.0
6at 7
Standard Avg temp
deviation at base
0, 8
o. 8
o. 5
0, 5
0, 8
0, 6
o. 8
o. 8
o. 5
1, 0
1. 2.
0, 7
1.2.
1, 2.
0, 7
o. 8
1. 1
1. 2.
o. 7
0,7
0, 8
o. 6
o.s
0, 7
(oc)
-2.1
-2.0
-16
-11
+
+ 9
+10
+ 8
- 1
- 8
-17
·2.1
-13
-14
-14
- 8
- 5
+ 1
+ 4
+ 4
-2.
- 6
-10
-15
* 3a is the frequency of occurrence for inversions in which the base is above the surface (column 3/column 2.),
t 4a, Sa and 6a are standard deviations for the data given in columns 4, 5 and 6, respectively,
Table IV~ Frequency of inversion occurrence, in terms of thickness
and temperature gradient, for two 6-month periods,
Alert, Canada
November through April:
1635 soundings (approximately 10 years of record),
1598 inversions observed (frequency= 97. 7o/o) of which 1357 were with base at the surface, and 2.41
were with base above the surface.
Thickness
i!cl
001-199
Z00-399
400-599
600-799
800-999
~ 1000
.0.1 to <.1,0"
Number of Frequency of
inversions
observed
76
95
88
69
44
12.2.
occurrence
00
4. 6
5.8
5, 4
4.2.
z. 7
7, 5
Temperature gradient ("C/100 m)
1. 0 to< 3. o·
Number of Frequency of
inversions
observed
179
181
110
138
90
137
occurrence
00
10,9
11. 1
6. 7
8,4
5, 5
8. 4
~ 3. o•
Number of Frequency of
inversions
observed
199
55
10
5
0
0
occurrence
00
12.,2.
3,4
o. 6
o. 3
23
24 SURVEY OF ARC TIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table IV (Cont1d). Frequency of inversion occurrence, in terms of thickness
and temperature gradient, for two 6-rnonth periods.
Ale.rt, Cjlnada (Cont 1d)
May through October:
1649 soundings (approximately 10 years of record),
1381 inversions observed (frequency = 83. 7 o/o) of which 743 were with base at the surface, and 638
were with base above the surface.
Thickness
(m)
001-199
200-399
400-599
600-799
800-999
~ 1000
o. 1 to < 1. o•
Number of Frequency of
inversions
observed
155
231
135
92
44
62
occurrence
(%)
9.4
14,0
8. 2
5. 6
2.7
3. 8
November through April:
Temperature gradient (•C/100 m)
1. o to< 3. o•
Number of
inversions
observed
193
174
96
41
22
14
Frequency of
occurrence
(%)
11.7
10,6
5.8
2,5
1.3
o. 8
Barrow, Alaska
1206 soundings (approximately 8 years of record).
::::. 3. o•
Number of Frequency of
inversions
observed
108
12
2
0
0
0
occurrence
(%)
6, 5
o. 7
0, 1
1176 inversions observed (frequency= 97. 5%) of which 557 were with base at the surface, and 619
were with base above the surface.
0,1 to< 1.0•
Number of Frequency of
Thickness inversions occurrence
(m) observed (%)
001-199 36 3,0
200-399 35 2.9
400-599 39 3.2
600-'799 40 3, 3
800-999 61 5, I
~ !000 266 22. I
Max through October:
Temperature gradient (•c /100 m)
J,Oto<3.0•
Number of Frequency of
inversions occurrence
observed (o/o)
66 5, 5
109 9.0
122 I 0, I
103 8.5
61 5.1
98 8,1
1403 soundings (approximately 8 years of record).
::::. 3. o·
Number of Frequency of
inversions occurrence
observed {%)
68 5.6
48 4,0
23 1.9
I 0,1
0
0
1164 inversions observed (frequency= 83,0%) of which 217 were with base at the surface, and 947
were with base above the surface.
001-199 52 3. 7 110 7. 9 77 5, 5
200-399 149 !0, 6 209 14.9 53 3.8
400-599 118 8, 4 133 9. 5 2 0, I
600-799 80 5, 7 48 3.4 0
800-999 66 4,7 4 0.3 0
~ 1000 60 4.3 3 o. 2 0
Churchill, Canada
November through April:
I 731 soundings (approximately I 0 years of record),
1658 inversions observed (frequency= 95, 8%) of which 771 were with base at the surface, and 887
were with base above the surface.
Temperature gradient (•c/!00 m)
0, I to < I, o• 1.0 to< 3,0• ~ 3. o·
Number of Frequency of Number of Frequency of Number of Frequency of
Thickness inversions occurrence inversions occurrence inversions occurrence
(m) observed (%) observed (%) observed (%)
001-199 85 4.9 !52 8,8 109 6,2
200-399 133 7. 7 232 13.4 45 2. 6
400-599 114 6. 6 207 12,0 6 o. 3
600-799 99 5.7 100 5,8 0
800-999 84 4,8 54 3, I 0
~ 1000 192 II, I 46 2.7 0
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table IV (Cont 1d). Frequency of inversion occurrence, in terms of thickness
and temperature gradient, for two 6-rnonth periods.
Churchill, Canada (Cont 1d)
May through October:
1799 soundings (approximately 10 years of record).
1244 inversions observed (frequency= 69.lo/o) of which 507 were with base at the surface, and 737
were with base above the surface.
o. I to < I. o•
Temperature gradient (•c I I 00 m)
I. o to< 3. o• ~ 3. o•
Number of Frequency of
Thickness
!!cl
001-199
200-399
400-599
600-799
·800-999
~ 1000
inversions
observed
152
297
124
53
34
26
November through April:
occurrence
00
B. 5
16.5
6. 9
2.9
1.9
I. 4
Number of Frequency of
inversions occurrence
observed (%)
203 11.3
171 9. 5
66 3. 7
18 1.0
4 o. 2
2 o. 1
Clyde River, Canada
1599 soundings (approximately 9 years of record}.
Number of Frequency of
inversions occurrence
observed (%)
60 3. 3
32 1.8
2 o. 1
0
0
0
1502 inversions observed (frequency= 93. 9o/o) of which 1004 were with base at the surface, and
498 were with base above the surface.
0.1 to< 1.0•
Temperature gradient (•c/100 m)
1. o to< 3. o• ~ 3. o·
Thickness
!!cl
001-199
200-399
400-599
600-799
800-999
~ 1000
Number of
inversions
observed
95
157
127
95
55
H5
May through October:
Frequency of
occurrence
00
5. 9
9. 8
7. 9
5.9
3.4
7. 2
Number of
inversions
observed
176
204
110
78
45
37
1521 soundings (approximately 9 years of record).
Frequency of
occurrence
(%)
II. 0
12.8
6.9
4.9
2.8
2.3
977 inversions observed (frequency 64. 2%) of which 374 were with base
were with base above the surface.
001-199 137 9.0 121 8. 0
200-399 206 13. 5 149 9.8
400-599 159 10.4 39 2.6
600-799 63 4.1 10 o. 7
8Q.0-999 36 2.4 2 o. 1
~ 1000 13 o. 8 0
Co.E.E.errnine, Canada
November through April:
1693 soundings (approximately 10 years of record).
Number of Frequency of
inversions occurrence
observed (%)
166 10.4
33 2. 1
9 o. 6
0
0
0
at the surface, and 603
38 2.5
4 o. 3
a
0
0
0
1575 inversions observed (frequency= 93. Oo/o) of which 955 were with base at the surface, and 620
were with base above the surface.
Temperature gradient (•c /100 m)
o. 1 to < 1. o· 1. o to < 3. o• ~ 3.0·
Number of Frequency of Number of Frequency of Number of Frequency of
Thickness inversions occurrence inversions occurrence inversions occurrence
(m) observed (%) observed (%) observed (%)
001-199 46 2. 7 55 3. 3 17 I. 0
200-399 197 II. 6 167 9.9 7 0.4
40n-599 148 8. 7 107 6. 3 4 o. 2
600-799 108 6. 4 107 6. 3 0
800-999 117 6. 9 81 4.8 0
?. 1000 330 19.5 84 5.0 0
25
26 SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table IV (Cont'd). Frequency of inversion occurrence, in terms of thickness
and temperature gradient, for two 6-month periods,
Coppermine, Canada {Cont 1d)
May through October:
172.6 soundings (approximately 10 years of record}.
·1150 inversions observed (frequency= 66. 6%) of which 477 were with base at the surface, and 673
were witb base above the surface.
Temeerature gradient ("C /100 m)
o. 1 to < 1' o• l,Oto<3,0" -'! 3. o·
Number of Frequency of Number of Frequency of Number of Frequency of
Thickness inversions occurrence inversions occurrence inversions occurrence
_i~ observed ('l'o) observed ('l'o) observed ('l'o)
001-199 125 7. 2 102 5.9 17 I. 0
200-399 310 17.9 160 9.3 24 1.4
400-599 186 10.8 76 4.4 2 0.1
600-799 76 4.4 10 o. 6 2 0.1
800-999 31 I. 8 2 0. I 0
;::_ 1000 26 I, 5 1 0. I 0
Coral Harbour, Canada
November through April:
1622 soundings (approximately 9 years of record).
1583 inversions observed (frequency= 97, 6'l'o) of which 1320 were with base at the surface, and 263
were with base above the surface.
Temperature gradient (•c /100 m)
0. I to< I. o• I. 0 to < 3. O• -'! 3. o•
Number of Frequency of Number of Frequency of Number of Frecpency of
Thickness inversions occurrence inversions occurrence inversions occurrence
(m) observed !'l'ol observed ('l'ol observed (o/o)
001-199 50 3. 1 140 8. 6 196 12..1
200-399 133 8.2 252 15. 5 81 5.0
400-599 91 5.6 177 I O. 9 6 o. 4
600-799 74 4.5 118 7. 3 0
800-999 54 3. 3 58 3. 6 0
-'! 1000 105 6. 5 48 3.0 0
May through October:
1622 soundings approximately 9 years of record).
1158 inversions observed (frequency= 71;4'!o) of which 456 were with base at the surface, and 702.
were with base above the surface.
001-199 162 1 o. 0 225 13. 9 62 3.8
2.00-399 257 15.8 159 9.8 6 • 4
400-599 128 7.9 48 3. 0 0
600-799 53 3.2 11 0.7 0
800:999 27 I. 7 2 • I 0
-'! J()J9 18 Ll 0 0
Fairbanks, Alaska*
November through April:
3188 soundings (approximately 9 years of record).
2862 inversions observed (frequency= 89. 8%) of which 2186 were with base at the surface, and
676 were with base above the surface.
Temperature gradient (•c /I 00 m)
o. 1 to < 1. o• 1.0 to< 3.0• ?. 3. o•
Number of Frequency of Number of Frequency of Number of Frequency of
Thickne11 inversions occurrence inversions occurrence inversions occurrence
(m) observed (%) observed ('l'o) observed (%)
001-199 164 5. I 274 8. 6 335 I 0. 5
200-399 219 6. 9 267 8. 4 227 7. 1
400·599 133 4.2 222 7. 0 82 2.6
600-799 99 3. 1 191 6. 0 8 0. 2
800-999 83 2.6 131 4. l 0 -'! 1000 174 5. 5 253 7. 9 0
*Computations based on 1200 and 2400 Z observations.
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table IV (Cont 1d). Frequency of inversion occurrence, in terms of thickness and temperature
gradient, for two 6-month periods.
Fairbanks, Alaska*(Cont 1d)
May through October:
3187 soundings (approximately 9 years of record).
1510 inversions observed (frequency= 47. 4o/o) of which 1171 were with base at the surface, and
339 were with base above the surface.
Temeerature gradient {"C/100 m)
o. 1 to < 1. o• l. 0 to< 3. o• ~ 3. o•
Number of Frequency of Number of Frequency of Number of Frequency of
Thickness inversions occurrence inversions occurrence inversions occurrence
{!cl_ observed {o/o) observed {o/ol observed {o/ol
001-199 180 5. 6 248 7. 8 125 3.9
200-399 295 9. 2 282 8.8 19 o. 6
400-599 158 5. 0 88 2.8 0
600-799 56 1.8 24 o. 8 0
800-999 17 o. 5 5 o. 2 0
~ 1000 13 o. 4 0 -0
Mould Bay, Canada
November through Aeril:
1727 soundings (approximately I 0 years of record).
1673 inversions observed (frequency = 96. 9o/o) of which 1239 were with base at the surface, and 434
were with base above the surface.
Temeerature gradient ("C/100 m)
o. 1 to< 1. o• 1. 0 to< 3. o· ~ 3. o·
Number of Frequency of Number of Frequency of Number of Frequency of
Thickness inversions occurrence inversions occurrence inversions occurrence
~ observed (o/ol observed (o/ol observed {o/ol
001-199 35 2.0 76 4.4 56 3.2
200-399 63 3. 6 185 10.7 46 2.7
400-599 56 3.2 220 12.8 19 1.1
600-799 60 3.5 207 12.0 4 0.2
800-999 72 4.2 179 10.4 0
~ 1000 222 12.9 173 1 o. 0 0
May through October:
1804 soundings (approximately 10 years of record).
1543 inversions observed (frequency= 85. 5%) of which 376 were with base at the surface, and
1167 were with base above the surface.
001-199 148 8.2 264
200-399 264 14.6 235
400-599 177 9.8 112
600-799 102 5. 7 43
800-999 56 3. I 11
~ 1000 29 1.6 4
Nome, Alaska*
November throu~ril:
3354 soundings (approximately 9 years of record).
14. 6
13.0
6. 2
2.4
o. 6
0.2
79
19
0
0
0
0
4.4
1.1
2384 inversions observed (frequency= 71. 1 o/o) of which 1716 were with base at the surface, and
668 were with base above surface.
o. 1 to < 1. o•
Number of Frequency of
Thickness inversions occurrence
{!cl_ observed (%)"
001-199 223 6. 6
200-399 272 8. I
400-599 169 5.0
600-799 114 3.4
800-999 92 2. 7
> 1000 146 4.4
Temeerature gradient ('C/100 m)
l. 0 to< 3. o•
\lumber of Frequency of
inversions occurrence
observed (o/o)
409 12.2
202 6. 0
114 3.4
56 1.7
42 1.3
49 1.5
~ 3. 0'
Number of Frequency of
inversions
observed
419
63
14
0
0
0
occurrence
.(.f!l
12.5
1.9
o. 4
* Computations based on 1200 and 2400 Z observations.
27
28 SURVEY OF ARC TIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table IV (Cont 1d). Frequency of inversion occurrence, in terms of thickness and temperature
gradient, for two 6-rnonth periods.
Nome, Alaska *(cont'd)
May through October:
3552 soundings (approximately 9 years of record).
1755 inversions observed (frequency = 49. 4%) of which 986 were with base at the surface, and
769 were with base above the surface.
Temperature gradient ("CilOO m)
o. 1 to < 1. o· 1. 0 to< 3. o· ;::: 3. o·
Number of Frequency of Number of Frequency of Number of Frequency of
Thickness inversions occurrence inversions occurrence inversions occurrence
(m) observed (%) observed (%) observed
001-199 231 6. 5 341 9.6 217
200-399 361 10.2 197 5. 5 13
400-599 167 4.7 50 1.4 0
600-799 87 z. 4 13 0.4 0
800-999 52 1.5 0 0
<::. 1000 26 0. 7 0 0
* Computations based on 1200 and 2400 Z observations.
Thule, Greenland
November through April:
920 soundings (approximately 5 years of record).
805 inversions observed {frequency = 87. 5%) of which 684 were with base at the surface, an·d
121 were with base above the surface.
o. 1 to < 1. o•
Temperature gradient (• C I 100 m)
1. o to < 3. o• ;::: 3. o·
(%)
6. 1
0.4
Number of Frequency of Number of Frequency of Number of Frequency of
Thickness inversions
observed
occurrence inversions occurrence inversions occurrence
(m)
001-199
200-399
400-599
600-799
800-999
?. 1000
75
76
28
25
6
17
May through October:
(%)
8. 2
8. 3
3.0
2.7
• 6
1.8
observed
153
102
69
39
19
6
977 soundings (approximately 5 years of record).
(o/o) observed
16.6 171
11. 1 18
7.5 1
4.3 0 z. 1 0
• 6 0
587 inversions observed (frequency = 60. 1 %) of which 244 were with base at the surface, and
343 were with base above the surface.
001-199 103 1 o. 5 126
200-399 133 13.6 59
400-599 63 6. 5 22
600-799 19 z. 0 3
800-999 2 • 2 1
?. 1000 3 • 3 0
Yakutat, Alaska
November through April:
1621 soundings (approximately 9 years of record).
12.9
6.0
2.3
• 3
.1
48
5
0
0
0
0
699 inversions observed {frequency = 43. 1 %) of which 603 were with base at the surface, and
96 were with base above the surface.
Temperature gradient ("C I 100 m)
0.1 to< 1. o· l.Oto<3.0" ;::: 3. o·
(%)
18.6 z.o
.1
4.9
• 5
Number of Frequency of Number of Frequency of Number of Frequency of
Thickness inversions occurrence inversions occurrence inversions occurrence
(m) observed (%) observed (%) observed (%)
001-199 162 10.0 177 10.9 99 6. 1
200-399 132 8. 1 63 3.9 11 0.7
400-599 18 1.1 12 0.7 0
600-799 9 o. 6 5 0. 3 0
800-999 5 0.3 o. 1 0 > 1000 4 o. 2 o. 1 0
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
Table IV (Cont 1d). Frequency of inversion occurrence, in terms of thickness
and temperature gradient. for two 6-month periods.
Yakutat, Alaska (Cont'd)
May through October:
1640 soundings (approximately 9 years of record).
451 inversions observed (frequency~ 27. So/a) of which 108 were with base at the surface, and
343 were with base above the surface.
Thickness
~
001-199
200-399
400-599
600-799
800-999
~ 1000
0. 1 to< 1. 0'
Number of
inversions
observed
67
121
52
37
10
7
Frequency of
occurrence
_{%)
4. 1
7.4
3.2
2.2
o. 6
0.4
Temperature gradient, ('C I l 00 m)
I. 0 to< 3. 0' 2 3. o•
Number of Frequency of Number of Frequency of
inversions occurrence inversions occurrence
observed (o/o) observed (%)
84 5. l 12 0.7
47 2.9 1 o. 1
9 o. 5 1 o. l
3 0.2 0
0 -0
0 -0
29
31
APPENDIX A. TYPICAL ARC TIC TEMPERATURE INVERSIONS
MOU~ r-J'\.
BAY v--' ~~ALERT
\)(:7 cG;/
~ CENTURY
j oSITE II
GREENLAND
0
EISMITTE
Figure Al. Location map.
Information on temperature inversions
on ice sheets is limited because few radio-
sonde observations have been made in these
areas. A thorough search for immediately
available material provided short records
for three stations on the Greenland ice sheet
(Eismitte, Site 2, and Camp Century) and
for three other widely separated Arctic sta-
tions ( Camp Tuto #1, Alert, and Mould
Bay). The locations of these six stations are
shown in Figure Al.
The most useful information was ob-
tained from Georgi (1957). This information
is unique because it provided temperature
soundings on an ice sheet during the winter
period. Figure A2 is a reproduction of the
temperature profiles taken during the
Deutschen Gronland Expedition A. Wegener
1930-31 and Expeditions Polaires Francaises
1949-50 to interior Greenland. The Ger-
man text* which accompanied the figure
was translated by Dr. Fritz Kasten, Envi-
ronmental Research Branch, as follows:
"The main reason for the soundings was
to investigate the temperatur.e inversion;
this inversion is formed at a few hundred
meters above the ice cap, when in calm
"radiation weather" ( 1Ausstrahlungswetter') the firn surface cools down well be-
low the temperature of the air above the ice cap. Due to the lasting contact, the
air layer immediately above the firn cools down as much as the firn itself; the air
layers above also cool down due to contact with the colder layers underneath. But
one realizes at once that this cooling decreases with increasing height due to the
low heat conductivity of the air, until, by sudden transition, the original air tem-
perature is reached again.
"That there is not necessarily a temperature inversion above the surface of
the ice cap -although inversions are very frequent -is demonstrated by the two
dashed soundings. High wind velocity, particularly, causes strong vertical mixing
of the lowest layers even in winter whereby a potential inversion is destroyed. In
summer, the firn surface and the incumbent air layer can be warmed up by strong
solar irradiation so that the temperature decreases steadily with height; this is
represented in the two soundings of 19 January 1950 and 2 September 1930."
Upper air observations during two summer periods were conducted at Site 2,
and a brief record (32 days) during the summer-winter transition period was avail-
able for Camp Century, Greenland. t The average temperature profiles and the
maximum inversions observed are shown in Figures A3 and A4.
*Georgi, J. (1957) 1m eis vergraben, Leipzig: Brockhaus Verlag (text in German).
tDepartment of Commerce (U.S. Weather Bureau). Summary of Constant Pressure
Data, Form WBAN -33. Site II, (Camp Fist Clench), Greenland, May-August
~May-August 1960. Camp Century, Greenland, September-October 1960.
32 APPENDIX A
The significant points derived from these diagrams are: 1) inversions on the
Greenland ice sheet become steeper toward winter and, 2) they appear to be con-
fined to within 400 to 500 m above the snow surface. The average increase in
temperature over that height varies from negligible amounts in summer to about rc in early winter. Numerical coded soundings from the French expedition at
Station Centrale in Greenland indicate the average winter inversion is about 300m
deep with an increase in temperature of 8°C. * Isothermal conditions and instances
of decreasing temperatures, however, are common during the summer and can
occur at any time of the year.
Soundings were available for Camp Tuto at the edge of the Greenland ice sheett
and two locations at sea level in the Canadian Arctic Archipelago, Alert and Mould
Bay.>:<* A plot of the record (only summer months available) for Camp Tuto #1
(Fig. A5) indicates that few inversions can be expected here during this time of
the year. The soundings at Alert and Mould Bay could be definitely classified into
two seasons: the "light" or summer period and the "dark'' or winter period. The
temperature profiles from May to near the end of October were isothermal for
most of the time or the temperature decreased with height, whereas between Novem-
ber and April the bulk of the soundings showed inversions. The average temperature
profiles for these two periods and the maximum inversions observed are shown in
Figures A6 and A 7.
It is noted that the inversions apparently extend higher (1200 to l500m) at
stations of lower elevation than on the ice sheet. Also, the average increase in
temperature for the winter inversions at the sea level stations approximates 7° C.
Acknowledgements: This research note was prepared with assistance from Dr.
Fritz Kasten and Mr. Roy Bates.
>:<Victor, P.E. (1950) Recueil des Observations Meteorologiques, effectuees par la
Station Francaise du Groenland entre le 20 Juillet 1949 et le 14 Juillet 1950,
Expeditions Polaires Francaises.
tDepartment of Commerce (U.S. Weather Bureau). Summary of Constant Pressure
Data, Form WBAN -33. Cam_? Tuto (Station I), Greenland, May-September 1958.
*':<Department of Transport (Canada), Arctic Summary, Semi-annual Summary of
Meteorolo ical Data from Weather Stations on the Canadian Arctic Islands. De-
partment of Transport, Meteorological Branch, January 19 0-June 1961.
6000 3000
w u
<(
2000 ~
::;)
VJ
3:
0
1500~
( w I
I >
2 SEP\
0
1930 \ 1000~
E I .....
I J:
_j I (!)
w I w > I
w I J:
.J I
I
<( I
w I
Ul I
w ~INVERSION OF 29.4 °C~ > 0
Ill IN 350m. SNOW SURFACE
<( EISMITTE, GREENLAND
.....
J:
<!) w
J:
OL-~~--~_L~L_.J_~ __ L_-L_.J __ ~-L--L-~
-so -5o -4o -30 -2o -10 o 10
TEMPERATURE, °C
6000
E
_j
w > w
.J
<( w
Cf) 3000 -
w >
0
Ill
<( 2500 .....
J:
(!)
w
J: ----
I 500 [_
I
I
I
I
I
I \
I
I
I
\
AVERAGE 1
PROFILE" I
I
I
I
\
\
I
I
I
I
\
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
SNOW SURFACE
SITE 2, GREENLAND
If Period of Recora: 28 May to 2 August 1959 and
20 May to 21 Aur;usl 1960
-1 3000
2500 E
w u
<(
LL
2000 !3
VJ
3: 0
1500 iii
w > 0
Ill
I 000 <l .....
J:
<!) w
J:
Q'-----'--..__---'-_J__~--'-------'-_L_--'---'--'----'--.L._----'
-60 -50 -40 -30 -20 -10 0 10
TEMPERATURE, °C
Figure A2. Temperature profiles, Eismitte, Green-Figure A3. Temperature profiles, Site 2, Greenlansf,
land 1930-31 and 1949-50.
> 1:)
1:)
M z
tj
H
:><:
>
I.N
I.N
6000.
\ 6000 ~ I I I I I J ~
\ 5500 1 500C
\ \
I 3000 \ I I I
I \ I .
AVERAGE\ 5000 \ --,4500
PROFILE*\ I
\ 2500 E \
I • \
\ t_j 4500 I -l4000
I ~ \
\ ll.. \
1 2000 ~ \AVERAGE
I (/) 1 PROFILE• E
~ 3500 \ <500 ! ~ :::: ~" \ :::: :
...J I 0 W (f)
I ID -' 3: ~ \ I 000 ~ ~ 0
1-1-1-z
l: :I: J: tl ~ 0 ~ ~ H
:r: 2ooo ~ 2000 L 16oo ~ ::><
SNOW SURFACE I >
CAMP CENTURY, GREENLAND ~
I 500 t-I I 500 r ·~ \ --j I 000
I 000 ~ 1000 L i I _, 500
! SURFACE, 490 m ~ CAMP TUTCl I. GREENLAND
Mpsriotl of Record: 9 Sepfsmbsr to II Ocfob" 1960 L _L
5oo -5oo ---" -lo
*Period of Record: 15 May lo 12 September !9'8
0 O'-----'---'------'---'---..._____.__~
-60 -50 -40 -30 -20 -10 0 10 -60 -50 -40 -30 -20 -10 0 10
TEMPERATURE, °C TEMPERATURE,"c
Figure A4. Temperature profiles, Camp Century, Figure A5. Temperature profiles, Camp Tuto # 1.
Greenland.
6ooor-~-,--~~--.--r-.--.--.--.--.-.--.-~
5500
5000
4500
4000
E
...J
~ 3500 w
...J
<t w
C/) 3000
w >
0
CD
<t 2500
1-:r
':2 w
:r 2000
1500
1000
500
c
-60
"oar It" or Winter Period: I./on to 30 Apr 1960 and
I Nov 1960 to 30 Apr 1961
"Ligflt" or Summer Penod: I May to 31 Oct /960
-50
I
I
I
I
I
I
I
I
I
I
I
I
I
AVERAGE I
~RO~,ILE \
I
I
I
I
I
I
I
I
I
I
I
Dark or \
Winter Period \
I
I
I
I
I
\
I
I
I
I
I
I
I
I
I
I
\ AVERAGE
I PROFILE
\ "uoht" or
,summer Period
I
I
I
I
\
I
I
I
I
MAXIMUM \---
INVERSION---------r-
I
I
I
I
I
2 JAN 1960 I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
\
-40 -3P -20 -10
TEMPERATURE, °C
0 10
Figure A6. Temperature profiles, Alert, N. W. T.,
Canada.
6000
'Dark" or W1nfer Period: I Jan to 30 Apr /960 and
II Jon fo30 Apr 1961
5500 /-'Lqnt"or Summer Period: I May to 31 Oct /960
I
I
I
I
5000 f--\'. I
I
I
I
I
I
4500 f--' I
I
I
I
I I
I 4000 I I I E I I
.] I I
I I w AVERAGE I \ AVERAGE ~ 3500 PROFILE I I PROFILE
...J "Dark" or I \ "Light" or
Winter Period I \ Summer Period
<t I I w I \ :3000 \ I
> I I
0 I \ CD I I <t I I
I-2500 I I :r I I ':2 I I
w MAXIMUM~ I :r I
2000 INVERSION \ I
16 FEB 1960 1 I
I I
I I
1500 r-I I
I I
I I
I I
I I
I 000 f--I I
J I
I I I SURFACE, 15m I I 500 f--MOULD E!AY, N.W.T. CANADA I. I
0 -60 -50
Figure A7.
I I
I
I
I
-40 -30 -20 -10 0 10
TEMERATURE,°C
Temperature profiles, Mould Bay,
N. W. T., Canada.
> 1::)
1::)
M z
~
:><
>
I..V
\J'1
Unclassified
Security Classification
DOCUMENT CONTROL DATA · R&D
(Security claeeillcation ol title, body of abstract and indexing .-,notation must be entered when the overall report is classilied)
1. ORIGINATING ACTIVITY (Corporate author) 2a. RI!POAT SECURITY CLASSIFICATION
Unclassified
u.s. Army Cold Regions Research and 2b GROUP
Engineering Laborator_y. Hanover N.H.
3. REPORT TITLE
SURVEY OF ARCTIC AND SUBARCTIC TEMPERATURE INVERSIONS
4. DESCRIPTIVE NOTES (Type ol report and inclusive dates)
Technical Report
s. AUTHOR(SJ (Lll8t nllme. first name, Initial)
Bilello, Michael A.
6. REPORT OA TE 7a. TOTAL NO. OF PAGES: 17b. NO. OF 8EFS
Oct 1966 38
Sa. CONTRACT OR GRANT NO. 9a. ORIGINATOR'S REPORT NUMBER(SJ
b. PROJECT NO. Technical Report 161
I cDA Task IV014501B52A02 9 b. OTHER REPOR:T NO(S) (Any other numbers that may be assillned I
this report)
d.
1 O. AVAIL ABILITY /LIMITATION NOTICES
Distribution of this document is unlimited.
11. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY
U.S. Army Cold Regions Research and
Engineering Laboratory
13. ABSTRACT
This study provides a statistical analysis of available data on Arctic and
subarctic inversions, and includes data from locations in Canada, Greenland,
and Alaska. The analysis considers inversions with respect to frequency, base
height, thickness, base temperature, and temperature gradient.
-
DO FORM
1 .JAN 84 1473 Unclassified
Security Classification
Unclassified
Security Classification
14. LINK A LINK 8 LINK C
KEY WORDS
ROLE WT ROLE WT ROLE WT
~-----------------------------------------------------+------+-----~-
Air temperature -Alaska
Air temperature -Canada
Air temperature -Greenland
Air temperature -Statistical analysis
Atmospheric circulation -Arctic regions
Atmosphere_-Thermodynamic properties
INSTRUCTIONS
1. ORIGINATING ACTIVITY: Enter the name and address
of the contractor, subcontractor, grantee, Department of De-
fense activity or other organization (corporate author) issuing
the report.
2a. REPORT SECURITY CLASSIFICATION: Enter the over-
all security classification of the report. Indicate whether
"Restricted Data" is inc! uded. Marking is to be in accord-
ance with appropriate security regulations.
2b. GROUP: Automatic downgrading is specified in DoD Di-
rective 5200.10 and Armed Forces Industrial Manual. Enter
the group number. Also, when applicable, show that optional
markings have been used for Group 3 and Group 4 ·as author-
ized.
3. REPORT TITLE: Enter the complete report title in all
capital letters. Titles in all cases should be unclassified.
U a meaningful title cannot be selected without classifica-
tion, show title classification in all capitals in parenthesis
immediately following the title.
4. DESCRIPTIVE NOTES: If appropriate, enter the type of
report, e. g., interim, progress, summary, annual, or final.
Give the inclusive dates when a specific reporting period is
covered.
5. A\]THOR(S): Enter .the name(s) of author(s) as shown on
or in the report. Enter last name, first name, middle initial.
If military,• show rank and branch of service. The name of
the principal author is an ,absolute minimum requirement.
6. REPORT DATE: Enter the date of the report as day,
month, year; or month, year. If more than one date appears
on the report, use date of publication.
7a. TOTAL NUMBER OF PAGES: The total page count
should follow normal pagination procedures, i.e., enter the
number of pages containing information.
7b. NUMBER OF REFERENCES: Enter the total number of
references cited in the report.
8a. CONTRACT OR GRANT NUMBER: If appropriate, enter
the applicable number of the contract or grant under which
the report was written.
8b, 8c, & 8d. PROJECT NUMBER: Enter the appropriate
military department identification, such as project number,
subproject number, system numbers, task number, etc.
9a. ORIGINATOR'S REPORT NUMBER(S): Enter the offi-
cial report number by which the document will be identified
and controlled by the originating activity. This number must
be unique to this report.
9b. OTHER REPORT NUMBER(S): If the report has been
assigned any other report numbers (either by the originator
or by the sponsor), also enter this number(s).
10. AVAlLABILITY /LIMITATION NOTICES: Enter any lim-
itations on further dissemination of the report, other than those
imposed by security classification, using standard statements
such as:
(1) "Qualified requesters may obtain copies of this
report from DDC ''
(2) "Foreign announcement and dissemination of this
report by DDC is not authorized."
(3) "U. S. Government agencies may obtain copies of
this report direct! y from DDC. Other qualified DDC
users shall request through
(4) "U. S. military agencies may obtain copies of this
report directly from DDC Other qualified users
shall request through
(5) "All distribution of this report is controlled. Qual-
ified DDC users shall request through
If the report has been furnished to the Office of Technical
Services, Department of Commerce, for sale to the public, indi-
cate this fact and enter the price, if known.
11. SUPPLEMENTARY NOTES: Use for additional explana-
tory notes.
12. SPONSORING MILITARY ACTIVITY: Enter the name of
the departmental project office or laboratory sponsoring (pay-
ing for) the research and development. Include address.
13. ABSTRACT: Enter an abstract giving a brief and factual
summary of the document indicative of the report, even though
it may also appear elsewhere in the body of the technical re-
port. If additiona·l space is required, a continuation sheet
shall be attached.
It is highly desirable that the abstract of classified re-
ports be unclassified. Each paragraph of the abstract shall
end with an indication of the military security classification
of the information in the paragraph, represented as (TS), (S),
(C), or (U).
There is no limitation on the length of the abstract. How-
ever, the suggested length is from 150 to 225 words.
14. KEY WORDS: Key words are technically meaningful terms
or short phrases that characterize a report and may be used as
index entries for cataloging the report. Key words must be
selected so that no security classification is required. lden-
fiers, such as equipment model designation, trade name, '11ili-
tary project code name, geographic location, may be used as
key words but will be followed by an indication of technical
context. The assignment of links, rules, and weights is
optional.
Unclassified
Security Classification