948 
Bay station in 1948, shows the vertical structure of 
continental arctic air as it flows southward from the 
Canadian Archipelago in the Baffin Bay cyclonic cir- 
culation. The arctic air arrives at Resolute Bay after 
passing over frozen waterways en route from a colder 
source region, exhibiting characteristic surface tur- 
bulence and instability. Specific humidity values are 
near the annual minimums of 0.2 to 0.3 g kg with 
little variability throughout the deep and surface-con- 
trolled thermal equilibrium below the 700-mb level. 
The average height of the tropopause is about 8300 m 
(27,500 ft) in winter. 
January 1948 had a number of striking departures 
from the normal circulation patterns. The existence of 
an arctic “high’’ has been mentioned, and that—in 
conjunction with an active arctic frontal zone across 
northern Canada—created an unusually strong flow 
across southern sections of the Archipelago. Thus, the 
January average sounding probably shows more warmth 
and moisture than would be observed in a long-term 
average. 
April. Despite the 24-hr insolation in spring over 
the region investigated, there is little immediate change 
in the surfaces underlying arctic air masses, and April 
retains much of winter’s coldness. The average sound- 
ing, from 26 ascents to the 250-mb level above Resolute 
Bay in April 1948, is still typical for continental arctic 
air but shows a distinct moderation from the severe 
winter characteristics of the regional air mass. The 
winter temperature contrast between ice fields and land 
has been eliminated, allowing an increase in surface 
stability, but the Baffin Bay cyclonic circulation ex- 
tends back over Resolute Bay above the 800-mb level. 
Apparently the tropopause height varies between the 
7500- and 8500-m levels in April. 
The American Arctic Versus the Eurasian Arctic. 
A brief survey of the Eurasian arctic data has pro- 
vided a few ‘‘typical” soundings which are included in 
Fig. 8 to illustrate characteristic regional variations in 
WINTER SUMMER 
-60° -50° -40°C Sle? S5pP SAP see orc 
14 re 14 
R | E-EUREKA SOUND 
a i i F-FRIDTJOF NANSEN 
12 t LAND 
' | i M-"MAUD" IN PACK ICE 
6 ! R-RESOLUTE BAY 
FA: j S-SPITSBERGEN 
me 1 Z-NOVAYA ZEMLYA we 
uy Zz i :, | i | wy 
t 8 = 5 = 
Ww \ Ww 
= N = 
S} S S 
= oN = = 
L045, & 
4 Liles 
2 
(0) 
7 Os OO no OnE 4 Osmn SOME 2 OD Soy {Ko} o° 1o°c 
Fic. 8—Comparative soundings. 
arctic air. Because of its high latitude and great distance 
from the major frontal zones, northern arctic America 
produces a distinctive continental type of arctic air. 
With reference again to Fig. 8 for summertime com- 
parisons, it will be seen that the surface temperatures 
POLAR METEOROLOGY 
are lowest over the pack ice and highest over the rela- 
tively large ice-free land areas of northern arctic 
America. The coldness and low-level instability of the 
Maud sounding result from the incorporation of June 
and August data in the summer “average,” and from 
the fact that steady winds and stirred air were neces- 
sarily present during successful kite flights. The Fridtjof 
Nansen Land sounding shows relatively warm maritime 
polar air, cooled in its lower levels over the arctic ice 
fields, and brought onshore in a strong return flow over 
cold water. Maritime arctic air reaches Spitsbergen 
in a steady flow across relatively warm water. Land 
heating of the coldest type of maritime arctic air pro- 
duces convective instability over arctic America, but 
near icy waterways the lowest levels are stabilized by 
the sea-breeze circulation. The tropopause heights show 
maritime influences over Fridtjof Nansen Land, but 
Eureka and Spitsbergen have the typical, uncompli- 
cated arctic tropopause, with Kureka’s lower because of 
greater insolation aloft and proximity to a “normal” 
upper-level vortex. 
In winter the Arctic Archipelago is colder than the 
pack ice, but the Baffin Bay circulation prevents the 
formation of extreme temperature inversions of the 
pack ice or continental interior type. The Fridtjof 
Nansen Land sounding shows maritime polar air after 
a relatively short period of cooling from below, with 
a maritime polar tropopause being frequently observed. 
Many of the “winter” soundings at Novaya Zemlya 
were made in the rear quadrants of intense storms. They 
show evidence of strong stirring in continental arctic 
air and a complex tropopause mixture of low arctic and 
extremely cold maritime types. The Resolute Bay 
sounding shows the comparatively stable continental 
arctic air extending all the way to a warm arctic tropo- 
pause. 
In addition to the temperature-versus-height curves 
compared in Fig. 8, the annual range of average mois- 
ture and stability conditions in Eurasian and American 
arctic air masses is shown by means of a brief tabular 
comparison (Tables I and II). The Eurasian data for 
Tape I, Arctic Arr IN WINTER 
F H T Osw 
Seiden (ab) | Gm) | Cc) exe} CO 
Resolute Bay 1000 75 | —31 | 0.16 | —32 
(all soundings) 900 | 800 | —26 |} 0.32 | —19 
800 | 1650 | —26 | 0.30 | —13 
700 | 2600 | —30 | 0.25 | — 9 
600 | 3700 | —35 | 0.22 | — 4 
500 | 4950 | —43 | 0.06 | — 2 
Fridtjof Nansen Land 1000 | — = = = 
(stirred air) 900 | 750 | —30 | 0.29 | —24 
800 | 1550 | —34 | 0.21 | —20 
700 | 2450 | —38 | 0.16 | —15 
600 | 3500 | —42 | 0.12 | —10 
500 | 4650 | —49 | 0.07 | — 6 
arctic air in winter and summer were obtained from 
Petterssen [14]. The physical properties chosen for com- 
parative purposes, specific humidity (q) and potential 
psuedo-wet-bulb temperature (6,.), are conservative 
