CLIMATOLOGICAL PROBLEMS IN THE ARCTIC AND SUB-ARCTIC 
Russian sources and is hence inaccessible. The review 
that follows is as inadequate as the subject is important. 
All that can be attempted is a review of the fields in 
which research is at present active. 
The physics of sea-ice formation, of its drift, and of 
the deformation induced in it by atmospheric dis- 
turbance lies beyond the scope of this article. A general 
summary of present knowledge was recently prepared 
by Gordon and Woodsworth [16], and a review of 
Russian work in the field has been published by Zubov 
[69]. In North America most research in this field is 
contained in various publications of the U. 8. Hydro- 
graphic Office [60]. 
Much time has been spent by research climatologists 
on the influence of arctic sea ice on the climate of the 
middle latitudes. Particular attention has been paid 
to the Labrador and East Greenland Currents, which 
are the chief routes by which heavy arctic pack enters 
lower latitudes [21]. This is a question of vital impor- 
tanee in the study of climatic change, but has less 
direct reference to the arctic climates themselves. In 
Greenland and along the Labrador Sea, however, the 
relationship is direct, and will be discussed later. 
Hudson Bay: A Concrete Example. Until 1945, it . 
was generally assumed that Hudson Bay remained un- 
frozen throughout the winter, despite the grim cold 
of nearby land areas. This assumption had the sup- 
port of Canadian, British, and American official papers. 
Many authorities entered into considerable detail in 
describing the narrow belt of fast ice along the shores, 
but insisted that the central area rarely or never froze 
from shore to shore. The coastal fast ice was variously 
stated as being 5 to 60 mi wide [59]. 
This early view was first challenged when military 
aircraft began flying across the northwestern flanks of 
the Bay during World War II [49]. In March 1948, 
Lamont [37] flew directly across the central area of the 
Bay, photographing an unbroken pack covering the 
whole area. Since then regular reconnaissance flights 
have been made across all parts of the Bay by the 
Royal Canadian Air Force, with scientific observers 
on all flights and with complete photographic records. 
These flights have established that the Bay freezes 
annually in the late fall and is completely frozen from 
January until June, except for (1) a coastal lead, 
separating fast ice from the central pack, and (2) small, 
temporary leads or fissures set up in the central parts 
by storms, tides, and other sources of stress. These 
new facts have been summarised by Montgomery [20, 
Part II]. Associated with the reconnaissance program, 
there has been some active research, to be described 
below. 
Burbidge [3] set out to examine the changes wrought 
in continental polar air masses in their travel across 
the Bay. By plotting trajectories at the main aerological 
levels, he was able to trace changes in the air before it 
arrived at the east coast aerological station of Port 
Harrison (58°27’N, 78°08’W). His results can be sum- 
marised as follows: 
1. In the fall, before the freeze-up, great heating 
and dampening occur in the airstreams as they cross 
959 
the warm open water. This effect rises to a maximum 
in late November and early December, when the sur- 
face temperature rises an average of over 20F (11C) 
in the crossing from west to east. Thereafter, the con- 
solidation of sea ice cuts off the source of heat, and 
heating is negligible from mid-January on; apparently 
the snow-covered ice surface entirely insulates the water 
below. Curve (f) in Fig. 2 shows the amount of this 
JASONDJIFMAMY SO Nb) J F hm A 
(e) (7) 
: IN. 
4 4 
(hy YEMAMJJ ASOND 
Fic. 2—A summary of the evidence bearing on the freeze-up 
of Hudson Bay. Maps (a-d)—mean air temperature, 1930-48, 
November-February. Curve (e)—temperature differences 
(upper curve) between west and east coast of Baffin Bay at 
latitude 70°N, showing year-round mildness of Greenland 
coast; (lower curve) between west and east coast of Hudson 
Bay, showing greater warmth of east coast during fall months 
only. Curve (f)—Burbidge’s modification curve for cP air- 
streams (see text). Curves (g) and (h)—mean monthly pre- 
cipitation for Port Harrison (g) and Great Whale River (h) 
on east coast of Hudson Bay. 
warming effect month by month. The rapid decline 
after December is very striking. 
2. This heating leads to the development of an un- 
stable layer at low levels, with lapse rates close to the 
dry adiabatic. By late November, the peak time, the 
average depth of the unstable layer is 7000 ft, and may 
attain 10,000 ft. Dense cumuliform cloud and frequent 
snow flurries occur within the layer, and total snowfalls 
along the Quebec coast are heavy (over 30 in. in No- 
vember). With the freeze-up, the unstable layer dis- 
appears or becomes very shallow (less than 1000 ft) 
as do the cloud and snow. In Fig. 2, diagrams (g) and 
(h) represent mean monthly precipitation at Port Har- 
rison and Great Whale River, respectively, on the east 
coast of the Bay. In both cases heavy autumnal snow 
gives way to light falls in the new year. 
