920 
The cold surface of the Antarctic continent is continually 
removing air from the general circulation. This lies over it 
as a cold layer of varying thickness which flows outward to 
the periphery under the influence of gravity, giving the well- 
known katabatie winds.... The cold air accumulates es- 
pecially along the coast of the continent where it appears 
to raise the air pressure by about 0.2 inch above what is 
observed over the open sea, far from the shore, in corre- 
sponding latitudes (for example, over the Ross Sea). It is 
responsible for a prevalence of easterly winds along the ant- 
arctic coastline and its effect extends, on the average, for 
about 200 miles from the coast. Pressure systems, fronts, 
waves, cyclones, ete., move to a large extent, over and in- 
dependently of the cold layer. Fluctuations in the katabatic 
flow are, of course, produced. 
Seasons. These various models of Antarctica’s circu- 
lation make no great distinction between summer and 
winter, yet all seem in general to be based on winter 
conditions. Memardus [14] did suggest that the north- 
south pressure gradient above 2 km is especially strong 
in winter. As will be explained later, it is likely that 
both the temperature and pressure gradients aloft re- 
verse from summer to winter, and it is gross oversimpli- 
fication to say, as did Haurwitz and Austin [133], 
“Hyven though the south polar sea-level anticyclone is 
very pronounced, the strong north-south temperature 
gradient probably results in a polar cyclone at low 
altitudes.” 
By contrast, most of the comments of recent years 
imply some seasonal variation in Antarctica’s circula- 
tion. Thus Serra and Ratisbonna [42] considered that 
“The cold antarctic anticyclone [is] greatly weakened 
in summer and forced back toward the pole,” and that 
the upper cyclone is found above 2 km in summer, and 
above 3 km in winter. Coyle [27], like them primarily 
interested in antarctic influences on South American 
weather, reasoned similarly. Gentilli [9] recently as- 
sumed that ‘the area of prevailing polar easterlies 
contracts in summer and expands in winter.” 
Meteorologists of the U. 8. Navy’s Operation High- 
jump* during the summer of 1946-47 suggested [2] 
that “The south polar anticyclone is broken up into a 
number of cells with their centers displaced to the 
northward.”” Two such cells, representing persistent 
outflows of cold air, were found around 120°W and 
145°H, plus a narrow wedge along the Palmer Penin- 
Sula (65°W), a semipermanent wedge along 80°H, and 
& migratory or transitory wedge between the Mac- 
Kenzie and Weddell Seas (20°W to 70°E). The 145°E 
position was given by the Ross Sea group; the western 
group placed this “Balleny Island wedge” along 155°H. 
No such cells had been shown by Meinardus [14] on 
his map of mean annual pressures, but Lamb’s revision 
3. While the full aerological reports of Operation Highjump 
[2] and Task Force 39 [4] are classified as ‘“‘Restricted’’ by the 
Navy Department, the actual observations [3] are unclassified, 
and the discussions and conclusions in the Restricted reports 
are considered unclassified, so that one unclassified summary 
[1] of conclusions has appeared. The generous co-operation of 
Capt. H. T. Orville, Chief of Aerology, permitted access to the 
full reports and obtained official clearance for their use and 
quotation here. i 
POLAR METEOROLOGY 
[83] suggested three areas with pressures greater than 
995 mb centered on 80°S, at 20°H, 130°H, and 90°W. 
Earlier Lamb concluded [81] that ‘we should think of 
the south polar anticyclone not as a permanency but 
as a recurrent feature subject to most of the same laws 
of life and decay that apply to high pressure systems’ 
everywhere.” 
Upper winds at Little America during two full years 
[50] show the circulation to be far more complex than 
would result from a permanent surface anticyclone 
with upper cyclone, or any other simple model. Grim- 
minger, who tabulated and summarized the data, said 
[49]: 
The annual means show very clearly winds with south and 
east components at the low levels and with north and west 
components at the higher levels and agree qualitatively with 
the concept of the outward drainage of cold air below and a 
compensating inflow aloft.... The south components are 
distinctly larger in winter than in summer up to 1,000 m; this 
is even more pronounced during the coldest period and extends 
to 2,000 m. In the upper layers. ..there are larger north 
components in winter than in summer at 7 and 8 km and in 
the coldest period from 5 to 9 km. 
In general, the seasonal variation of the north-south com- 
ponents agrees with what would be expected if the circulation 
over the continent were controlled mainly by the drainage 
of the cold lower layers. The seasonal variation of the east- 
west components in the upper layers also agrees with this; 
but that of the lower layers does not, since as pointed out 
above the east components are smaller in winter and are 
lacking entirely during the 3 coldest months.... Just why 
these east components do not appear in the coldest months 
when the drainage should be a maximum is not clear. 
From the same data, Palmer [62] found deep easterly 
winds, 2.e., continuously between north-northeast and 
south-southeast up to 5 km, on 38 per cent of all days 
with flights to 5 km or higher, and on 44 per cent of 
days with flights to 3 km or higher. These easterlies 
aloft ‘‘are far more frequent than would be expected 
from the theory of the polar vortex.” 
It is obvious from its derivation that the idea of a “polar 
vortex” is an abstraction, adequate, perhaps, as a summary 
of average conditions, but misleading if applied to the analysis 
of individual synoptic situations in the far south. To find, 
by the manipulation of mean values, that the antarctic anti- 
cyclone is on the average a shallow pressure feature may be 
justified, but to deduce from this that all easterly, south- 
easterly and southerly winds, and in particular the blizzards, 
are “‘katabatic” or are shallow surface flows is to obtain a 
result that is really beyond the capacity of climatological 
methods. 
Similarly, Meinardus pointed out repeatedly that 
mean annual pressure maps are merely averages of daily 
weather patterns, and [14] that “the direction and 
force of the air motion on the inland ice are governed 
not only by the direction of the slope but also by the 
general pressure distribution,” which changes from day 
to day. 
The 426 pilot balloon and rawin ascents made on 
Highjump [2], operating at sea all around the conti- 
nental margin, were summarized for three levels: “2,000 
