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Immediate report on the Victoria University of Wellington Antarctic Expedition 1959-60: VUWAE 3
E. METEOROLOGY
E. METEOROLOGY
Continuous recordings of temperature, relative humidity and barometric pressure were made at main base from November 30 to January 31. A continuous-run anemometer was also operating. Standard observations of temperature (ambient, maximum and minimum); wind direction and velocity; cloud cover, height and direction of movement; and weather phenomena were made at 1200 and 1800 hours. Wind, cloud and weather observations only were made at 0900 end 2100 hours. A secondary station, recording temperatures and relative humidities, also operated at Lake Vida, 15 miles to the east, for four weeks.
During the previous V.U.W. expedition into the Wright Valley to the south, Bull found that in the western end of the valley the wind blew from the west, with low humidity and relatively high temperatures, or from the east, with high humidity and relatively low temperatures; while at the eastern end there was invariably an easterly wind. The purpose of establishing two stations this year, on towards the west and the other to the east, was to obtain more data on this wind structure.
The data has not yet been fully analysed, but the following results are to hand:
Temperature
The average temperature for December was 32.2°F. and for January 27.8°F. The maximum temperature was 54.2°F and the minimum 9.6°F, both occurring in December.
Judging from ice-conditions on the lakes and streams, and from the experiences of the two previous expeditions into the area, the temperatures recorded this summer were considerably colder than in a normal year. This was also the case at Scott Base and other points in McMurdo Sound.
The temperature did not rise above freezing point for two days in December and eleven days in January. The longest cold spell was from January 18 to 23 when the temperature remained constantly below freezing point.
Slight thawing occurred at Lake Vashka on three occaions in December following three two-days periods when the temperatures rose above 40°F. Apart from these occasions the lake remained permanently frozen to the edges.
No running water (apart from accasional trickles from thaw-pods) was noted in any of the streams in the entire valley system. This was quite different from the summer of 1957-58, when in January large streams were running into the east and west ends of Lake Vida. The the west of Lake Vashka a stream has, in other years, made a deep cut through the moraines, which would require a considerable flow; but this year no water was running. Therefore the attempt to measure the inflow into Lake Vashka (from which no water flows out) was curtailed. Even some of the small shallow lakes in the valley system remained ice-covered.
Wind
Constant winds, relatively high temperatures and low precipitation are characteristic of the dry-valleys.
The wind at the main bases averaged 8.4 miles per hour. The highest wind-run over a 24 hour period was 24 miles per hour. The highest gust was not recorded, but it probably exceeded 60 Knots: The hand aremometer, capable of recording winds up to this velocity blew to pieces on January 24.
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In the wright Valley, which is long and narrow and confined for the most part between 5000 feet walls, the winds at the western end blew either directly up or down valley. They tended to follow a rhythm with easterlies blowing during the afternoon and westerlies during the morning. Easterly winds prevailed in the eastern part of the valley.
Wind in the Victoria Valley system immediately to the north did not follow this pattern; it was invariably from the east throughout the length of the area.
That the easterly wind is predomenant in the Lake Vida area can he deduced from the conformation of the barchan sand dunes to the north of the lake.
The heaviest winds at Lake Vashka came from the south. It must he understood however that the general picture of wind flow in this mountainous region is governed largely by orographical features.
Precipitation
Snow fell at valley-floor level on twelve days. On most occasions it melted after a few hours, but twice it remained for several days.
Less precipitation occurred in the vicinity of Lake Vashka than in the areas immediately to the east and west - again the results of the orographical wind complex.