Heat exchange at the snow-air interface at the South Pole

Abstract

A surface heat budget has been determined for the geographical south pole on the basis of temperature and radiation data for 1958. From subsurface temperature and density data in the upper 1200 cm of snow, calculations were made of the heat storage. This layer undergoes net cooling from early February to mid-September, the total upward heat flux to the atmosphere being approximately 1720 ly (cal/cm2). There is an indication that the upward flux of heat from the surface becomes progressively less during the winter. On the basis of four successive years of January data, only minor year-to-year differences are noted in the subsurface temperature profiles. During June 1958 the net radiative heat loss from the snow surface averaged 54.8 ly/day, of which 15 percent was made available by cooling of the upper 300 cm of snow and 85 per cent from turbulent exchange of sensible and latent heat r between the atmosphere and snow. For June 1958 the relationship between r and the 10-meter wind speed (U10 and between r and the 2- to 10-meter temperature difference (ΔT/ΔZ( was determined to be, respectively, r = 0.7505U10 × 10 − 6 and r = 0.6301ΔT/ΔZ, where r is in ly/sec, U10 is in cm/sec, and ΔT/ΔZ is in °C/cm. During the month the temperature gradient between 2 and 10 meters above the snow surface averaged +0.11°C per meter. An estimate of the semiannual heat budget of the south pole has been prepared. The net radiation totals −0.97×104 ly in the dark period and −104 ly and −0.13×104 ly during the two periods, respectively. It appears, therefore, that r totals +0.84×104 ly during the period of darkness and +0.44×104 ly during the sunlit period.