Measurements of underground and underwater temperatures by quartz thermometers at Syowa Station, East Antarctica

Abstract

Eight-months' observation of underground temperature was made by specially designed quartz thermometers in a 20m borehole at Syowa Station, East Antarctica. The underground temperature at 5m depth showed a quasisinusoidal change of 5.47℃ from -4.89℃ to -10.36℃. The above change became smaller to 1.58℃ in the range of -7.73℃∿-9.31℃ at 10m depth, and became further smaller to 0.20℃ in the range of -8.17℃∿-8.37℃ at 20m depth. In comparison with the seasonal variation of air temperature, there was a phase delay of about 90 days at 5m depth and about 290 days at 20m depth. The effect of the seasonal variation of air temperature on that of underground temperature can be estimated as less than 0.01℃ at the depth of 33.8m when exponential decay against depth is assumed to have resulted from such effect. Six-months' observation of sea-water temperature was also made at 7m depth under the ice-cover of the coast of Nisi-no-ura Cove. The observation revealed a gradual increase of temperature from -1.63℃ in June to -1.48℃ in November at an approximate rate of 0.9×10^℃/day. Superposed on the above longterm trend, there was a sequence of short-term (10-30 days) variations of 0.05-0.10℃ which was characterized by the abrupt increase and the subsequent gradual decrease of temperature.