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Air temperature environment on the debris- covered area of Lirung Glacier, Langtang Valley, Nepal Himalayas

2000; International Association of Hydrological Sciences; Linguagem: Inglês

0144-7815

Koji Fujita, Akiko Sakai,

Climate change and permafrost

Meteorological observations have been carried out for different surface covers (grass, debris-free glacier and rock-covered glacier ice in Langtang Valley, Nepal Himalayas. Change in the daily mean lapse rate over debris-covered ice shows a significantly larger fluctuation compared with over debris-free ice. An analysis of the daily mean lapse rate reveals that a low (high) lapse rate appeared under dry (wet) conditions on the debris-covered area even though the opposite result was expected for the lapse rate of a free atmosphere. It is considered that less evaporation under dry condition would bring about high surface and then warm air temperatures. Diurnal changes in the lapse rate over debris-covered ice suggests that the air temperature changes less over the debris-covered ice than over grassland and debris-free ice. Perhaps heat stored in the debris layer would prevent large diurnal changes in air temperature. Both seasonal and diurnal changes in lapse rate suggest the strong effect on air temperature of the complex topography of the debris- covered area and the presence of the debris layer. This fact suggests that air temperature cannot be simply estimated by a constant lapse rate as in previous studies.