Precipitation variability in central Himalayas and its relation to Northern Hemisphere temperature

Agriculture, industry and hydroelectric power in south Asia are heavily dependent on the performance of the summer (June to September) monsoon rainfall, which provides 75—90% of the annual rainwater over most parts of the area. A weak monsoon year generally corresponds to low crop yields. And strong monsoon usually produces abundant crops, although too much rainfall may produce devastating floods. However, modeling efforts to forecast the monsoon have met with only moderate success1]. Prev…

Precipitation variability in central Himalayas and its relation to Northern Hemisphere temperature

A 149.8-m-long ice core was drilled at the accumulation area of Dasuopu glacier (28°23′N, 85°43′E, 7100 m a.s.l.) in the central Himalayas in 1997. The ice core was analyzed continuously for stable isotopes (δ ¹⁸O), cations (Na⁺, K⁺, Mg²⁺, Ca²⁺) and anions (Cl⁻, SO ₄ ⁻ , NO ₃ ⁻ ) throughout the core. Cycles indicated by δ¹⁸O, cations and anions were identified and counted as seasonal fluctuations as annual increment from maximum to maximum values. Reconstructed 300-year annual net accumulation from the core reveals a major precipitation trend for the central Himalayas with an average precipitation 750 mm per year. The trend, separated from the time series, shows a strong correlation to global temperature. Generally, as northern global temperature increases 0.1δC, the accumulation decreases about 80mm and vise versa. This may suggests that monsoon precipitation in Himalayas have decreased continuously in past decade as a response to global warming.