Abstract ID: 3.8360 | Accepted as Talk | Talk/Oral | TBA | TBA

The central-eastern Himalayas (CEH), a key high-altitude barrier on the southern edge of the TP, experiences concentrated summer rainfall and is a crucial water source for Asian countries. What determines the variation in the summer precipitation of the CEH has not been investigated. Here, we investigated the relationship between the Central-Eastern Himalayas summer precipitation and all kinds of signals for the oceans. Analysis of long-term observations and reanalysis data revealed that the summer North Atlantic Oscillation (SNAO) has driven a positive summer precipitation in the CEH. The abnormal circulation in Indian subcontinent due to SNAO met with the south slope of Himalayas. The abnormal circulation caused a topographic mechanical forcing in the CEH. The topography forces the abnormal horizontal winds to generate a strong climb flow component, driving changes in the precipitation distribution. Experiments with removing the plateau topographic features show that the original positive precipitation distribution shifts into a dipole-like pattern. The CEH was dominated by negative precipitation distribution after removing topography. The negative distribution in the CEH were directly governed by the upstream atmospheric circulation from the Atlantic ocean. Thus, accurate predictions of summer precipitation in the CEH should consider both topographic dynamic forcing and the upstream Atlantic ocean signal changes.