On the space-time patterns of precipitation in the Himalayan range: a synthesis
Ana P. Barros (1)
(1) Duke University
6th International GAME Conference On the space-time patterns of precipitation in the Himalayan range: a synthesis Ana P. Barros, Duke University, Box 90287, 2457 CIEMAS Bldg., Durham, NC 27708 [email:barros@duke.edu; phone:919-660-5539] Abstract Through diagnostic studies combining space-time scaling analysis of ground-based hydrometeorological observations, radiosonde profiles, METEOSAT and TRMM satellite data, as well as simulations using a Cloud Resolving Model, we were able to identify and characterize the dominant weather systems and associated precipitation processes in the Central Himalayas: a) monsoon depressions; b) wintertime storms; c) stationary orographic gravity waves; and d) ridge-locked convection. Our analysis shows that while the first two regimes are associated mainly with large-scale circulations, and exhibit strong inter-annual variability in frequency, intensity and spatial track; the second two regimes control the diurnal cycle during the monsoon and the spatial distribution of precipitation year round. Therefore, a synthesis of Himalayan hydrometeorology is proposed that relies on three principal modes of space-time variability: 1) an inter-seasonal mode linked to large-scale dynamics that explains infrequent events producing significant amounts of precipitation over one-three day periods (wintertime storms and monsoon depressions); 2) a regional mode linked to ocean-land-atmosphere interactions over Northern-India and the Bay of Bengal at time-scales of days to weeks consistent with the succession of rainy and dry episodes during the break and active phases of the monsoon; and 3) an orographic mode that explains the spatial variability of the diurnal cycle on the Himalayan range during the monsoon.