Spectral Analysis of Monsoonal Precipitation in the Nepal Himalaya

Glaciological Expedition to Nepal, Contribution No. 15

Abstract

Spectral analysis was performed on records of the daily precipitation during the monsoon season of 1973 at stations in the Nepal Himalaya. Through power spectral analysis on the data at 12 stations and also on the areal averaged data (east, central and west Nepal), a predominant periodicity of around 10 days and secondary periodicity of about 5 days are found. Through cross-spectral analysis between these data, the periodicity around 10 days is found to be correlated with large-scale disturbances causing precipitation simultaneously in all of Nepal, and the periodicity of about 5 days seems to be associated with monsoon lows moving westward along the monsoon trough in northern India. The periodicity of around 10 days also seems to be related to the oscillation of the Tibetan High and or level of activity of the monsoon regime over the Indo-Tibetan region.