Climatic characteristics of temperature and precipitation of Bhutan

Abstract

Bhutan is a land locked mountainous Country situated on the southern slopes of the eastern Himalayas between 26 degrees 70' - 28 degrees 35' N Latitudes and 88 degrees 50' - 92 degrees 30' E Longitudes. Bhutan has a Spatially diversified climate- tropical in Southern plains, cool winter and hot summer in central valleys and severe winter and cool summer in the mountains. Extremely non-uniform topography makes the climate of Bhutan very complex. More over, Bhutan is situated in the periphery of the extra-tropical circulation and Asian monsoon Circulation in the north and south respectively. These situations make the climate of Bhutan more complex. An attempt has been made to study the characteristics of the climate of Bhutan using the data of temperature and precipitation of 44 stations for the years 1990-1999. Annual profile of monthly minimum and maximum temperature shows the unimodal character attaining maximum in July and minimum in January for most of the stations of Bhutan. Extreme highest temperature was 37.2 degrees C at Phuntsholing in the southwest Bhutan and extreme lowest temperature is -8.2 degrees C at Drukgyel Dzong in the west central Bhutan. Spatial distribution of temperature shows that the mountainous areas of the central, west central and northern part of Bhutan are characterized by low temperature and the Southern valleys by high temperature. Annual profile of monthly precipitation manifests the unimodal nature attaining maximum mostly ill July and minimum in January. The highest annual precipitation was 5866 mm at Sipsoo and lowest annual precipitation of 628 mm at Gidakom. The central and northern part of Bhutan has relatively low precipitation. The country average precipitation shows that Bhutan gets 1679.4 mm of annual precipitation of which about 70 % occurs in the monsoon season and 19.9% in the pre-monsoon season. The yearly time series of country average monsoon precipitation for 10 years shows a variation with timescale of 3-4 years with a coefficient of variation (CV) of 5.5%. Comparison of monsoon precipitation of Bhutan with All India Monsoon Precipitation (AIMP) shows that the former undergoes more or less opposite phase of variations with respect to AIMP. The correlation analysis shows negative correlation with correlation coefficient of -0.64 which is significant at 0.05 levels.