The Sub-Regional Classification of Pakistan’s Winter Precipitation Based On Principal Components Analysis

Wintertime (December – March, DJFM) rainfall contributes about 30 % to the annual total rainfall of Pakistan with some areas in west and southwest of the country being entirely dependent on winter rains. Winter precipitation plays a pivotal role towards the agriculture, water reservoirs, hydroelectric power generation and ecosystems of the country. Pakistan owing to its peculiar topographic features exhibits a distinctively different spatial rainfall distribution from north to south. In this study 30-year monthly and seasonal (December – March, DJFM) total rainfall data of 35 data sites over a period 1976-2005 have been used to find out spatial rainfall distribution and hence identify the sub-regional rainfall distribution patterns across the country. The Principal Components Analysis (PCA) has been performed to delineate the spatial rainfall variance and pattern from within the data stations which identified the six different spatial rainfall sub-regions within Pakistan.