An analytical study of variations in the monsoon patterns over Pakistan

In the recent era, the climate change has not only triggered the extreme weather events but also brought uncertainties in the behavior of certain weather phenomenon. These variations in the weather patterns are very significant in their consequences. So to enhance the understanding of these uncertainties, the study of these variations is of utmost importance. This study is carried out to investigate the variations in the precipitation patterns over the major monsoon belt of Pakistan during the summer monsoon period. Frequency of extreme precipitation events, onset, withdrawal, duration of monsoon season, total amount of rainfall during the season and total number of rainy days all these parameters are the key factors not only in understanding the uncertainties caused by the climate change but also from the socio-economic point of view. Daily rainfall observed data is used to compute the above mentioned parameters of the monsoon system. Islamabad has a high frequency of extreme events with rainfall 50 mm, 100 mm or more per day, as compared to the other stations of the same monsoon belt. Southeastern part of the country experiences a trend towards increasing frequency of such extreme events during the last decade. In the northeast, Lahore is the only station where the duration of the monsoon season is increasing significantly. Southeastern monsoon belt has a suppressing trend in terms of the duration of the summer monsoon. Generally the northeastern stations show a direct relationship between the variation of the total amount of rainfall and number of rainy days. Stations located in the southeastern monsoon belt of the country exhibits a trend towards the occurrence of extreme precipitation events as the number of rainy days are not increasing accordingly with the amount of rainfall.