Droughts over Pakistan: possible cycles, precursors and associated mechanisms

Abstract

In the recent few decades, climate variability had severely affected the socio-economic and environmental conditions worldwide. Frequent shifts in the atmospheric circulation patterns affect large parts of the globe, predominantly the arid and semi-arid regions facing severe to moderate droughts. Therefore, precursors of drought events and their associated mechanisms are important to understand. This study explores the possible cycles and precursor conditions that might be employed for predicting upcoming droughts in Pakistan. Standardize precipitation index and the single Z-index are used to detect and rank the drought years. Moreover, composite analysis is carried out to explore the large-scale circulation anomalies related to extreme drought events. Results demonstrate that extreme drought events are highly correlated with wind patterns and intrinsic weather system in the Pacific and Indian Oceans. This study analyzed air temperature, sea level pressure and geopotential height in the average time-period of January to March, sea surface temperature from October to December, and wind vectors in March to May as precursors that could be employed to predict the occurrence of droughts in Pakistan. This information is of significance for policymakers to plan climate change adaptive measures accordingly.