L−moment Based Regional Frequency Analysis of Annual Maximum Relative Humidity Across Pakistan

Abstract

Climate change has significantly impacted regional weather patterns in Pakistan, leading to an increase in the frequency and intensity of extreme weather events, such as heatwaves, droughts, and floods. This study aimed to investigate the regional frequency analysis of extreme relative humidity across Pakistan, identify potential geographically related trends, and estimate possible frequencies associated with extreme relative humidity in distinct regions. The data were collected from 24 meteorological stations. Discordance measures were used to evaluate distinct sites in the region, with GAWADAR and KARACHI exhibiting the highest discordance values. The study region was divided into three homogeneous regions based on geographic and statistical measures to verify the heterogeneity statistics. The L−moment ratio diagram and goodness−of−fit statistic identified suitable distributions for each region, with the generalized extreme value and Pearson type III distributions proving to be most effective in the first region. The second region was best represented by the generalized extreme value and Weibull distributions, whereas the third region was most accurately characterized by the generalized log-normal and polynomial density−quantile III distributions. These results offer valuable insights into the spatial patterns of humidity extremes, potentially supporting efforts in climate change adaptation and flood risk management.