Thresholds and Characteristics for Heatwaves and Coldwaves in Nepal Between 1981-2020

Abstract

With continuous climate change and global warming, temperature related hazards like: heatwave and coldwave must be monitored and studied, specially keeping in mind the geographical diverseness of Nepal where temperature related hazards can easily change into disasters. This study covers all the Nepal and with 40 years of statistical and climatological study of heatwaves and coldwaves unlike any other study of its kind. Also, this study attempts to provide nationalized standard criteria for monitoring heatwaves and coldwaves on district levels that has been severely lacking. With aim to determine percentile thresholds for heatwaves and coldwaves respectively and to characterize the past behaviors of both of these waves, this study analyzed the climatology and differences of heatwaves and coldwaves by using percentile method recommended by WMO based on last 40 years (1981-2020) of climatic data from 96 stations widely spread across the country. This study uses percentile method for computation of daily thresholds for heatwaves and coldwaves. Giving emphasis on 95th and 5th percentile value thresholds for heatwaves and coldwaves, these waves were identified. Also, this study extends to examine magnitude, frequency, spatial distribution and statistical comparison of these events.