A study on frequency of western disturbances and precipitation trends over Jammu & Kashmir, India : 1980-2019

Abstract

A study has been conducted on frequency of western disturbances (WDs) and variability of precipitation over J&K for the period 1980 to 2019. The frequency of WD’s from November to April during study period was determined and results showed that total 600 WD’s cases were observed during the period 1980-2019. It has been observed that on an average during the month of November and December, 2 moderate to severe WD’s cases were observed and 3 cases during January, February, March and April respectively. Trends of WD and Precipitation over different months were analyzed using Innovative trend analysis, Mekendal test and linear regression analysis. The analysis showed that WD frequencies showed decreasing significant trend (p<0.01) during November and March with slope values -0.610 and -2.748 respectively and increasing trends were observed during February with slope value 2.795 (p<0.01) and January with slope value 0.417 but were non significant. The results of the Mann–Kendall statistical tests for the monthly precipitation series over the period 1980-2019 showed significant decreasing trends for Kupwara in the month of December and March with a slope value  of  -2.450 and -2.947 mm/month respectively while Gulmarg station showed decreasing significant trends for the month of March with slope value of -6.947 mm/month. No significant trends were observed for other stations for different months although some stations showed increased trends while some showed decreasing trends. The results of  Innovative trend analysis showed that Gulmarg and Baderwah stations showed decreasing significant trends with slope ranging from -0.727 to -7.806 mm/month except February month (Baderwah) which showed increasing trend with slope 1.058 significant at p<0.01. Increasing trends were observed during February and april months over Kukernag station with slope 1.267 and 2.348 and decreasing trend during December and march. Banihal and Batote also showed increasing significant trends for the month of February with slope value 2.795 and 2,231 mm/month respectively. As shown, only Kupwara station had the significant decreasing trend in December and March with a slope of -1.746 and -4.116 mm/month respectively. All other stations had shown no significant trends. The correlation between average precipitation of all the stations and total WD frequency was done and results showed positively correlation between precipitation and WD frequency with R² value 0.55.