Western disturbances vs Non-western disturbances days winter precipitation

Abstract

While studying the Western Disturbances (WDs) and associated precipitation forming mechanism in changing time, we found that there is significant amount of precipitation received during Non-WDs days too. In addition, it is also highlighted that all the WDs don’t precipitate. And hence cumulative winter precipitation is kind of summation of all the available precipitation and NOT only of WDs days’ precipitation. Thus here understanding of WDs vs Non-WDs days precipitation dynamics, linkages and changes in last three decades are deliberated. Threshold for evaluating non-precipitating and precipitating day(s) is chosen as < 0.1 mm/d and = or > greater than 0.1 mm/d, respectively. The present finding shows decreasing trend (p-value 0.039) of WDs days precipitation and intriguingly increasing trend (p-value 0.57) of Non-WDs days precipitation. These trends, though statistical not significant, are based on Mann–Kendall test. Further, Non-WDs days precipitation over the western Himalayas (WH) is less studied and researched. Thus dynamics of WDs vs Non-WDs precipitating days precipitation is evaluated and corresponding precipitation and moisture sources days are assessed. As knowingly, WDs precipitation is mainly from western sources and Arabian Sea (AS); whereas Non-WDs days precipitation derive moisture from Bay of Bengal (BoB). Present work presents preliminary investigation for Non-WDs days precipitation.