Linking the North Atlantic Oscillation to winter precipitation over the Western Himalaya through disturbances of the subtropical jet

Abstract Winter (December to March) precipitation is vital the agriculture and water security of Western Himalaya. This largely brought region by extratropical systems, known as western disturbances (WDs), which are embedded in subtropical jet. In this study, using seventy years data, it shown that during positive phases North Atlantic Oscillation (NAO+) jet significantly more intense than negative (NAO−). Accordingly, NAO affects WD behaviour on interannual timescales: NAO+ periods, WDs average 20% common 7% NAO− periods. results 40% moisture flux entering impinging Himalaya an increase winter 45% compared NAO−. Using empirical orthogonal function (EOF) analysis, variability causally linked over India—latitudinal variation waviness downstream, whereas its tilt strength shear downstream. These used construct a simple linear model can skilfully predict north India at lead time one month.