Item

Abstract

The South Asian jet wave train, along which the disturbances originating from the North Atlantic propagating to the western North Pacific, builds a bridge between the North Atlantic disturbance and East Asian winter climate. The discovery of its trigger regimes, propagating processes and climate impacts may help improving the prediction of winter climate. The wave train is equivalently barotropic and strongest in the upper troposphere, with its daily evolution dominated by the intraseasonal (10–30 day) time scale. The northwest–southeast oriented negative phase of NAO can stimulate the wave train easily. The energy is rooted in the lower troposphere over the high-latitude North Atlantic, and the key Rossby wave source is excited over the western Mediterranean Sea via vortex stretching by abnormal divergence. When the disturbance propagates to East Asia along the South Asian jet wave train, it could either deepen the Indian Burma trough, or trigger the abnormal western North Pacific anticyclone, which are zonally offset each other by a quarter wavelength. Both of them transport abundant moisture to South China, intensifying the winter stationary front and the inducing the winter extreme rainfall, with the rainfall location lying over either Souheast China or the lower reach of Yangtze River valley.