Non-stationary influence of the North Atlantic Oscillation on summer precipitation in the Central-Eastern Himalayas

Abstract Understanding the interannual variability of summer precipitation across the Central-Eastern Himalayas (CEH) is essential for guiding efficient water management and supporting socio-economic development in South Asia. However, the mechanisms through which climate variability shapes CEH summer precipitation variability remain insufficiently understood. Summer precipitation in the CEH is modulated by multiple climate factors, with the El Niño–Southern Oscillation as a sustained weak force and the summer North Atlantic Oscillation (SNAO) exerting non-stationary effects. The SNAO can trigger an anomalous anticyclone over South Asia, directing low-level winds toward the Himalayas’ southern slopes, inducing precipitation anomalies through topographic mechanical forcing. The position shift of the SNAO-driven anomalous anticyclone to the south of the CEH modulates the coupled and decoupled relationship between SNAO and CEH summer precipitation variability. Therefore, understanding the dynamic links between the SNAO and CEH summer precipitation is key to enhancing precipitation prediction accuracy.