Response of Early Winter Precipitation and Storm Activity in the North Atlantic–European–Mediterranean Region to Indian Ocean SST Variability

We investigate the response of winter precipitation and storm activity in the North Atlantic–European–Mediterranean region (NAEM) to the Indian Ocean Dipole (IOD) from 1979 to 2024. We observe a positive NAO-like pattern over NAEM, which appears in December and shifts eastward through February. IOD further modulates precipitation by inducing changes in total precipitation, event frequency, and wet spell duration. The strength of the observed teleconnection is primarily significant in December. Additionally, we observe a reduction in cyclone activity in December over the East Atlantic and Western Mediterranean. These changes in cyclone track density are primarily driven by variations in the Eady Growth Rate, which are linked to enhanced vertical wind shear associated with a strengthened meridional temperature gradient over the NAEM. The results underscore a significant remote impact of the IOD on early winter hydro-climate variability over the NAEM region, offering a potential value for improving sub-seasonal to seasonal prediction.