Modulation of North Atlantic atmospheric rivers by the Gulf Stream

ABSTRACT Extreme precipitation and wind events in Western Europe are often driven by atmospheric rivers (ARs) developing over the North Atlantic Ocean. Even though research has explored AR variability in relation to large‐scale atmospheric dynamics and the North Atlantic Storm Track, gaps remain in understanding how oceanic variability influences AR activity, particularly within the eddy‐rich environment of the Gulf Stream extension. The enhanced ocean heat transport and mesoscale eddy activity associated with this western boundary current can influence large‐scale dynamics, modulate moisture availability in the lower atmosphere, and potentially control the AR activity downstream. In this study, we evaluated ocean mesoscale features, oceanic heat supply, and surface heat fluxes in the Gulf Stream extension region at monthly time‐scales. We assessed their downstream impact on AR activity using state‐of‐the‐art observational datasets. Our analysis identified winter and spring as the key seasons for interactions between Gulf Stream conditions and ARs. Higher ocean heat transport and mesoscale sea‐surface height (SSH) meandering were associated with a northward shift in downstream AR activity and a positive North Atlantic Oscillation (NAO) pattern, although the atmospheric response is weaker in the latter case. In contrast, stronger than average surface heat fluxes in the Gulf Stream were linked to a southward shift of ARs and a strong negative NAO pattern, suggesting a dominant atmospheric influence that enhanced moisture availability and modulated North Atlantic dynamics. These results show that the Gulf Stream plays an important role in controlling the latitudinal variability of ARs over the Euro‐Atlantic sector during winter and spring.