Phys.org October 14, 2024
Atmospheric rivers (ARs) are key agents in distributing extratropical precipitation and transporting moisture poleward. Climate models suggest an increase in AR activity in the extratropics over the past four decades. However, analyses indicate a poleward shift of ARs during boreal winter in both hemispheres. Researchers at UC Santa Barbara demonstrated that low-frequency sea surface temperature variability in the tropical eastern Pacific exhibited a cooling tendency since 2000 that played a key role in driving global AR shift, mostly over extratropical oceans. This mechanism also operated on interannual timescales, controlled by the El Niño–Southern Oscillation, and was less pronounced over the Southern Ocean due to weaker eddy activity during austral summer. The findings highlight the sensitivity of ARs to large-scale circulation changes driven by both internal variability and external forcing in current and upcoming decades… read more. Open Access TECHNICAL ARTICLE

Observed statistical relationship between detrended AR frequency and circulation. Credit: Science Advances, 11 Oct 2024, Vol 10, Issue 41