A climatological satellite view of marine cold air outbreaks in the northeast Atlantic

Abstract

Given the high rate of sea ice loss and the Arctic amplification, the dynamical processes responsible for airmass transport into or out of the Arctic, thus affecting the seasonal melt and recovery of sea ice, need to be understood and scrutinized from different observational perspectives. In a classical, rather binary view of transport “into or out of the Arctic”, a lot of attention in the recent years has rightfully been given on understanding the role of heat and moisture transport into the Arctic in regulating the sea ice melt. However, the cold and dry Arctic airmasses with long residence times are more than occasionally transported out of the Arctic over the open ocean waters, creating one of the most spectacular air mass transformations: the marine cold air outbreaks (MCAOs). The most tangible manifestation of MCAOs are the convectively rolled, narrow cloud streets formed over open water off the edges of the Arctic sea ice in the Nordic and Barents Seas, seen vividly in visible satellite imageries. MCAOs can also locally influence the onset of sea ice melt as they often happen in spring.   By combining nearly 20 years of remotely sensed data from the hyperspectral Atmospheric Infrared Sounder (AIRS), the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Clouds and the Earth’s Radiant Energy System (CERES) instruments onboard NASA’s Aqua satellite, this study presents a climatological view of the vertical structure of atmosphere and the cloud radiative effects during MCAOs in the northeast Atlantic.