Atmospheric rivers and associated precipitation patterns during the ACLOUD and PASCAL campaigns near Svalbard (May–June 2017): case studies using observations, reanalyses, and a regional climate model

Abstract. Recently, a significant increase in the atmospheric moisture content has been documented over Arctic, where both local contributions and poleward transport from lower latitudes can play role. This study focuses on anomalous events confined to long narrow corridors, known as rivers (ARs), which are expected have strong influence Arctic amounts, precipitation, energy budget. During two concerted intensive measurement campaigns – CLoud Observations Using airborne measurements during polar Day (ACLOUD) Physical feedbacks of planetary boundary layer, Sea ice, Cloud AerosoL (PASCAL) that took place at near Svalbard, three high-water-vapour-transport were identified ARs, based tracking algorithms: 30 May event, 6 June 9 2017 event. We explore temporal spatial evolution ARs associated precipitation patterns detail using French (Polar Institute Paul Emile Victor) German (Alfred Wegener for Polar Marine Research) Research Base (AWIPEV) Ny-Ålesund, satellite-borne measurements, several reanalysis products (the European Centre Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA) Interim (ERA-Interim); ERA5 reanalysis; Modern-Era Retrospective analysis Applications, version 2 (MERRA-2); Climate Forecast System (CFSv2); Japanese 55-Year Reanalysis (JRA-55)), HIRHAM regional climate model 5 (HIRHAM5). Results show algorithms detected differently, is partly due differences resolution well criteria used algorithms. The first event extended western Siberia caused mixed-phase was with retreat sea-ice edge. second 1 week later, had similar trajectory, most occurred rain, although or only snowfall some areas, mainly coast north-eastern Greenland north-east Iceland, no noted third showed different pathway extending Atlantic towards before turning south-eastward reaching Svalbard. last AR high amounts east form rain snow Svalbard region. vertical profiles specific humidity layers enhanced concurrent dry not captured by all datasets, whereas HIRHAM5 misrepresented levels. There an wind speed height events, there major changes accuracy representation reanalyses depended objective this paper build knowledge detailed case studies, purpose performing long-term analysis. Thus, we adapted detection algorithm analysed how it datasets (observational, reanalyses, model) suitable dataset, their impacts terms precipitation. shows importance Siberian pathways spring beginning summer Arctic; significance AR-associated heat increase, phase transition; requirement high-spatio-temporal-resolution when studying these intense short-duration events.