Preprints
https://doi.org/10.5194/acp-2021-609
https://doi.org/10.5194/acp-2021-609

  18 Aug 2021

18 Aug 2021

Review status: this preprint is currently under review for the journal ACP.

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

Carolina Viceto1, Irina V. Gorodetskaya1, Annette Rinke2, Marion Maturilli2, Alfredo Rocha1, and Susanne Crewell3 Carolina Viceto et al.
  • 1Department of Physics & Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Aveiro, 3810-193, Portugal
  • 2Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), Potsdam, 14473, Germany
  • 3Institute for Geophysics and Meteorology, University of Cologne, Cologne, 50969, Germany

Abstract. Recently, a significant increase in the moisture content has been documented over the Arctic, where both local contributions and poleward moisture transport from lower latitudes can play a role. This study focuses on the anomalous moisture transport events confined to long and narrow corridors, known as atmospheric rivers (ARs) which are expected to have a strong influence on Arctic moisture amounts, precipitation and energy budget. During the two concerted intensive measurement campaigns, Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) and the Physical feedbacks of Arctic planetary boundary layer, Sea ice, Cloud and AerosoL (PASCAL), which took place from May 22 to June 28, 2017, at and near Svalbard, three high water vapour transport events were identified as ARs, based on two tracking algorithms: on 30 May, 6 and 9 June. We explore in detail the temporal and spatial evolution of the events identified as ARs and the associated precipitation patterns, using measurements from the AWIPEV research station in Ny-Ålesund, satellite-borne measurements, several reanalysis products (ERA5, ERA-Interim, MERRA-2, CFSv2 and JRA-55) and HIRHAM5 regional climate model. Results show that the tracking algorithms detected the events differently partly due to differences in spatial resolution, ranging from 0.25 to 1.25 degree, in temporal resolution, ranging from 1 hour to 6 hours, and in the criteria used in the tracking algorithms. Despite being consecutive, these events showed different synoptic evolution and precipitation characteristics. The first event extended from western Siberia to Svalbard, causing mixed-phase precipitation and was associated with a retreat of the sea-ice edge. The second event a week later had a similar trajectory and most precipitation occurred as rain, although in some areas mixed-phase precipitation or only snowfall occurred, mainly over the north-eastern Greenland’s coast and northeast of Iceland and no differences were noted in the sea-ice edge. The third event showed a different pathway extending from north-eastern Atlantic towards Greenland, and then turning southeastward reaching Svalbard. This last AR caused high precipitation amounts in the east coast of Greenland in the form of rain and snow and showed no precipitation in Svalbard region. The vertical profiles of specific humidity show layers of enhanced moisture, simultaneously with dry layers during the first two events, which were not captured by all reanalysis datasets, while the model misrepresented the entire vertical profiles. Regarding the wind speed, there was an increase of values with height during the first and last events, while during the second event there were no major changes in the wind speed. The accuracy of the representation of wind speed by the reanalyses and the model depended on the event. This study shows the importance of both the Atlantic and Siberian pathways of ARs during spring-beginning of summer in the Arctic, AR-associated strong heat and moisture increase as well as precipitation phase transition, and the need of using high spatiotemporal resolution datasets when studying these intense short duration events.

Carolina Viceto et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-609', Anonymous Referee #1, 05 Sep 2021
  • RC2: 'Comment on acp-2021-609', Anonymous Referee #2, 17 Sep 2021
  • RC3: 'Comment on acp-2021-609', Anonymous Referee #3, 20 Sep 2021

Carolina Viceto et al.

Carolina Viceto et al.

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Short summary
Here we focus on anomalous moisture transport events known as atmospheric rivers (ARs). During the ACLOUD/PASCAL campaigns, three ARs were identified: 30 May, 6 and 9 June. We explore their spatiotemporal evolution and precipitation patterns, using measurements, reanalyses and a model. This study shows the importance of the Atlantic and Siberian pathways during spring/summer in the Arctic, AR-associated heat/moisture increase, precipitation phase transition, and using high resolution datasets.
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