EGU2020-3019
https://doi.org/10.5194/egusphere-egu2020-3019
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Synoptic conditions and atmospheric moisture pathways associated with virga and precipitation over coastal Adélie Land, Antarctica

Nicolas Jullien1,2, Etienne Vignon2, Michael Sprenger3, Franziska Aemisegger3, and Alexis Berne2
Nicolas Jullien et al.
  • 1Department of Geosciences, University of Fribourg, Fribourg, Switzerland (nicolas.jullien@unifr.ch)
  • 2Environmental Remote Sensing Laboratory (LTE), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
  • 3Institute for Atmospheric and Climate Science, ETH Zürich, Zürich, Switzerland

Precipitation falling over the coastal regions of Antarctica often experiences low-level sublimation within the dry katabatic layer. The amount of water that reaches the ground surface is thereby considerably reduced. We investigate the synoptic conditions and the atmospheric transport pathways of moisture that lead to virga – when precipitation is completely sublimated – or actual surface precipitation at Dumont d’Urville (DDU) station, coastal Adélie Land, Antarctica. We combine ground-based radar measurements, Lagrangian back-trajectories, Eulerian diagnostics of extratropical cyclones and fronts as well as with moisture source estimations based on ERA5 reanalyses. Virga periods – corresponding to 36% of the precipitating events – often precede and sometimes follow surface precipitation periods. Pre-precipitation virga, surface precipitation and post-precipitation virga correspond to different phases of the same precipitating system. Precipitation and virga are always associated with the warm front of an extratropical cyclone that sets to the west of coastal Adélie Land but the exact locations of the cyclone and front differ between the three phases. On their way to DDU, the air parcels that ultimately precipitate above the station experience a large-scale lifting across the warm front. The lifting generally occurs earlier in time and farther from the station for virga than for precipitation. It is further shown that water contained in the precipitation falling above DDU during pre-precipitation virga has an oceanic origin farther away (30 degrees more to the west) from Adélie Land than the one that precipitates down to the ground surface.

How to cite: Jullien, N., Vignon, E., Sprenger, M., Aemisegger, F., and Berne, A.: Synoptic conditions and atmospheric moisture pathways associated with virga and precipitation over coastal Adélie Land, Antarctica, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3019, https://doi.org/10.5194/egusphere-egu2020-3019, 2020

Comments on the presentation

AC: Author Comment | CC: Community Comment | Report abuse

Presentation version 1 – uploaded on 05 May 2020 , no comments