How does the ice sheet surface mass balance relate to snowfall? Insights from a ground-based precipitation radar in East Antarctica
Local surface mass balance (SMB) measurements are crucial for understanding changes in the total mass of the Antarctic Ice Sheet, including its contribution to sea level rise. Despite continuous attempts to decipher mechanisms controlling the local and regional SMB, a clear understanding of the...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-06-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/12/1987/2018/tc-12-1987-2018.pdf |
| Summary: | Local surface mass balance (SMB) measurements are crucial for understanding
changes in the total mass of the Antarctic Ice Sheet, including its
contribution to sea level rise. Despite continuous attempts to decipher
mechanisms controlling the local and regional SMB, a clear understanding of
the separate components is still lacking, while snowfall measurements are
almost absent. In this study, the different terms of the SMB are quantified
at the Princess Elisabeth (PE) station in Dronning Maud Land, East
Antarctica. Furthermore, the relationship between snowfall and accumulation at
the surface is investigated. To achieve this, a unique collocated set of
ground-based and in situ remote sensing instrumentation (Micro Rain Radar,
ceilometer, automatic weather station, among others) was set up and operated for
a time period of 37 months. Snowfall originates mainly from moist and warm
air advected from lower latitudes associated with cyclone activity. However,
snowfall events are not always associated with accumulation. During 38 % of
the observed snowfall cases, the freshly fallen snow is ablated by the wind
during the course of the event. Generally, snow storms of longer duration and
larger spatial extent have a higher chance of resulting in accumulation on a local scale, while shorter events usually result in ablation (on average 17
and 12 h respectively). A large part of the accumulation at the station
takes place when preceding snowfall events were occurring in synoptic
upstream areas. This fresh snow is easily picked up and transported in
shallow drifting snow layers over tens of kilometres, even when wind speeds
are relatively low ( < 7 ms<sup>−1</sup>). Ablation events are mainly related to
katabatic winds originating from the Antarctic plateau and the mountain
ranges in the south. These dry winds are able to remove snow and lead to a
decrease in the local SMB. This work highlights that the local SMB is
strongly influenced by synoptic upstream conditions. |
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| ISSN: | 1994-0416 1994-0424 |