Sensitivity of the current Antarctic surface mass balance to sea surface conditions using MAR
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Published:2018-12-07
Issue:12
Volume:12
Page:3827-3839
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ISSN:1994-0424
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Container-title:The Cryosphere
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language:en
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Short-container-title:The Cryosphere
Author:
Kittel ChristophORCID, Amory CharlesORCID, Agosta CécileORCID, Delhasse AlisonORCID, Doutreloup SébastienORCID, Huot Pierre-Vincent, Wyard Coraline, Fichefet Thierry, Fettweis XavierORCID
Abstract
Abstract. Estimates for the recent period and projections of the Antarctic surface mass
balance (SMB) often rely on high-resolution polar-oriented regional climate
models (RCMs). However, RCMs require large-scale boundary forcing fields
prescribed by reanalyses or general circulation models (GCMs). Since the
recent variability of sea surface conditions (SSCs, namely sea ice
concentration, SIC, and sea surface temperature, SST) over the Southern Ocean
is not reproduced by most GCMs from the 5th phase of the Coupled Model
Intercomparison Project (CMIP5), RCMs are then subject to potential biases.
We investigate here the direct sensitivity of the Antarctic SMB to SSC
perturbations around the Antarctic. With the RCM “Modèle Atmosphérique
Régional” (MAR), different sensitivity experiments are performed over
1979–2015 by modifying the ERA-Interim SSCs with (i) homogeneous
perturbations and (ii) mean anomalies estimated from all CMIP5 models and two
extreme ones, while atmospheric lateral boundary conditions remained
unchanged. Results show increased (decreased) precipitation due to
perturbations inducing warmer, i.e. higher SST and lower SIC (colder,
i.e. lower SST and higher SIC), SSCs than ERA-Interim, significantly
affecting the SMB of coastal areas, as precipitation is mainly related to
cyclones that do not penetrate far into the continent. At the continental
scale, significant SMB anomalies (i.e greater than the interannual
variability) are found for the largest combined SST/SIC perturbations. This
is notably due to moisture anomalies above the ocean, reaching sufficiently
high atmospheric levels to influence accumulation rates further inland.
Sensitivity experiments with warmer SSCs based on the CMIP5 biases reveal
integrated SMB anomalies (+5 % to +13 %) over the present climate
(1979–2015) in the lower range of the SMB increase projected for the end of
the 21st century.
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Water Science and Technology
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