Preprints
https://doi.org/10.5194/tc-2022-254
https://doi.org/10.5194/tc-2022-254
 
02 Jan 2023
02 Jan 2023
Status: this preprint is currently under review for the journal TC.

Revisiting temperature sensitivity: How does Antarctic precipitation change with temperature?

Lena Nicola1,2,3, Dirk Notz1,4, and Ricarda Winkelmann2,3 Lena Nicola et al.
  • 1Center for Earth System Research and Sustainability (CEN), Institute of Oceanography, Universität Hamburg, Germany
  • 2Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association, P.O. Box 60 12 03, D-14412 Potsdam, Germany
  • 3University of Potsdam, Institute of Physics and Astronomy, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
  • 4Max Planck Institute for Meteorology, Hamburg, Germany

Abstract. With progressing global warming, snowfall in Antarctica is expected to increase, which could counteract or even temporarily overcompensate ice-sheet mass losses through increased ice discharge, calving and melting. For sea-level projections it is therefore vital to understand the processes determining snowfall changes in Antarctica. Here we revisit the relationship between Antarctic temperature changes and precipitation changes, identifying and explaining regional differences and deviations from the theoretical approach based on the Clausius-Clapeyron relationship. Analysing the latest estimates from global (CMIP6) and regional (RACMO2.3) model projections, we find an average increase of 5.5 % in annual precipitation over Antarctica per degree of warming, with a minimum sensitivity of 2 % K-1 near Siple Coast, and a maximum sensitivity > 10 % K-1 at the East Antarctic Plateau region. This large range can be explained by the prevailing climatic conditions, with local temperatures determining the Clausius-Clapeyron sensitivity that is counteracted in some regions by the prevalence of the coastal wind regime. We compare different approaches of deriving the sensitivity factor, which in some cases can lead to sensitivity changes of up to 7 % for the same model. Importantly, local sensitivity-factors are found to be strongly dependent on the warming level, suggesting that some ice-sheet models which base their precipitation estimates on parameterizations derived from these sensitivity factors might overestimate warming-induced snowfall changes, particularly in high-emission scenarios. This would have consequences for Antarctic sea-level projections for this century and beyond.

Lena Nicola et al.

Status: open (until 27 Feb 2023)

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Lena Nicola et al.

Lena Nicola et al.

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Short summary
For future sea-level projections, it will remain an important approach to approximate Antarctic precipitation increases through temperature-scaling approaches, as coupled ice-sheet simulations with regional climate models remain computationally expensive, especially on multi-centennial timescales. We here revisit the relationship between Antarctic temperature and precipitation using different scaling approaches, identifying and explaining regional differences.