Bias in modeled Greenland Ice Sheet melt revealed by ASCAT

محفوظ في:
التفاصيل البيبلوغرافية
الحاوية / القاعدة:The Cryosphere vol. 19, no. 8 (2025), p. 2963
المؤلف الرئيسي: Puggaard, Anna
مؤلفون آخرون: Hansen, Nicolaj, Mottram, Ruth, Nagler, Thomas, Scheiblauer, Stefan, Simonsen, Sebastian B, Sørensen, Louise S, Wuite, Jan, Solgaard, Anne M
منشور في:
Copernicus GmbH
الموضوعات:
الوصول للمادة أونلاين:Citation/Abstract
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100 1 |a Puggaard, Anna  |u Geodesy and Earth Observation, DTU-Space, Technical University of Denmark, Lyngby, Denmark; National Centre for Climate Research, Danish Meteorological Institute (DMI), Copenhagen, Denmark 
245 1 |a Bias in modeled Greenland Ice Sheet melt revealed by ASCAT 
260 |b Copernicus GmbH  |c 2025 
513 |a Journal Article 
520 3 |a The runoff of surface melt is the primary driver of mass loss over the Greenland Ice Sheet. An accurate representation of surface melt is crucial for understanding the surface mass balance and, ultimately, the ice sheet's total contribution to sea level rise. Regional climate models (RCMs) model ice-sheet-wide melt volume but exhibit large variability in estimates among models, requiring validation with observed melt. Here, we explore a novel data processing method from the Advanced SCATterometer (ASCAT) instrument on board the EUMETSAT MetOp satellites, which provides estimates of the spatiotemporal variability of melt extent over the Greenland Ice Sheet between 2007 and 2020. We apply ASCAT wet-snow maps to pinpoint differences in the melt products from three distinct RCMs, where one is forced at the boundary with two different reanalyses. Using automatic weather station (AWS) air temperature observations, we assess how well RCM-modeled melt volume aligns with in situ temperatures. With this assessment, we establish a threshold for the RCMs to identify how much meltwater is in the models before it is observed at the AWSs and ultimately infer the melt extent in the RCMs. We show that applying thresholds, informed by in situ measurements, reduces the differences between ASCAT and RCMs and minimizes the discrepancies between different RCMs. Differences between modeled melt extent and melt extent observed by ASCAT are used to pinpoint (i) biases in the RCMs, which include variability in their albedo schemes, snowfall, turbulent heat fluxes, and temperature, as well as differences in radiation schemes, and (ii) limitations of the liquid water detection by ASCAT, including misclassification in the ablation zone and a temporal melt onset bias. Overall, we find that the RCMs tend to have a later melt onset than ASCAT and an earlier end to the melt season, with a similar but slightly smaller melt area compared to that identified in ASCAT. Biases, however, vary spatially between models and with compensating errors in different regions, suggesting that one RCM can sometimes represent the present-day surface across the entire ice sheet more effectively than the ensemble mean. 
651 4 |a Greenland 
653 |a Bias 
653 |a Estimates 
653 |a Sea level 
653 |a Weather 
653 |a Air temperature 
653 |a Sea level rise 
653 |a Sea level changes 
653 |a Meltwater 
653 |a In situ measurement 
653 |a Glaciation 
653 |a Mass balance 
653 |a Remote sensing 
653 |a Ice 
653 |a Ice sheets 
653 |a Regional climates 
653 |a Automatic weather stations 
653 |a Heat flux 
653 |a Albedo 
653 |a Scatterometers 
653 |a Dielectric properties 
653 |a Data processing 
653 |a Models 
653 |a Ablation 
653 |a Regional climate models 
653 |a Data analysis 
653 |a Greenland ice sheet 
653 |a In situ temperature 
653 |a Snowfall 
653 |a Surface runoff 
653 |a Heat transfer 
653 |a Temperature 
653 |a Climate models 
653 |a Sensors 
653 |a Snow 
653 |a Satellites 
653 |a Environmental 
700 1 |a Hansen, Nicolaj  |u National Centre for Climate Research, Danish Meteorological Institute (DMI), Copenhagen, Denmark 
700 1 |a Mottram, Ruth  |u National Centre for Climate Research, Danish Meteorological Institute (DMI), Copenhagen, Denmark 
700 1 |a Nagler, Thomas  |u Environmental Earth Observation Information Technology (ENVEO) IT GmBH, Innsbruck, Austria 
700 1 |a Scheiblauer, Stefan  |u Environmental Earth Observation Information Technology (ENVEO) IT GmBH, Innsbruck, Austria 
700 1 |a Simonsen, Sebastian B  |u Geodesy and Earth Observation, DTU-Space, Technical University of Denmark, Lyngby, Denmark 
700 1 |a Sørensen, Louise S  |u Geodesy and Earth Observation, DTU-Space, Technical University of Denmark, Lyngby, Denmark 
700 1 |a Wuite, Jan  |u Environmental Earth Observation Information Technology (ENVEO) IT GmBH, Innsbruck, Austria 
700 1 |a Solgaard, Anne M  |u Glaciology and Climate, Geological Survey of Denmark and Greenland (GEUS), Copenhagen, Denmark 
773 0 |t The Cryosphere  |g vol. 19, no. 8 (2025), p. 2963 
786 0 |d ProQuest  |t Continental Europe Database 
856 4 1 |3 Citation/Abstract  |u https://www.proquest.com/docview/3238569811/abstract/embedded/7BTGNMKEMPT1V9Z2?source=fedsrch 
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