Abstract
Comment
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Oral
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IACS
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JCMP09 - Ice sheet mass loss: A driver of sea level rise
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Quantification of buffered water storage within the Greenland Ice Sheet using GPS data
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1. Pavel Ditmar*, Department of Geoscience and Remote Sensing,Delft University of Technology,Delft,The Netherlands
2. Jiangjun Ran, Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen,China
3. Michiel R., van den Broeke, Institute for Marine and Atmospheric Research,Utrecht University,Utrecht,The Netherlands
4. Lin Liu, Department of Earth and Environmental Sciences,Faculty of Science,The Chinese University of Hong Kong,Hong Kong,China
5. Roland Klees, Department of Geoscience and Remote Sensing,Delft University of Technology,Delft,The Netherlands
6. Shfaqat Abbas, Khan, Department of Geodesy and Earth Observation,DTU Space?National Space Institute,Technical University of Denmark,Kongens Lyngby,Denmark
7. Twila Moon, National Snow and Ice Data Center,Cooperative Institute for Research in Environmental Sciences,University of Colorado,Boulder,Boulder,CO,USA
8. Jiancheng Li, School of Geosciences and Info-Physics,Central South University,Changsha,China; MOE Key Laboratory of Geospace Environment and Geodesy,School of Geodesy and Geomatics,Wuhan University,Wuhan,China; Hubei Luojia Laboratory,Wuhan University,Wuhan,China
9. Michael Bevis, Division of Geodetic Science,School of Earth Sciences,Ohio State University,Columbus,OH,USA
10. Min Zhong, School of Geospatial Engineering and Science,Sun Yat-sen University,Zhuhai,China
11. Xavier Fettweis, Department of Geography,University of Liege,Liege,Belgium
12. Junguo Liu, Yellow River Research Institute,North China University of Water Resources and Electric Power,Zhengzhou,China; Henan Provincial Key Laboratory of Hydrosphere and Watershed Water Security,North China University of Water Resources and Electric Power,Zhengzhou,China
13. Brice Noel, Department of Geography,University of Liege,Liege,Belgium
14. C. K., Shum, Division of Geodetic Science,School of Earth Sciences,Ohio State University,Columbus,OH,USA
15. Jianli Chen, Department of Land Surveying and Geo-Informatics,The Hong Kong Polytechnic University,Hong Kong,China; Research Institute for Land and Space,The Hong Kong Polytechnic University,Hong Kong,China; Hong Kong Polytechnic University Shenzhen Research Institute,Shenzhen,China
16. Liming Jiang, State Key Laboratory of Geodesy and Earths Dynamics,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences,Wuhan,China; College of Earth and Planetary Science,University of Chinese Academy of Sciences,Beijing,China
17. Tonie van Dam, Department of Geology and Geophysics,College of Mines and Earth Science,University of Utah,Salt Lake City,UT,USA
*Presenting Author
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The study is focused on Buffered Water Storage (BWS) ? the temporal storage of meltwater en route to the ocean ? within the Greenland Ice Sheet (GrIS). Temporal variations in the BWS mass are defined as the difference between the rate of meltwater runoff within the GrIS and the rate of meltwater discharge into the ocean. We assume that the latter is proportional to the BWS mass itself, which is a commonly-used assumption in hydrology. This results in a simple first-order linear differential equation, the solution to which describes temporal variations in the BWS as a function of time. That function contains a number of parameters to be estimated, including scaling factors to be applied to modelled runoff, as well as the average water storage time. To estimate these parameters, we analyze the vertical component of the bedrock elastic displacements along the Greenland coast using information from GPS data collected by 22 Greenland GNSS Network (GNET) stations. The displacements not related to variations in the BWS are computed and subtracted from the data records using appropriate geophysical models. This concerns, among others, regional climate models (such as RACMO2.3p2), which quantify mass variations associated with the surface mass balance (SMB) and simulate the surface runoff across the GrIS. Our study shows that BWS time in Greenland typically varies between 4.5 weeks at the southeastern (SE) coast to 9 weeks elsewhere. We hypothesize that the shorter water storage time at the SE coast is primarily due to the relatively small width and steep slopes of the ablation zone. Furthermore, we find that the modelled runoff may require an application of scaling factors, which correlate with summer temperatures. The maximum upscaling ? up to 20% ? is required when the summer temperatures are highest. Most likely, this is because regional climate models underestimate water melting or overestimate the fraction of meltwater retained by the firn. In practice, intense meltwater production during a warm summer may increase firn degradation due to pore space filling and formation of impermeable ice layers, which are likely not fully accounted for by current models. Our findings highlight the need for runoff adjustment in regional climate models under warm summer conditions, which are projected for the foreseeable future due to climate warming. This will result in more accurate projections of future GrIS melting and associated global sea level rise. Our results have been recently published in Nature (https://doi.org/10.1038/s41586-024-08096-3).