Day 4

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Paper title Mapping Surface and Sub-Surface Ice Sheet Melt Water using Spaceborne Multi-frequency Microwave Radiometry
Authors
  1. Andreas Colliander Jet Propulsion Laboratory, California Institute of Technology Speaker
  2. Mohammad Mousavi Jet Propulsion Laboratory, California Institue of Technology
  3. Shawn Marshall University of Calgary
  4. Samira Samimi University of Calgary
  5. John S. Kimball University of Montana
  6. Julie Z. Miller University of Colorado Boulder
  7. Joel Johnson The Ohio State University
  8. Mariko Burgin Jet Propulsion Laboratory, California Institute of Technology
Form of presentation Poster
Topics
  • A9. Polar Science and Cryosphere
    • A9.04 Mass Balance of the Cryosphere
Abstract text The Greenland and Antarctica ice sheets are major and increasingly important contributors to global sea level rise through the melting of their ice masses. Thus, monitoring and understanding their evolution is more important than ever. However, the understanding of the ice sheet melt is hindered by limitations in current observational melt products. Traditional observational products from satellite microwave sensors report only the top layer surface melt and do not convey information on deeper melt/refreeze processes, due to the relatively high frequency used in the retrievals. The solution is to use multi-frequency observations from L-band (1.4 GHz) to Ka-band (37 GHz) available from spaceborne microwave radiometers which allows for the retrieval of melt water profiles; whereby, the emission at higher frequencies originates from shallow surface layers, while the emission at lower frequencies originates from greater depths and consequently is influenced by seasonal melt water in a thicker surface layer.

We simulated brightness temperatures at 1.4, 6.9, 10, 19 and 37 GHz with the MEMLS (Microwave Emission Model of Layered Snowpacks) emission model with liquid water content (LWC) profiles modeled for the DYE-2 experimental site in Greenland with an energy balance model calibrated with in situ temperature and snow wetness profiles. MEMLS was run using the same snow density and temperature profiles as the energy balance model, but some of the snow structural parameters were adjusted so that the simulated TB values corresponded to the values measured by the SMAP (1.4 GHz) and AMSR2 (6.9, 10, 19 and 37 GHz) microwave radiometers during frozen conditions. Energy balance model predicted LWC and temperature profile time series during the melt season were then used in MEMLS to predict brightness temperature time series over the same period. Simulated and measured brightness temperatures show reasonable agreement, demonstrating that the observations carry information on the melt evolution at different depths. The results also show that TB measurements can be inverted into LWC profiles. The inversion process can be applied to the twice daily continent scale measurements available from satellite instruments to map LWC profiles and track melt evolution in different layers of the ice sheet. We present the most recent results of this analysis and opportunities for continued research and applications. The results are particularly relevant in light of the development of the Copernicus Imaging Microwave Radiometer (CIMR), which will make measurements at these same frequencies.