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Abstract. Surface melting on the Antarctic Ice Sheet has been monitored by satellite microwave radiometry for over 40 years. Despite this long perspective, our understanding of the microwave emission from wet snow is still limited, preventing the full exploitation of these observations to study supraglacial hydrology. Using the Snow Microwave Radiative Transfer (SMRT) model, this study investigatesthe sensitivity of microwave brightness temperature to snow liquid water content at frequencies from 1.4 to 37 GHz. We first determine the snowpack properties for eight selected coastal sites byretrieving profiles of density, grain size and ice layers from microwave observations when the snowpack is dry during wintertime. Second, a series of brightness temperature simulations is run with added water. The results show that (i) a small quantity of liquid water (≈0.5 kg m−2) can be detected, but the actual quantity cannot be retrieved out of the full range of possible water quantities; (ii) the detection of a buried wet layer is possible up to a maximum depth of 1 to 6 m depending on the frequency (6–37 GHz) and on the snow properties (grain size, density) at each site; (iii) surface ponds and water-saturated areas may prevent melt detection, but the current coverage of these waterbodies in the large satellite field of view is presently too small in Antarctica to have noticeable effects; and (iv) at 1.4 GHz, while the simulations are less reliable, we found a weaker sensitivity to liquid water and the maximal depth of detection is relatively shallow (<10 m) compared to the typical radiation penetration depth in dry firn (≈1000 m) at this low frequency. These numerical results pave the way for the development of improved multi-frequency algorithms to detect melt intensity and the depth of liquid water below the surface in the Antarctic snowpack.
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Multi-Frequency Passive Remote Sensing of Ice Sheets from L-Band to W-Band
Multi-frequency microwave radiometer measurements can reveal important subsurface characteristics of ice sheets such as internal temperature, density, grain size and ice thickness, which are critical to understand ice sheet dynamics. This study explores the sensitivity of electromagnetic radiation from ice sheets to these properties across the microwave spectrum, from L-band to W-band. The results indicate that (i) the maximum depth for which surface radiations provide information decreases from >2000 m in L-band to ~3 m in W-band, (ii) seasonal variations in internal temperatures are reflected mostly at frequencies in K a -band and above, (iii) impact of the geothermal heat flux can be observed mainly in L- and S-bands, and (iv) changes in density and grain size properties affect the electromagnetic penetration depth, thus, may influence surface emissions across the entire microwave spectrum.
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- Award ID(s):
- 1844793
- PAR ID:
- 10219691
- Date Published:
- Journal Name:
- IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium
- Page Range / eLocation ID:
- 2995 to 2998
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/IGARSS39084.2020.9324374
