1. Greenland Ice Sheet Subsurface Temperature Estimation Using Ultrawideband Microwave Radiometry
- Author
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Joel T. Johnson, Alexandra Bringer, Leung Tsang, Shurun Tan, Yuna Duan, Giovanni Macelloni, Michael Durand, Kenneth C. Jezek, Caglar Yardim, Mark Andrews, and Marco Brogioni
- Subjects
Brightness ,Microwave integrated circuits ,Microwave radiometry ,0211 other engineering and technologies ,Borehole ,Greenland ice sheet ,02 engineering and technology ,Physics::Geophysics ,remote sensing ,temperature retrieval ,Temperature sensors ,Electrical and Electronic Engineering ,Physics::Atmospheric and Oceanic Physics ,Microwave measurement ,021101 geological & geomatics engineering ,Remote sensing ,geography ,Temperature measurement ,geography.geographical_feature_category ,Ice ,Microwave radiometer ,Ranging ,Glacier ,Microwave FET integrated circuits ,subsurface temperature ,Brightness temperature ,General Earth and Planetary Sciences ,Ice sheet ,Geology - Abstract
Ice sheet subsurface temperature is important for understanding glacier dynamics, yet existing methods to obtain the temperature of the ice sheet column are limited to in situ sources at present. The ultrawideband software-defined microwave radiometer (UWBRAD) has been developed to investigate the remote sensing of ice sheet internal temperatures. UWBRAD measures brightness temperature spectra from 0.5 to 2 GHz using 12 subchannels and employs a sophisticated algorithm for detection and mitigation of radio frequency interference (RFI). The instrument was deployed during a flight over northwestern Greenland in September 2017 and acquired the first wideband low-frequency brightness temperature spectra over the ice sheet and coastal regions. The results reveal strong spatial and spectral variations that correlate well with internal ice sheet temperature information. In this article, the section of the flight path ranging from the Camp Century to NEEM to NGRIP boreholes is used for subsurface temperature estimation. A ``partially coherent'' forward model is applied along with a Robin model for the temperature profile and a two-scale model of ice sheet density variations to describe measured brightness temperatures. Using this model, vertical temperature profiles are retrieved along the flight path using a sequential Bayesian estimator; borehole measurements at the three campsites are used to obtain Bayesian priors. The retrieved temperature profiles show reasonable behaviors and demonstrate the potential of ultrawideband microwave radiometry for remotely sensing internal ice sheet temperatures.
- Published
- 2022