Microwave radiometry at frequencies from 500 to 1400 MHz: an emerging technology for earth observations

Joel T. Johnson, Kenneth C. Jezek, Giovanni Macelloni, Marco Brogioni, Leung Tsang, Emmanuel Dinnat, Jeffrey P. Walker, Nan Ye, Sidharth Misra, Jeffrey R. Piepmeier, Rajat Bindlish, David M. Le Vine, Peggy E. Oneill, Lars Kaleschke, Mark Andrews, Caglar Yardim, Mustafa Aksoy, Michael Durand, Chi Chih Chen, Oguz DemirAlexandra Bringer, Julie Z. Miller, Shannon Brown, Ron Kwok, Tong Lee, Yann H. Kerr, Dara Entekhabi, Jinzheng Peng, Andreas Colliander, Steven K. Chan, Joseph Macgregor, Brooke C. Medley, Roger Dean De Roo, Mark Drinkwater

Research output: Contribution to journalArticleResearchpeer-review


Microwave radiometry has provided valuable spaceborne observations of Earth's geophysical properties for decades. The recent SMOS, Aquarius, and SMAP satellites have demonstrated the value of measurements at 1400 MHz for observing surface soil moisture, sea surface salinity, sea ice thickness, soil freeze/thaw state, and other geophysical variables. However, the information obtained is limited by penetration through the subsurface at 1400 MHz and by a reduced sensitivity to surface salinity in cold or wind-roughened waters. Recent airborne experiments have shown the potential of brightness temperature measurements from 5001400 MHz to address these limitations by enabling sensing of soil moisture and sea ice thickness to greater depths, sensing of temperature deep within ice sheets, improved sensing of sea salinity in cold waters, and enhanced sensitivity to soil moisture under vegetation canopies. However, the absence of significant spectrum reserved for passive microwave measurements in the 5001400 MHz band requires both an opportunistic sensing strategy and systems for reducing the impact of radio-frequency interference. Here we summarize the potential advantages and applications of 5001400 MHz microwave radiometry for Earth observation and review recent experiments and demonstrations of these concepts. We also describe the remaining questions and challenges to be addressed in advancing to future spaceborne operation of this technology along with recommendations for future research activities.

Original languageEnglish
Number of pages20
JournalIEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication statusAccepted/In press - 14 Apr 2021


  • Earth observations
  • Microwave radiometry

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