IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing (Jan 2021)

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 P. Dinnat,
  • Jeffrey P. Walker,
  • Nan Ye,
  • Sidharth Misra,
  • Jeffrey R. Piepmeier,
  • Rajat Bindlish,
  • David M. LeVine,
  • Peggy E. OaNeill,
  • Lars Kaleschke,
  • Mark J. Andrews,
  • Caglar Yardim,
  • Mustafa Aksoy,
  • Michael Durand,
  • Chi-Chih Chen,
  • Oguz Demir,
  • Alexandra Bringer,
  • Julie Z. Miller,
  • Shannon T. Brown,
  • Ron Kwok,
  • Tong Lee,
  • Yann Kerr,
  • Dara Entekhabi,
  • Jinzheng Peng,
  • Andreas Colliander,
  • Steven Chan,
  • Joseph A. MacGregor,
  • Brooke Medley,
  • Roger DeRoo,
  • Mark Drinkwater

DOI
https://doi.org/10.1109/JSTARS.2021.3073286
Journal volume & issue
Vol. 14
pp. 4894 – 4914

Abstract

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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 500–1400 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 500–1400 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 500–1400 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.

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