Preprints
https://doi.org/10.5194/amt-2021-165
https://doi.org/10.5194/amt-2021-165

  05 Jul 2021

05 Jul 2021

Review status: this preprint is currently under review for the journal AMT.

Ground mobile observation system for measuring multisurface microwave emissivity

Wenying He1,2, Hongbin Chen1,2, Yuejian Xuan1, Jun Li1, and Minzheng Duan1,2 Wenying He et al.
  • 1Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
  • 2University of Chinese Academy of Sciences, Beijing 100049, China

Abstract. Large microwave surface emissivities with a highly heterogeneous distribution make it challenging to use satellite microwave data to retrieve precipitation and to be assimilated into numerical models over land. To better understand the microwave emissivity over land surfaces, we designed and established a ground observation system for the in situ observation of microwave emissivities over several typical surfaces. The major components of the system include a dual-frequency polarized ground microwave radiometer, a mobile observation platform, and auxiliary sensors to measure the surface temperature and soil temperature and moisture; moreover, observation fields are designed comprising five different land surfaces.

Based on the observed data from the mobile system, we preliminarily investigated the variations in the surface microwave emissivity over different land surfaces. The results show that the horizontally polarized emissivity is more sensitive to land surfaces than is the vertically polarized emissivity: the former decreases to 0.75 over cement and increases to 0.90 over sand and bare soil and up to 0.97 over grass. The corresponding emissivity polarization difference is obvious over water (> 0.3) and cement (approximately 0.25) but reduces to 0.1 over sand and 0.05 over bare soil and almost 0.01 or close to zero over grass; this trend is similar to that of the Tb polarization difference. At different elevation angles, the horizontally/vertically polarized emissivities over land surfaces obviously increase/slightly decrease with increasing elevation angle but exhibit the opposite trend over water.

Wenying He et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2021-165', Yanqiu Zhu, 25 Jul 2021
    • AC1: 'Reply on RC1', wenying He, 05 Aug 2021
  • RC2: 'Comment on amt-2021-165', Anonymous Referee #2, 28 Jul 2021
    • AC2: 'Reply on RC2', wenying He, 05 Aug 2021
  • RC3: 'Comment on amt-2021-165', Anonymous Referee #3, 01 Aug 2021
    • AC3: 'Reply on RC3', wenying He, 05 Aug 2021

Wenying He et al.

Wenying He et al.

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Short summary
Large microwave surface emissivities (ε) make more diffculties in widely using satellite microwave data over land. Usually ground-based radiometers are fixed to scan field to obtain the temporal evolution of ε over single land-cover area. To obtain the long-term temporal evolution of ε over different land-cover surfaces simultaneously, we devoloped a ground mobile observation system to enhance in situ ε observations, and presented some preliminary results.