A new description of small-scale and large-scale roughness in the fast ocean surface emissivity model

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  • 1 School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Republic of Korea
  • 2 NOAA-CU enter for Environmental Technology, Electrical, Computer, and Energy Engineering, University of Colorado Boulder, Boulder, Colorado 80309, USA
  • 3 National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado 80309, USA
  • 4 The Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China
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Abstract

Widely used FAST Microwave Ocean Surface Emissivity Model (FASTEM) does not include the interaction between small-scale and large-scale roughness, which seems to induce errors in the ocean surface emissivity estimation. In this study, we attempt to develop a new model that might be included in the FASTEM-like model. In the developed model, the large-scale roughness is expressed as a function of the local incidence angle (LIA) within the context of Fresnel reflection theory, incorporating the interactions between the small-scale and large-scale roughness into the fast ocean surface emissivity model, as done in the two-scale approach. With the new expression of the large-scale roughness, we also provide a more physically-based form of the equation for the fast ocean surface emissivity calculation that includes the small-scale scattering over a geometrically rough surface. In addition, an algorithm for estimating two-scale roughness from the measured or modeled polarized emissivities in conjunction with the proposed fast ocean surface emissivity equation is provided. The results demonstrate that the interactions between two-scale roughness should be considered in order to estimate accurate two-scale roughness influences on the ocean surface emissivity.

Denotes content that is immediately available upon publication as open access.

Corresponding author’s address: Dr. Sang-Moo Lee, Center for Environmental Technology, Electrical, Computer, and Energy Engineering, University of Colorado Boulder, Boulder, Colorado, USA. E-mail: dr.sangmoolee@gmail.com; Sang-Moo.Lee@colorado.edu, Phone: +1-720-705-9627

Abstract

Widely used FAST Microwave Ocean Surface Emissivity Model (FASTEM) does not include the interaction between small-scale and large-scale roughness, which seems to induce errors in the ocean surface emissivity estimation. In this study, we attempt to develop a new model that might be included in the FASTEM-like model. In the developed model, the large-scale roughness is expressed as a function of the local incidence angle (LIA) within the context of Fresnel reflection theory, incorporating the interactions between the small-scale and large-scale roughness into the fast ocean surface emissivity model, as done in the two-scale approach. With the new expression of the large-scale roughness, we also provide a more physically-based form of the equation for the fast ocean surface emissivity calculation that includes the small-scale scattering over a geometrically rough surface. In addition, an algorithm for estimating two-scale roughness from the measured or modeled polarized emissivities in conjunction with the proposed fast ocean surface emissivity equation is provided. The results demonstrate that the interactions between two-scale roughness should be considered in order to estimate accurate two-scale roughness influences on the ocean surface emissivity.

Denotes content that is immediately available upon publication as open access.

Corresponding author’s address: Dr. Sang-Moo Lee, Center for Environmental Technology, Electrical, Computer, and Energy Engineering, University of Colorado Boulder, Boulder, Colorado, USA. E-mail: dr.sangmoolee@gmail.com; Sang-Moo.Lee@colorado.edu, Phone: +1-720-705-9627
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