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https://doi.org/10.5194/gmd-2021-145
https://doi.org/10.5194/gmd-2021-145

Submitted as: model description paper 31 Aug 2021

Submitted as: model description paper | 31 Aug 2021

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

The Aerosol Module in the Community Radiative Transfer Model (v2.2 and v2.3): accounting for aerosol transmittance effects on the radiance observation operator

Cheng-Hsuan Lu1,2, Quanhua Liu3, Shih-Wei Wei1,2, Benjamin T. Johnson4, Cheng Dang1, Patrick G. Stegmann4, Dustin Grogan2, Guoqing Ge5,6, and Ming Hu6 Cheng-Hsuan Lu et al.
  • 1Joint Center for Satellite Data Assimilation, Boulder, CO, USA
  • 2Atmospheric Sciences Research Center, University at Albany, Albany, NY, USA
  • 3Center for Satellite Applications and Research, NOAA/NESDIS, College Park, MD, USA
  • 4Joint Center for Satellite Data Assimilation, College Park, MD, USA
  • 5Cooperative Institute for Research in Environmental Sciences, CU Boulder, CO, USA
  • 6Global System Laboratory, NOAA, Boulder, CO, USA

Abstract. The Community Radiative Transfer Model (CRTM), a sensor-based radiative transfer model, has been used within the Gridpoint Statistical Interpolation (GSI) system for directly assimilating radiances from infrared and microwave sensors. We conducted numerical experiments to illustrate how including aerosol radiative effects in CRTM calculations changes the GSI analysis. Compared to the default aerosol-blind calculations, the aerosol influences reduced simulated brightness temperature (BT) in thermal window channels, particularly over dust-dominant regions. A case study is presented, which illustrates how failing to correct for aerosol transmittance effects leads to errors in meteorological analyses that assimilate radiances from satellite IR sensors. In particular, the case study shows that assimilating aerosol-affected BTs affects analyzed temperatures in the lower atmosphere significantly in several different regions of the globe. Consequently, a fully-cycled aerosol-aware experiment improves 1–5 day forecasts of wind, temperature, and geopotential height in the tropical troposphere and Northern Hemisphere stratosphere. Whilst both GSI and CRTM are well documented with online user guides, tutorials and code repositories, this article is intended to provide a joined-up documentation for aerosol absorption and scattering calculations in the CRTM and GSI. It also provides guidance for prospective users of the CRTM aerosol option and GSI aerosol-aware radiance assimilation. Scientific aspects of aerosol-affected BT in atmospheric data assimilation are briefly discussed.

Cheng-Hsuan Lu et al.

Status: open (until 26 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2021-145', Anonymous Referee #1, 23 Sep 2021 reply
  • RC2: 'Comment on gmd-2021-145', Anonymous Referee #2, 04 Oct 2021 reply
  • CEC1: 'Comment on gmd-2021-145', Juan Antonio Añel, 12 Oct 2021 reply

Cheng-Hsuan Lu et al.

Cheng-Hsuan Lu et al.

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Short summary
This article is a technical note on the aerosol absorption and scattering calculations of the Community Radiative Transfer Model (CRTM) v2.2 and v2.3. It also provides guidance for prospective users of the CRTM aerosol option and Gridpoint Statistical Interpolation (GSI) aerosol-aware radiance assimilation. Scientific aspects of aerosol-affected BT in atmospheric data assimilation are also briefly discussed.