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

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 effects in CRTM calculations changes GSI analysis. Compared default aerosol-blind calculations, influences reduced simulated brightness temperature (BT) thermal window channels, particularly over dust-dominant regions. A case study is presented, which illustrates failing correct transmittance leads errors meteorological analyses that assimilate satellite In particular, shows aerosol-affected BTs significantly affects analyzed temperatures lower atmosphere across several regions of globe. Consequently, fully cycled aerosol-aware experiment improves 1–5 d forecasts wind, temperature, geopotential height tropical troposphere Northern Hemisphere stratosphere. Whilst both are well documented with online user guides, tutorials, code repositories, this article intended provide joined-up documentation absorption scattering GSI. It also provides guidance prospective users option radiance assimilation. Scientific aspects BT atmospheric data assimilation briefly discussed.