Fast Radiative Transfer Approximating Ice Hydrometeor Orientation and Its Implication on IWP Retrievals

The accurate simulation of microwave observations clouds and precipitation are computationally challenging. A common simplification is the assumption totally random orientation (TRO); however, studies have revealed that TRO occurs relatively infrequently in reality. more appropriate azimuthally (ARO), but so far it has been a expensive task. Recently fast approximate approach was introduced incorporates hydrometeor into assimilation data from conically scanning instruments. scales extinction vertical (V) horizontal (H) polarised channels to ARO. In this study, application extended basic radiative transfer perspective using Atmospheric Radiative Transfer Simulator high-frequency Global Precipitation Measurement Microwave Imager (GMI). comparison forward simulations GMI showed with selection scaling factors uniform distribution between 1 1.4–1.5, possible mimic full observed polarisation differences at 166 GHz over land water. applicability model 660 also successfully demonstrated by means existing airborne data. As complement, statistical for snow emissivity 160 190 developed. Combining two models made reproduce signals were all surface types, including sea ice. Further, we investigated impact on ice water path (IWP) retrievals. It shown ignoring significant negative (?20% tropics) retrieval accuracy. produced highly realistic IWP distributions. highlight covered regions, which neglected previous studies. These results provide increased confidence performance passive observation mark an essential step towards developing retrievals properties based GMI, Ice Cloud (ICI) other