Implementation of a Discrete Dipole Approximation Scattering Database Into Community Radiative Transfer Model
Artikel i vetenskaplig tidskrift, 2022

The Community Radiative Transfer Model (CRTM) is a fast model that requires bulk optical properties of hydrometeors in the form of lookup tables to simulate all-sky satellite radiances. Current cloud scattering lookup tables of CRTM were generated using the Mie-Lorenz theory thus assuming spherical shapes for all frozen habits, while actual clouds contain frozen hydrometeors with different shapes. The Discrete Dipole Approximation (DDA) technique is an effective technique for simulating the optical properties of non-spherical hydrometeors in the microwave region. This paper discusses the implementation and validation of a comprehensive DDA cloud scattering database into CRTM for the microwave frequencies. The original DDA database assumes total random orientation in the calculation of single scattering properties. The mass scattering parameters required by CRTM were then computed from single scattering properties and water content dependent particle size distributions. The new lookup tables eliminate the requirement for providing the effective radius as input to CRTM by using the cloud water content for the mass dimension. A collocated dataset of short-term forecasts from Integrated Forecast System of the European Center for Medium-Range Weather Forecasts and satellite microwave data was used for the evaluation of results. The results overall showed that the DDA lookup tables, in comparison with the Mie tables, greatly reduce the differences among simulated and observed values. The Mie lookup tables especially introduce excessive scattering for the channels operating below 90 GHz and low scattering for the channels above 90 GHz.

microwave instruments

cloud scattering

data assimilation

mie scattering

radiative transfer

discrete dipole approximation

Författare

I. Moradi

University of Maryland

National Aeronautics and Space Administration (NASA)

Patrick Stegmann

University Corporation for Atmospheric Research

Benjamin Johnson

University Corporation for Atmospheric Research

Vasileios Barlakas

Chalmers, Rymd-, geo- och miljövetenskap, Geovetenskap och fjärranalys

Patrick Eriksson

Chalmers, Rymd-, geo- och miljövetenskap, Geovetenskap och fjärranalys

Alan J. Geer

European Centre for Medium-Range Weather Forecasts

Ronald Gelaro

National Aeronautics and Space Administration (NASA)

Satya Kalluri

NOAA JPSS Program Office

Daryl Kleist

National Oceanic and Atmospheric Administration

Quanhua Liu

National Oceanic and Atmospheric Administration

Will Mccarty

National Aeronautics and Space Administration (NASA)

Journal of Geophysical Research: Atmospheres

2169897X (ISSN) 21698996 (eISSN)

Vol. 127 24 e2022JD036957

Ämneskategorier

Meteorologi och atmosfärforskning

Annan fysik

Sannolikhetsteori och statistik

DOI

10.1029/2022JD036957

Mer information

Senast uppdaterat

2023-01-10