An Accurate TwoSlab Cloud-Representation Model for Hyperspectral Infrared Radiative Transfer Codes
Abstract
We describe a cloud representation model which converts the N-levelNumerical Weather Prediction cloud level profiles to two randomlyoverlapping slab clouds (typically one for ice and one for waterclouds), for use with both line-by-line as well as fast Radiative TransferAlgorithms (RTA). The radiances computed with this model can be usedfor radiative closure tests and for retrieval purposes. We useatmospheric optical depths from the NASA AIRS Stand Alone RadiativeTransfer Algorithm (SARTA) and a fast Parametrization of Clouds forLongwave Scattering (PCLSAM) algorithm to compute the finaltop-of-atmosphere nadir radiances.Radiative closure is used to benchmark the radiances from the TwoSlabcloud model against those computed using a Maximum Random Overlap(MRO) cloud scheme. Thermodynamic and cloud profiles from the EuropeanCenter for Medium Range Weather Forecasting (ECMWF) model and all-skyinfrared radiances measured by NASA's Atmospheric Infrared Sounder(AIRS) are used for this. Examination of the synthetic spectra fromthe two cloud representation models shows they agree very well witheach other, and also with the AIRS spectra obtained under a variety ofconditions, ranging from no clouds to Deep Convective clouds.The use of the package is demonstrated by using it to retrievegeophysical profiles and cloud information over a region in theTropical West Pacific on a single footprint basis, using ECMWF modelfields as a first guess.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A11P..01D
- Keywords:
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- 0321 Cloud/radiation interaction;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0360 Radiation: transmission and scattering;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSESDE: 3360 Remote sensing;
- ATMOSPHERIC PROCESSES