A High-Precision Sub-Grid Parameterization Scheme for Clear-Sky Direct Solar Radiation in Complex Terrain—Part II: Considering Atmospheric Transparency Differences in Sub-Grid; Pre-Research for Application

Existing sub-grid parameterization schemes for clear-sky direct solar radiation (SPS-CSDSR) assume that the sub-grid cells have the same atmospheric transparency. This study shows that in undulating terrain, significant errors can occur when the sub-grid is in turbid weather or partly above the clou...

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Bibliographic Details
Published inAtmosphere Vol. 15; no. 7; p. 864
Main Authors Li, Changyi, Chen, Bin, Wu, Wei, Chen, Yanan, Feng, Guili, Wen, Xiaopei
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.07.2024
Subjects
Algorithms
Altitude
Atmospheric correction
Atmospheric models
Atmospheric transparency
Clear sky
Climatic analysis
Coupling
Direct solar radiation
Error reduction
fast terrain occlusion algorithm
Flat surfaces
Fog
Interpolation
Occlusion
Parameterization
Radiation
Regional climates
Sky
Solar radiation
sub-grid parameterization
Terrain
terrain cast shadow
Winter solstice
Tien Shan Mountains
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Summary:Existing sub-grid parameterization schemes for clear-sky direct solar radiation (SPS-CSDSR) assume that the sub-grid cells have the same atmospheric transparency. This study shows that in undulating terrain, significant errors can occur when the sub-grid is in turbid weather or partly above the cloud top. A correction factor was proposed. It can effectively eliminate errors under a cloudless sky and can reduce some errors when part of the sub-grid is above the cloud or fog top. For atmospheric models with high horizontal resolution, example test verification shows that the cast shadowless coverage method can lead to large errors. It should no longer be used based on current computing power. These improvements and the high-precision fast terrain occlusion algorithm in Part I will allow SPS-CSDSR to achieve unprecedented high accuracy. Based on the proposed daily interpolation method, the high-precision SPS-CSDSR is also feasible for regional climate simulation. The analysis pointed out that the sub-grid terrain radiative effect (STRE) is distributed over inclined surfaces with larger areas and at different heights. Existing methods of coupling STRE on one flat surface have certain physical drawbacks. This paper suggests introducing parameterization of STRE at different altitudes and improving the coupling of land–air.
ISSN:2073-4433
2073-4433
DOI:10.3390/atmos15070864