Assessing the Assimilation of Himawari-8 observations on Aerosol Forecasts and Radiative Effects During Pollution Transport from South Asia to the Tibetan Plateau
The emissions from South Asia (SA) represent a critical source of aerosols on the Tibetan Plateau (TP), and aerosols can significantly reduce the surface solar energy. To enhance the precision of aerosol forecasting and its radiative effects in SA and TP, we employed a four-dimensional local ensembl...
| Main Authors: | , , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Copernicus Publications
2023
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/egusphere-2023-1581 https://noa.gwlb.de/receive/cop_mods_00068209 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00066642/egusphere-2023-1581.pdf https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1581/egusphere-2023-1581.pdf |
| Summary: | The emissions from South Asia (SA) represent a critical source of aerosols on the Tibetan Plateau (TP), and aerosols can significantly reduce the surface solar energy. To enhance the precision of aerosol forecasting and its radiative effects in SA and TP, we employed a four-dimensional local ensemble transform Kalman filter (4D-LETKF) aerosol data assimilation (DA) system. This system was utilized to assimilate Himawari-8 aerosol optical thickness (AOT) into the Weather Research and Forecasting-Chemistry (WRF-Chem) model to depict one SA air pollution outbreak event in spring 2018. Sensitivity tests for the assimilation system have been conducted firstly to tune temporal localization lengths. Comparisons with independent Moderate Resolution Imaging Spectroradiometer (MODIS) and AErosol RObotic NETwork (AERONET) observations demonstrate that the AOT analysis and forecast fields have more reasonable diurnal variations by assimilating all the observations within 12 h window, which are both better than assimilating the hourly observations in the current assimilation timeslot. Assimilation of the entire window of observations with aerosol radiative effect activation significantly improves the prediction of downward solar radiation compared to the free-run experiment. The assimilation of aerosol radiative effect activation led to a reduction in aerosol concentrations over SA, resulting in increased surface radiation, temperature, boundary layer height, and atmospheric instability. These changes facilitated air uplift, promoting aerosol transport from SA to the southeastern TP and leading to an increase in AOT in this region. |
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