An algorithm for estimating downward shortwave radiation from GMS 5 visible imagery and its evaluation over China
An algorithm for estimating downward shortwave radiation from GMS 5 visible imagery and its evaluation over China
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DOI：
10.1029/2009jd013457
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发表时间：
2010-09
影响因子：
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通讯作者：
N. Lu;Ronggao Liu;Jiyuan Liu;S. Liang
中科院分区：
文献类型：
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作者：
N. Lu;Ronggao Liu;Jiyuan Liu;S. Liang
本文提出了一种根据对地静止气象卫星（GMS）5 图像的可见光波段大气层顶部反射率来估算中国上空的向下短波辐射（DSR）的操作方案。该算法通过搜索查找表直接从 GMS 5 图像中检索表面反射率和大气参数，这些查找表由辐射传输模型 SBDART 创建，并考虑了水蒸气吸收和表面高度变化的影响。实验表明，DSR反演对气溶胶类型的选择较敏感，而对云类型的选择较不敏感。明亮表面反射率的不确定性会导致相当大的 DSR 检索误差 (+/-(6-9%))。通过青藏高原的实地测量评估了瞬时反演的DSR，并将每日反演的DSR与中国96个站点一年的地面测量进行了比较。结果表明，估计的 DSR 与地面测量结果吻合良好，相关系数接近 0.9，偏差为 1.5%。全天空条件下每日 DSR 的均方根差异为 17.7%，晴空条件下为 13.1%。这些结果表明，应用于 GMS 5 卫星数据的所提出的方法可以准确估计时间和空间连续的瞬时和每日 DSR。这些 DSR 数据集将具有广泛的应用价值。
This paper presents an operational scheme to estimate downward shortwave radiation (DSR) over China from the visible-band top-of-atmosphere reflectance of the Geostationary Meteorological Satellite (GMS) 5 imagery. The proposed algorithm retrieves surface reflectance and atmospheric parameters directly from GMS 5 images by searching lookup tables, which are created by the radiative transfer model SBDART and consider the effects of water vapor absorption and surface altitude variations. Experiments show that the DSR retrieval is more sensitive to the selection of aerosol type and less to that of the cloud type. Uncertainty in the reflectance of a bright surface leads to a considerable DSR retrieval error (+/-(6-9%)). The instantaneous retrieved DSR is evaluated by field measurements on the Tibetan Plateau, and the daily retrieved DSR is compared with one year's ground-based measurements at 96 stations in China. The results show that the estimated DSR is in good agreement with ground measurements with a correlation coefficient of similar to 0.9 and a bias of 1.5%. Root-mean square differences in the daily DSR are 17.7% for all-sky and 13.1% for clear-sky conditions. These results suggest that the proposed method applied to the GMS 5 satellite data can accurately estimate temporally and spatially continuous instantaneous and daily DSR. These DSR data sets will be useful for a wide range of applications.