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Validation of estimated cloud fraction from MERRA-2 and AIRS data using ground based observation over IAO, Hanle
Advances in Space Research ( IF 2.6 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.asr.2020.05.001
Shantikumar S. Ningombam , Aditya Narendra , B.C. Bhatt , T.P. Prabhu , G.C. Anupama , Dorje Angchuk , Sonam Jorphail

Abstract We report for validation of cloud fraction estimated from high-resolution (hourly) data from MERRA-2 and AIRS instrument aboard NASA’s Aqua satellite during its ascending and descending orbits with hourly ground-based visual observation taken at Indian Astronomical Observatory (IAO), Hanle during 1997-2018. The study reveals 70% useful nights, equivalent to 254 spectroscopic nights in a year. A comparative study of cloud fraction was performed using homogeneous and continuous data spanning six years (2013-2018) from MERRA-2 and AIRS over IAO, Hanle and Merak sites in the Himalayan region, and several astronomical observatories located in Atacama desert in Chile, Canary islands in Spain, National Astronomical Observatory (NAO), Mexico, and Mauna Loa in Hawaii. The study reveals cloud fractions of 0.07-0.11 at 25% (1st Quartile) and 0.32-0.40 at 50% (median) at the Himalayan sites. On the other hand, the median cloud fractions are 0.06-0.13 at the Chilean sites, 0.16 at NAO, and 0.29 at Canary islands. The observed 25% of the cloud fraction at the Himalayan sites during the lowest three cloud-fractional months (October-December) are comparable with other sites located in Chile and Canary islands. The median cloud fraction at Hanle is slightly lower than Mauna Loa. The study further concluded that the percentage of useful nights obtained from the visual observation (70%) at IAO-Hanle is very close to the percentage of clear sky (68%) estimated from the MERRA-2 data.

中文翻译:

使用对 IAO、Hanle 的地面观测验证来自 MERRA-2 和 AIRS 数据的估计云量比例

摘要 我们报告验证了从 MERRA-2 和 NASA Aqua 卫星上的 AIRS 仪器在其上升和下降轨道期间通过在印度天文台 (IAO) 进行的每小时地面目视观测的高分辨率(每小时)数据估计的云分数, 1997-2018 年期间的汉勒。该研究揭示了 70% 有用的夜晚,相当于一年中的 254 个光谱夜晚。使用 MERRA-2 和 AIRS 跨越喜马拉雅地区 IAO、Hanle 和 Merak 站点以及位于智利阿塔卡马沙漠的几个天文台的六年(2013-2018)均匀和连续数据对云量进行了比较研究,西班牙的加那利群岛、墨西哥的国家天文台 (NAO) 和夏威夷的莫纳罗亚 (Mauna Loa)。该研究显示,25%(第一四分位数)和 0.32-0 的云分数为 0.07-0.11。40 在喜马拉雅山的 50%(中位数)。另一方面,智利站点的云分数中值为 0.06-0.13,NAO 为 0.16,加那利群岛为 0.29。在最低的三个云分数月(10 月至 12 月)期间,在喜马拉雅山站点观测到的 25% 的云分数与位于智利和加那利群岛的其他站点相当。Hanle 的平均云量比 Mauna Loa 略低。该研究进一步得出结论,从 IAO-Hanle 的目视观测获得的有用夜晚百分比 (70%) 非常接近根据 MERRA-2 数据估计的晴空百分比 (68%)。在最低的三个云分数月(10 月至 12 月)期间,在喜马拉雅山站点观测到的 25% 的云分数与位于智利和加那利群岛的其他站点相当。Hanle 的平均云量比 Mauna Loa 略低。该研究进一步得出结论,从 IAO-Hanle 的目视观测获得的有用夜晚百分比 (70%) 非常接近根据 MERRA-2 数据估计的晴空百分比 (68%)。在最低的三个云分数月(10 月至 12 月)期间,在喜马拉雅山站点观测到的 25% 的云分数与位于智利和加那利群岛的其他站点相当。Hanle 的平均云量比 Mauna Loa 略低。该研究进一步得出结论,从 IAO-Hanle 的目视观测获得的有用夜晚百分比 (70%) 非常接近根据 MERRA-2 数据估计的晴空百分比 (68%)。
更新日期:2020-08-01
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