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李丹, 刘玉芝, 邵天彬, 等. 2024. 利用地面观测评估ERA5云底高度产品[J]. 大气科学, 48(2): 735−744. doi: 10.3878/j.issn.1006-9895.2208.22109
引用本文: 李丹, 刘玉芝, 邵天彬, 等. 2024. 利用地面观测评估ERA5云底高度产品[J]. 大气科学, 48(2): 735−744. doi: 10.3878/j.issn.1006-9895.2208.22109
LI Dan, LIU Yuzhi, SHAO Tianbin, et al. 2024. Assessment of the Cloud Base Height Product from ERA5 Reanalysis using Ground-Based Observations [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(2): 735−744. doi: 10.3878/j.issn.1006-9895.2208.22109
Citation: LI Dan, LIU Yuzhi, SHAO Tianbin, et al. 2024. Assessment of the Cloud Base Height Product from ERA5 Reanalysis using Ground-Based Observations [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(2): 735−744. doi: 10.3878/j.issn.1006-9895.2208.22109

利用地面观测评估ERA5云底高度产品

Assessment of the Cloud Base Height Product from ERA5 Reanalysis using Ground-Based Observations

  • 摘要: 云底高度对天气预报和飞行保障有着重要作用,但目前十分缺乏高时空分辨率的云底高度资料。本文利用中国东部地区云底高度的地面观测对ERA5再分析资料的云底高度进行评估,基于地面观测和ERA云底高度的小时平均偏差对ERA进行了初步订正和验证,综合分析了中国地区的云底高度分布特征。分析发现,ERA5再分析数据中的云底高度比观测值整体偏低,其中高估了低云的云底高度,低估了中、高云云底高度,且中、高云云底高度的偏差较大。另外,在有降水的条件下,ERA5数据中低云云底高度的准确性比无降水条件下的相对较高,但中、高云云底高度的准确性却更低。综合地面观测和ERA5数据云底高度的日变化和月变化分析发现,在我国东部地区,白天的云底高度整体低于夜间,峰值出现在夜间22:00(北京时间,下同),谷值出现在上午09:00,秋季和冬季的ERA5云底高度月变化与地面观测资料较为一致。基于日变化分析获得的小时平均偏差对ERA5数据的云底高度进行订正和验证,分析发现,2010~2019年间,中国地区的云底高度呈现自西北向东南逐渐降低的分布特征;中国南部、东北地区和青藏高原区域的云底高度相对较低,其中,青藏高原夏季和秋季的云底高度较低,春季和冬季较高,而沙漠地区在四个季节的云底高度都较高。

     

    Abstract: Cloud base height (CBH) plays an important role in weather forecasting and flight service. However, CBH data with high spatiotemporal resolution are lacking. This study evaluates the CBH product of ERA5 reanalysis data using ground-based observations in eastern China, revealing the CBH feature in China through validated CBH data from ERA reanalysis. Overall, CBHs from ERA5 reanalysis data are lower than those from ground-based measurements, in which low and middle clouds are overestimated and underestimated, respectively. Additionally, under precipitation conditions, CBHs from ERA5 data indicate a higher accuracy for low clouds than for clouds under a non-precipitation synoptic background and middle and high clouds. CBHs are lower in the daytime than at night, peaking at 0900 BJT and 2200 BJT over eastern China in the daytime and at night, respectively. Overall, monthly mean CBHs from ERA5 reanalysis are consistent with the ground-based measurements in autumn and winter. Revised CBHs of ERA5 data gradually decreased from the northwest to the southeast of China in 2010–2019. Furthermore, CBHs are lower over southern China, northeastern China, and the Tibetan Plateau compared to other areas. Over the Tibetan Plateau, CBHs are lower in summer and autumn than in spring and winter. Additionally, the desert region has a higher CBH in all four seasons.

     

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