Peng Yanyu, Liu Yu, Gao Qianqian. 2022. Variation characteristics of clouds and their relationship with precipitation over China in El Niño decaying summers. Acta Meteorologica Sinica, 80(5):701-720. DOI: 10.11676/qxxb2022.049
Citation: Peng Yanyu, Liu Yu, Gao Qianqian. 2022. Variation characteristics of clouds and their relationship with precipitation over China in El Niño decaying summers. Acta Meteorologica Sinica, 80(5):701-720. DOI: 10.11676/qxxb2022.049

Variation characteristics of clouds and their relationship with precipitation over China in El Niño decaying summers

  • Based on various datasets, including observations of ground stations and satellites in China from 1961 to 2010, the variation characteristics of clouds and different types of precipitation over China were analysed in the decaying summers of two types of El Niño events (eastern Pacific El Niño and central Pacific El Niño), and the complex relationship between the variation characteristics of clouds and total precipitation anomalies was discussed. The results demonstrate that the anomalies of total cloud amount and low cloud amount in El Niño decaying summers are about the same as those of precipitation based on station observations. Low cloud forms such as cumulonimbus, nimbostratus, and stratocumulus have become more common. A significant positive correlation exists between cloud amount anomalies and precipitation anomalies over China. At stations where the positive correlation passes the significance test, the linear relationship between cloud amount anomalies and precipitation anomalies is clear and also passes the significance test. In the meantime, the growing ratios of total cloud amount and low cloud amount to precipitation are close to 1:3 and 1:1, respectively. Variations in cloud amounts of high cloud and deep convective cloud, cloud optical thickness and cloud water path are positively correlated with precipitation anomalies based on station records. Convective precipitation anomalies, which account for up to 80% of total precipitation in the regions south of the Yellow River, are the major cause of fluctuation in total precipitation. Low clouds are a good predictor of precipitation in eastern China. The fluctuation of convective precipitation is primarily responsible for the anomalies of total precipitation in southern China in El Niño decaying summers, and the abnormal increases in convective precipitation are directly associated with anomalous increases in deep convective clouds. An El Niño event can boost convective activities in China's monsoon zone in the subsequent summer. Specifically, it leads to increases in deep convective cloud amount and thickness of cloud layer and promotes upward development of cloud top. These effects eventually increase convective precipitation and result in the formation of abnormal rain band.
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