ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Variation Characteristics of Water Vapor Budget and Correlation Analysis with Precipitation in South China During the Recent 40 Years
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Abstract:
South China is an important water vapor transport channel. Studying the water vapor budget in South China is essential for forecasting precipitation processes in South China and its neighboring areas, and comprehending the impact of atmospheric circulation changes on weather and climate in China. Based on ERA5 data, the variation trend of water vapor budget and its relationship with precipitation in South China during the recent 40 years (1983—2022) are analyzed. The results show that water vapor budget in South China mainly inputs from the southern and western boundaries, outputs from the northern and eastern boundaries. The net budget is negative. The water vapor budget shows declining trend, with a significant decrease in output from the eastern boundary. In the four seasons, the input and output significant declines during spring. Water vapor primarily inputs the South China region through the southwest direction of the Indian Ocean—Bay of Bengal and the southeast direction of the Western Pacific. Water vapor in the middle and lower layers (700 hPa) primarily transported from the Indian Ocean—Bay of Bengal, while water vapor in the lower layer (925 hPa) mainly originates from the Western Pacific. In the recent 40 years, water vapor transport in the Indian Ocean—Bay of Bengal and Western Pacific has weakened, and water vapor transport in the direction of northeast to southwest has appeared in South China. Water vapor transport was positively correlated with precipitation in most areas of Guangxi and Guangdong (correlation coefficient >0.6). The strengthening of water vapor transport in southwest China is the key reason of precipitation occurrence. In addition, there is a trend of wetting in the South China region, with a 2.32% increase in precipitation water vapor (PWV) during the recent 40 years, which is related to the decrease trend of total water vapor outflow in the region than that of total inflow. The results of this study can provide a reference for further understanding of water vapor budget changes and abnormal precipitation events in South China.
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