Abstract
The recently developed gauge-radar-satellite merged hourly precipitation dataset (CMPAS-NRT) offers broad applications in scientific research and operations, such as intelligent grid forecasting, meteorological disaster monitoring and warning, and numerical model testing and evaluation. In this paper, we take a super-long Meiyu precipitation process experienced in the Yangtze River basin in the summer of 2020 as the research object, and evaluate the monitoring capability of the CMPAS-NRT for the process from multiple perspectives, such as error indicators, precipitation characteristics, and daily variability in different rainfall areas, using dense surface rain-gauge observation data as a reference. The results show that the error indicators for CMPAS-NRT are in good agreement with the gauge observations. The CMPAS-NRT can accurately reflect the evolution of precipitation during the whole rainy season, and can accurately capture the spatial distribution of rainbands, but there is an underestimation of extreme precipitation. At the same time, the CMPAS-NRT product features the phenomenon of overestimation of precipitation at the level of light rain. In terms of daily variation of precipitation, the precipitation amount, frequency, and intensity are basically consistent with the observations, except that there is a lag in the peak frequency of precipitation, and the frequency of precipitation at night is less than observed, and the intensity of precipitation is higher than observed. Overall, the CMPAS-NRT product can successfully reflect the precipitation characteristics of this super-heavy Meiyu precipitation event, and has a high potential hydrological utilization value. However, further improvement of the precipitation algorithm is needed to solve the problems of overestimation of light rainfall and underestimation of extreme precipitation in order to provide more accurate hourly precipitation monitoring dataset.
Highlights
Introduction published maps and institutional affilMeiyu is a climatic phenomenon in the middle and lower reaches of the Yangtze River basin in China, Taiwan, south-central Japan, and southern Korea, in which continuous rains occur in June and July, and is a product of the transition from spring to summer in the East Asian atmospheric circulation during the northward advance of the East Asian summer winds, characterized by the appearance of a quasi-stationary cloud band extending from southern Japan to southern China [1,2,3]
The performance of daily variation of precipitation in the CMPAS-NRT product is basically consistent with the observation, with precipitation concentrated in the early morning to morning, except that the frequency of precipitation at night is slightly lower than the observation, and the intensity of precipitation is slightly higher than the observation
The evaluation was carried out on an hour-by-hour precipitation basis, and four sub-regions were delineated according to the differences in total precipitation, with the following main findings: 1
Summary
Meiyu is a climatic phenomenon in the middle and lower reaches of the Yangtze River basin in China, Taiwan, south-central Japan, and southern Korea, in which continuous rains occur in June and July, and is a product of the transition from spring to summer in the East Asian atmospheric circulation during the northward advance of the East Asian summer winds, characterized by the appearance of a quasi-stationary cloud band extending from southern Japan to southern China [1,2,3]. The cloud belts aloft are closely linked to quasi-stationary fronts (i.e., Meiyu fronts) at the surface [4] and are mainly maintained by a combination of warm and humid air masses from the Pacific Ocean and cold air masses from the Arctic. The Meiyu period is one of the three major periods of intense precipitation in the Chinese region, and the duration of the Meiyu period is not long, the intense precipitation caused by the Meiyu front accounts for a significant portion of the total precipitation in central China, in some years even exceeding 50% of the total annual iations.
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