Diurnal cycle of precipitation over the southeastern Tibetan Plateau and surrounding regions: Insights from intensity–frequency structure
Diurnal cycle of precipitation over the southeastern Tibetan Plateau and surrounding regions: Insights from intensity–frequency structure
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DOI：
10.1002/joc.8029
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发表时间：
2023-02
期刊：
影响因子：
--
通讯作者：
Yin Zhao;Jian Li;Puxi Li
中科院分区：
文献类型：
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作者：
Yin Zhao;Jian Li;Puxi Li
除了降水的频率、强度和日循环各自的重要性外，强度-频率结构的日循环可以揭示更多降水系统演化过程的物理细节。本文提出了一种客观定量描述降水强度-频率结构日循环的方法，并将其应用于青藏高原东南部及其周边复杂地形。结果表明：高海拔地区降水日循环表现为单峰型夜间高峰，低海拔地区降水日循环表现为频率型夜间高峰和强度型下午高峰。与双峰区相比，单峰区弱降水和强降水在夜间都比下午更频繁。进一步分析发现，单峰区和双峰区强频结构的日演化过程不同，反映了降水的不同时空特征和演化过程。在单峰区，东南TP升高区从夜间高峰到下午最小值，弱降水和强降水同步减少；低地形地区总降水减少以强降水减少为主，弱降水同时增加。在双峰区，横断山脉南部强降水对日降水循环的主导作用比云贵高原东南部强降水更为突出。该方法为研究复杂地形下的降水特征提供了一个更详细的物理视角，可进一步用于合理评价和改进数值模型的性能。
Besides the respective importance of the frequency, intensity and diurnal cycle of precipitation, the diurnal cycle of intensity–frequency structure could reveal more physical details about the evolution process of precipitation systems. Here, an objective method to quantitatively depict the diurnal cycle of intensity–frequency structure of precipitation is proposed, and applied to complex terrains of the southeastern Tibetan Plateau (TP) and its surroundings. Results show the diurnal cycle of precipitation over the high terrain has a unimodal night peak, while low terrain with a frequency‐dominated night peak and an intensity‐dominated afternoon peak. Both weak and intense precipitation are more frequent at night than those in the afternoon over unimodal regions compared to bimodal regions. Further analysis reveals different diurnal evolution process of intensity–frequency structure within unimodal and bimodal regions, respectively, which reflects different spatiotemporal traits and evolution process of precipitation. Among unimodal regions, the elevated southeastern TP is featured by the synchronous decrease in both weak and intense precipitation from the night peak to the afternoon minimum. While the decrease of total precipitation in regions with lower terrain is dominated by the decrease of intense precipitation, but with an increase in weak precipitation simultaneously. Regarding bimodal regions, the intense precipitation over southern Hengduan Mountains has a more prominent role in leading the diurnal cycle of precipitation amount, compared with that over the southeastern Yungui Plateau. The proposed method provides a new perspective with more physical details to investigate precipitation characteristics in complex terrains, which could be further used to reasonably evaluate and improve the performance of numerical models.