Diurnal Variations of Presummer Rainfall over Southern China
Diurnal Variations of Presummer Rainfall over Southern China
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DOI：
10.1175/jcli-d-15-0666.1
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发表时间：
2017-01-01
影响因子：
4.9
通讯作者：
Qian, Tingting
中科院分区：
文献类型：
--
作者：
Jiang, Zhina;Zhang, Da-Lin;Qian, Tingting
在本研究中，利用合并的0.18分辨率网格小时雨量计和卫星降雨数据集以及国家环境预测中心2008年至2015年4月至6月的最终全球分析来检查中国南方地区夏季前的降雨日周期（DCR）。结果显示，中国南方地区降雨量、频率和强度的日变化显着，从西南到东南部以及季风爆发前到季风爆发后的时期，幅度差异显着。受夜间低层西南风增强影响，西南地区夜间至早晨常出现较大降雨。中国东南部地区以午后降雨为主，这是地表升温的结果，可能是由于当地地形抬升所致。季风爆发前和季风爆发后时期均出现两个日间降雨高峰：一个在清晨，另一个在下午晚些时候。但后者显示出几乎相等幅度的两个峰值，而前者则显示出比下午晚些时候更大的清晨峰值。发现了解释夏季DCR的三种传播模式：（i）东向或东南传播模式主要发生在中国西南部，这与来自热带的暖湿空气输送增强和引起的低层辐合有关；（ii）中国东南部上空的准稳态模式局部出现在弱梯度流的暖区；（iii）内陆传播模式 白天发生与南部沿海地区的海风有关，在季风爆发后期间尤其明显。
In this study, the presummer diurnal cycle of rainfall (DCR) over southern China is examined using the merged 0.18-resolution gridded hourly rain gauge and satellite rainfall dataset and the National Centers for Environmental Prediction Final Global Analysis during April to June of 2008-2015. Results show pronounced diurnal variations in rainfall amount, frequency, and intensity over southern China, with substantially different amplitudes from southwestern to southeastern China, and from the pre- to postmonsoon-onset period. Southwestern China often encounters significant nocturnal-to-morning rainfall under the influence of enhanced nocturnal low-level southwesterly winds. Southeastern China is dominated by afternoon rainfall, as a result of surface heating, likely aided by local topographical lifting. Both the pre- and postmonsoon-onset periods exhibit two diurnal rainfall peaks: one in the early morning and the other in the late afternoon. But the latter shows the two peaks with nearly equal amplitude whereas the former displays a much larger early morning peak than that in the late afternoon. Three propagating modes accounting for the presummer DCR are found: (i) an eastward-or southeastward-propagating mode occurs mostly over southwestern China that is associated with enhanced transport of warm and moist air from tropical origin and the induced low-level convergence, (ii) a quasi-stationary mode over southeastern China appears locally in the warm sector with weak-gradient flows, and (iii) an inland-propagating mode occurs during the daytime in association with sea breezes along the southern coastal regions, especially evident throughout the postmonsoon-onset period.