An Evaluation of Convection‐Permitting Ensemble Simulations of Coastal Nocturnal Rainfall Over South China During the Early‐Summer Rainy Season
An Evaluation of Convection‐Permitting Ensemble Simulations of Coastal Nocturnal Rainfall Over South China During the Early‐Summer Rainy Season
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DOI：
10.1029/2021jd035656
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发表时间：
2022-01
期刊：
影响因子：
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通讯作者：
Ling Huang;Yali Luo;L. Bai
中科院分区：
文献类型：
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作者：
Ling Huang;Yali Luo;L. Bai
对2018年初夏雨季（4 - 6月）华南地区连续进行了对流允许的集合天气研究和预报模拟。这些模拟由8套与行星边界层和地表相关的参数化方案配置。利用密集分布的雨量计和风廓线雷达的观测资料，评价了集合产品在再现华南沿海地区夜间降雨方面的性能。提前12小时的模拟比提前36小时的模拟表现相对较好，但在午夜之后仍然表现出较低的技能。午夜后预报技术的退化与较严重的低空陆上气流和地面气温低估密切相关。来自南海（SCS）的大规模低空陆上气流与陆风/山风相互作用，增强了对流层下层水汽的汇聚和辐合，为沿海山区/城市的降雨产生提供了条件。在较长的提前时间模拟中，低层陆上气流呈现减速趋势，从而间接放大了夜间陆风/山风的影响，导致降雨量的低估更为严重，向南位移误差也比较短的提前时间模拟大。研究结果强调了夜间降雨预报对准确预测南海上游低空陆上气流和被山脉包围的城市地区热状况的依赖性。
Convection‐permitting ensemble Weather Research and Forecasting simulations were successively conducted on each day during the early‐summer rainy season (April‒June) in 2018 over South China. These simulations were configured by eight sets of parameterization schemes associated with the planetary boundary layer and surface layer. The performance of the ensemble products in reproducing the nocturnal rainfall in the coastal region of South China was evaluated using observations from densely distributed rain gauges and wind profiling radars. The simulations at a lead time of 12 hr present a relatively better performance than those at 36 hr lead time, but still exhibit a low skill especially after midnight. The degradation of forecast skill after midnight is closely associated with the worse underestimation of the low‐level onshore flow and land surface air temperature. The large‐scale onshore flow at low levels from the South China Sea (SCS) interacted with land/mountain breezes, enhancing the lower‐troposphere moisture pooling and convergence for the rainfall production over the coastal mountains/cities. In the longer lead‐time simulations, the low‐level onshore flow presented a deceleration tendency and thus indirectly amplified the effects of land/mountain breezes in nighttime, leading to more serious underestimation in rainfall amount and larger southward displacement error than the shorter lead‐time simulation. The findings highlight the dependence of the nocturnal rainfall forecast on accurately predicting the upstream low‐level onshore flow over the SCS and the thermal conditions in the urban region surrounded by mountains.