Influence of convective processes on weather research and forecasting model precipitation biases over East Asia
Influence of convective processes on weather research and forecasting model precipitation biases over East Asia
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DOI：
10.1007/s00382-022-06587-5
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发表时间：
2022-11
期刊：
影响因子：
4.6
通讯作者：
S. Sugimoto;Y. Xue;Tomonori Sato;H. Takahashi
中科院分区：
文献类型：
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作者：
S. Sugimoto;Y. Xue;Tomonori Sato;H. Takahashi
1991 年至 2015 年 5 月至 8 月期间，使用带有 Grell-3D 集合积云参数化的天气研究和预报 (WRF) 模型对东亚进行了 20 公里水平分辨率的动态降尺度，作为初始陆地温度和积雪对次季节到季节预测 (LS4P) 计划的影响的产物。六月份发生强降水时，对陆地上模拟的气候降水偏差进行了调查。模拟低估了梅雨/白乌雨带沿线的降水量，而高估了更北地区的降水量。干偏和湿偏分别扩展到中国长江以南和以北，这标志着降水模拟结果不佳的年份。天气尺度环流模式的模型偏差表明，由于对流活跃，模型中西北太平洋上空的顺时针环流减弱，并抑制了向梅雨/白乌雨带向北的水汽输送。由于华北地区存在明显的反气旋环流偏向，华中地区水汽辐合略有增强。在偏差较大的年份，华南地区出现水汽流入减少和对流不活跃之间的正反馈，而华中地区的水汽输送在区域范围内加剧，导致中国干湿偏差放大。 Kain-Fritch方案用于测试积云参数化的影响，由于对流层低层天气尺度环流模式的修改，改善了华南地区的干燥偏差。但华中地区降水量进一步高估，降水分布精度下降。
Dynamical downscaling with a 20 km horizontal resolution was undertaken over East Asia for the period May–August in 1991–2015 using the Weather Research and Forecasting (WRF) model with Grell-3D ensemble cumulus parameterization as a product of the Impact of Initialized Land Temperature and Snowpack on Sub-Seasonal to Seasonal Prediction (LS4P) program. Simulated climatological precipitation biases were investigated over land during June when heavy precipitation occurred. Simulations underestimated precipitation along the Meiyu/Baiu rainband, while overestimating it farther north. Dry and wet biases expanded to south and north of the Yangtze River in China, respectively, marking years with poor precipitation simulations. Model biases in synoptic-scale circulation patterns indicate a weakened clockwise circulation over the western North Pacific in the model due to active convection there, and suppressed northward moisture transport to the Meiyu/Baiu rainband. Moisture convergence was slightly enhanced over central China due to an apparent anticyclonic circulation bias over northern China. In years with large biases, positive feedback between reduced moisture inflow and inactive convection occurred over southern China, while moisture transport to central China intensified on regional scales, with amplification of dry and wet biases over China. The Kain–Fritch scheme was used to test the influence of cumulus parameterization, improving the dry bias over southern China due to the modification of synoptic-scale circulation patterns in the lower troposphere. However, precipitation was further overestimated over central China, with the accuracy of precipitation distribution deteriorating.