混合截断尺度Blending方案及其在西南区域模式中的应用  

Blending Scheme with Mixed Truncation Scale and Its Application in Southwest Regional Model

作　　者：田高山 陈耀登[1] 高庆九[1] 臧增亮 TIAN Gaoshan;CHEN Yaodeng;GAO Qingjiu;ZANG Zengliang(Key Laboratory of Meteorological Disaster of Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science and Technology,Nanjing 210044,Jiangsu,China;College of Meteorology and Oceanography,National University of Defence Technology,Nanjing 211101,Jiangsu,China)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气象灾害预报预警与评估协同创新中心,江苏南京210044 [2]国防科技大学气象海洋学院,江苏南京211101

出　　处：《高原气象》2022年第6期1630-1641,共12页Plateau Meteorology

基　　金：国家自然科学基金项目(42075148);国家重点研发计划重点专项项目(2017YFC1502102)。

摘　　要：西南区域地形复杂多样,产生的灾害性天气系统往往具有多尺度特征,各个尺度的波动信息均影响着天气系统的发生发展。为了在循环同化过程中及时并恰当地引入来自全球模式背景场的信息,修正区域模式对大尺度波段信息的分析和预报偏差,本文以西南区域为研究背景,根据不同类型模式变量的长度尺度特征,将风场的截断尺度与温湿变量的截断尺度进行差异化设置,提出了混合截断尺度的Blending方案,并基于西南区域循环同化系统进行了为期一周的批量循环同化试验和个例结果诊断分析。结果表明,统一和混合截断尺度的Blending方案均能减小循环同化过程中的分析和预报偏差,而混合截断尺度的Blending方案通过对动力场和温湿场采用不同的截断尺度,分别引入更符合动力场和温湿度场尺度特征的全球背景场信息,进一步减小了区域背景场的偏差,提高了循环同化分析的连续性和气象要素预报的准确度。在降水个例分析中,模式在地形陡峭区域出现了明显的降水虚报和落区偏差,混合截断尺度Blending方案能进一步降低大量级降水的虚报率,改进了对降水量级和落区的预报,提高了降水预报准确度。The complex and diverse topography of the southwest region generates disastrous weather systems with multi-scale characteristics,and fluctuation information of each scale affects the occurrence and development of the weather systems. In order to introduce the information from the background field of the global model in a timely and appropriate approach during the update cycle assimilation process,and to correct the bias of the regional model in the analysis and forecasting of large-scale waveform information,this paper takes the southwest region as the research background,setting the truncation scale of wind field and the truncation scale of temperature & humidity variables differently according to the length scale characteristics of different types of model variables. A blending scheme with mixed truncation scale is proposed,and a one-week continuous batch update cycle assimilation experiments and diagnostics of one case are carried out based on the southwest regional update cycle assimilation system. The results show that both the unified and mixed truncation scale blending schemes can reduce the analysis and forecast bias in the process of update cycle assimilation,while the mixed-truncationscale blending scheme can further reduce the bias of regional background field by adopting different truncation scales for the dynamic,temperature,and humidity field,and introduce the global background field information that is more consistent with the scale characteristics of the dynamic,temperature,and humidity field,respectively. The continuous update cycle assimilation analysis and the accuracy of meteorological element forecasting are improved. In the analysis of precipitation case,the model shows significant precipitation misreporting and falling area bias in the steep topography area. The mixed truncation scale blending scheme can further reduce the false report rate of heavy precipitation,improve the forecast skill of precipitation magnitude and falling area,and increase the accuracy of precipitation forecast.

关 键 词：西南区域 循环同化 Blending方案 截断尺度 降水预报 

分 类 号：P456.7[天文地球—大气科学及气象学]