GRAPES 三维云初始场形成及在短临预报中的应用

摘要

In order to get more accurate cloud initial fields in GRAPES Meso model,the ARPS cloud analysis scheme is introduced.With some modifications or improvements based on the rational law in cloud macro-characteristic and micro-characteristic,the cloud analysis scheme is used to set up a local cloud analysis scheme which suitable for domestic numerical weather prediction model and local synoptic observations. Based on the background field,it integrates data sources from Doppler weather radar three-dimensional mosaic reflectivity data,geostationary meteorological satellite data,and surface observation.The cloud in-itial information is analyzed based on cloud physical laws of thermodynamics and dynamics and the ob-served empirical relationship.After the cloud analysis,analyzed three dimensional fields which include in-formation of cloud hydrometeors are introduced by nudging technique for initialization of GRAPES Meso model.One-month (15 Jul 2014-14 Aug 2014)time serial of experiments in different horizontal resolution (0.03°×0.03°,0.1°×0.1°)are designed to verify the performance of the cloud analysis scheme.Case stud-y shows that cloud macro-characteristic and cloud initial hydrometeors of synoptic system,such as ty-phoon,squall line etc.,could be represented better by using cloud analysis scheme.The satellite cloud simulation technology of university of Wisconsin is adopted to produce the satellite cloud simulation prod-uct,which is convenient to compare the cloud product of model output with FY-2 meteorological satellite cloud products.The comparing result shows that 1 h nowcasting cloud of GRAPES Meso model with cloud information initialized is close to satellite measurment in cloud macro-characteristic and cloud spatial distribution,while the one without cloud information initialized is missing and the brightness temperature is higher than satellite measurment.Until 6 hours,the nowcasting cloud of cloud analysis scheme is more similar to satellite measurment than the one without cloud analysis scheme,and the brightness temperature simulation is reasonable.As for performance of precipitation forecast,it is found that forecast with the cloud analysis has a significant positive impact on short range precipitation forecast.The 1-hour precipitati-on forecast with cloud analysis is closer to observation,and the positive effect can last for over twelve hours,which meets the demand for the short time nowcasting operational system.Furthermore,the spin-up time is also shortened.In long time experiments,the statistical variable of equitable threat score (ETS) of the precipitation forecast is calculated.At the first 6 h forecast in horizontal resolution of both 0.03°× 0.03°and 0.1°×0.1°,the ETS of the precipitation forecast with cloud analysis is obviously increased com-pared with the one without cloud analysis.In the following three 6 h forecast,the positive effects decrease as forecast time increasing.%围绕 GRAPESMeso 的云初始场形成，以 ARPS 模式云分析方案为基础，优化诊断后应用我国风云二号静止气象卫星云产品、多普勒天气雷达三维组网拼图产品等观测资料结合模式背景信息，根据云热力-动力学原理及观测试验经验关系等，对云初始场的信息进行分析并通过松弛逼近同化方法实现对云内微物理信息同化应用。GRAPESMeso 中采用优化后的云初始场方案，水平分辨率为0．03°×0．03°和0．1°×0．1°的1个月（2014年7月15日—8月14日）连续试验和个例分析结果显示：云初始场形成方案能够分析出飑线等天气系统的云系和云内微物理变量特征。从模拟云图看，包含云初始场信息的 GRAPESMeso 的云系的形态特征和分布范围短时临近预报结果更为准确。云初始场信息同化应用后，在1 h 的时间尺度上，即可预报出与实况更为接近的降水；0～12 h 时间范围内对降水均有积极的影响，可满足短时临近预报的需求，降水量级略偏大。批量连续试验（水平分辨率为0．03°×0．03°和0．1°×0．1°）的各个量级降水 ETS（equitable threat score）评分都显著提高。