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Tropical cyclone (TC) genesis forecasting is essential for daily operational practices during the typhoon season.The updated version of the Tropical Regional Atmosphere Model for the South China Sea (CMA-TRAMS) offersforecasters reliable numerical weather prediction (NWP) products with improved configurations and fine resolution. Whiletraditional evaluation of typhoon forecasts has focused on track and intensity, the increasing accuracy of TC genesisforecasts calls for more comprehensive evaluation methods to assess the reliability of these predictions. This study aims toevaluate the effectiveness of the CMA-TRAMS for cyclogenesis forecasts over the western North Pacific and South ChinaSea. Based on previous research and typhoon observation data over five years, a set of localized, objective criteria has beenproposed. The analysis results indicate that the CMA-TRAMS demonstrated superiority in cyclogenesis forecasts, pre dicting 6 out of 22 TCs with a forecast lead time of up to 144 h. Additionally, over 80% of the total could be predicted 72 hin advance. The model also showed an average TC genesis position error of 218.3 km, comparable to the track errors ofoperational models according to the annual evaluation. The study also briefly investigated the forecast of Noul (2011). Theforecast field of the CMA-TRAMS depicted thermal and dynamical conditions that could trigger typhoon genesis, con sistent with the analysis field. The 96-hour forecast field of the CMA-TRAMS displayed a relatively organized three dimensional structure of the typhoon. These results can enhance understanding of the mechanism behind typhoon genesis,fine-tune model configurations and dynamical frameworks, and provide reliable forecasts for forecasters. 相似文献
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2016年6月23日14:00—15:00时,江苏省盐城市阜宁县发生了EF-4级有记录以来的强龙卷风过程,造成了当地30 km长,1.7 km宽的严重气象灾害。受局地环境影响,邻近地区在近50年中发生了大于10人次死亡事件的龙卷风11次,其中6次发生于1979年以后。文章首先是:(1)把6次事件日的再分析变量场分解成瞬时气候和扰动两个部分,发现6次事件都与近地面层出现的负高度扰动轴线和扰动冷暖气团的对峙有关,龙卷发生在暖气团一侧;(2)用模式初始场分解的扰动变量和扰动物理量评估欧美模式对产生阜宁龙卷扰动系统的预报能力。后者的结果也发现,当日14时925 hPa高度扰动槽和850 hPa扰动风辐合线作为环境扰动系统,以及湿涡度扰动和湿散度扰动等环境扰动指标量能够突出地表达有利于龙卷风发生的环境条件。欧洲全球模式能够提前42 h稳定预报出后来扰动槽和环境扰动指标量的位置,美国全球模式也可以提前18 h预报出这样的扰动特征。这些扰动变量和扰动指标量能够快速地帮助预报员判断有可能发生强对流天气的大致时空区域和特征。 相似文献
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Previous studies showed that 4 D-Var technique used for data assimilation could be modified for weather control. This study demonstrates the ability of 4 D-Var to influence the future path of a tropical cyclone by calculating perturbations in WRF simulation. Given the background error covariance matrix, the initial field is improved by the vortex dynamic initialization technique. Our results show that 4 D-Var can be applied to control the trajectory of simulated tropical cyclones by producing "optimal" perturbations. In the numerical simulation experiment of Typhoon Mitag in 2019, after this kind of weather control similar to data assimilation, the tropical cyclone moved obviously,and the damaging wind over the coastline weakened. The prediction results after the initial field modified by 4 D-Var have a great change, and the position of the tropical cyclone moved about 0.5° southeastward after assimilation,which misses the southeast coast of China. Moreover, the damaging wind is also weakened. Since the 4 D-Var is premised on the assumption that the model is perfect and does not consider the model error, then the research plan to consider model error and introduce new methods is discussed in the paper. 相似文献
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