Diagnosis of the Kinetic Energy of the“21·7”Extreme Torrential Rainfall Event in Henan Province,China

An extreme torrential rain(ETR)event occurred in Henan Province,China,during 18-21 July 2021.Based on hourly rain-gauge observations and ERA5 reanalysis data,the ETR was studied from the perspective of kinetic energy(K),which can be divided into rotational wind(V_(R))kinetic energy(K_(R)),divergent wind kinetic energy(K_(D)),and the kinetic energy of the interaction between the divergent and rotational winds(K_(RD)).According to the hourly precipitation intensity variability,the ETR process was divided into an initial stage,a rapid increase stage,and maintenance stage.Results showed that the intensification and maintenance of ETR were closely related to the upper-level K,and most closely related to the upperlevel K_(R),with a correlation coefficient of up to 0.9.In particular,the peak value of hourly rainfall intensity lagged behind the K_(R) by 8 h.Furthermore,diagnosis showed that K transformation from unresolvable to resolvable scales made the ETR increase slowly.The meridional rotational wind(u_(R))and meridional gradient of the geopotential(φ)jointly determined the conversion of available potential energy(APE)to K_(R) through the barotropic process,which dominated the rapid enhancement of K_(R) and then caused the rapid increase in ETR.The transportation of K by rotational wind consumed K_(R),and basically offset the K_(R) produced by the barotropic process,which basically kept K_(R) stable at a high value,thus maintaining the ETR.

Sensitivity Analysis of Ensemble Simulations on a Torrential Rainfall Case over South China Using Multiple PBL and SL Parameterizations

A good representation of the interaction between the planetary boundary layer(PBL)and the surface layer(SL)in numerical models is of great importance for the prediction of the initiation and development of convection.This study examined an ensemble that consists of the available suites of PBL and SL parameterizations based on a torrential rainfall event over south China.The sensitivity of the simulations was investigated against objective measurements using multiple PBL and SL parameterization schemes.The main causes of the bias from different parameterization schemes were further analysed by comparing the good and bad ensemble members.The results showed that good members tended to underestimate the rainfall amount but presented a decent evolution of mesoscale convective systems that were responsible for the torrential rainfall.Using the total energy mass flux(TEMF)scheme,the bad members overestimated the amount and spatial coverage of rainfall.The failure of the bad member was due to a spurious convection initiation(CI)resulting from the overestimated high-θe elevated air.The spurious CI developed and expanded rapidly,causing intensive and extensive rainfall over south China.Consistent with previous studies,the TEMF scheme tends to produce a warmer and moister PBL environment.The detailed sensitivity analysis of this case may provide reference for the operational forecast of rainfall over south China using multiple PBL and SL parameterizations.

Conventional Analysis on a Heavy or Torrential Rain Weather Process

[Objective] The research aimed to analyze a turning weather process in Binzhou City of Shandong Province in midsummer of 2010.[Method] Started from the short-term forecast ideas,the formation reason of heavy or torrential rain and local heavy rainstorm in Binzhou City during 4-5 August,2010 was analyzed from the circulation situation,physical quantity field,radar echo and so on.[Result] The westerly trough and cold air were the trigger mechanisms of precipitation.The warm wet air flow at the edge of subtropical high and the high-altitude low trough were the main systems of precipitation.It was the typical precipitation process that the northwest of subtropical high overlapped with the westerly trough.In the prior period,the high temperature continued.The cold air at 500 hPa made the convection strengthen.It was the main reason that the local precipitation was strong.In the forecast of rainstorm,the specific humidity,K index and SI index were the good physical quantities and reference indexes.In the formation process of rainstorm,K index had the increasing process.When the rainstorm finished,or the rain intensity weakened,K index decreased obviously.SI index indicated the development of convective precipitation.The radar echo analysis found that the mesocyclone appeared in the process for a short time.For it weakened quickly and disappeared in the shift process,the strong precipitation and gale were formed in the west of Binzou,but the hail wasn't generated.[Conclusion] The research provided the experience for the forecast of such weather in future.

Search Methods for Evacuation Routes during Torrential Rain Disasters Using Genetic Algorithms and GIS

The present study aims to propose a method to search for the most appropriate evacuation routes that take calorie consumption required for evacuees to reach evacuation sites into consideration, by focusing on disasters caused by heavy rainfall, and using genetic algorithm (GA) and geographic information system (GIS). Specifically, GA was used to design and develop an evacuation route search algorithm and 4 parameters including the number of generations, mutation rate number of individuals and crossover rate were set by conducting sensitivity analyses. Additionally, GIS was also used to create road network data and contour data for digital maps and calculate the altitude of each crossover point. Based on these, the necessary calorie consumption to reach evacuation sites for each route was calculated, and that made it possible to derive the several evacuation routes with the small values unlike other methods. By using GA and GIS to suggest detailed evacuation routes, which take the necessary calories required to reach evacuation sites into consideration, it can be expected that the present study should contribute to the decision-making of evacuees. Additionally, as the method is based on public information, the method has high spatial and temporal repeatability. Because evacuation routes are proposed based on quantified data, the selected evacuation routes are quantitatively evaluated, and are an effective indicator for deciding on an evacuation route. Additionally, evacuation routes that accurately reflect current conditions can be derived by utilizing detailed information as data.

Study on Torrential Rain Disaster Index and Threshold in Zhangjiajie City

Based on the precipitation data and torrential rain disaster data in Zhangjiajie City of Hunan Province from 2016 to 2020,taking the claim cases of the property and cargo insurance(hereinafter referred to as"property and cargo insurance")from Hunan Branch of the People’s Insurance Company of China as the research sample,the Dominance Analysis Method was used to determine the influence weights of disaster-causing factors to establish a comprehensive disaster-causing index(I)model of torrential rain.Second,an exponential function was used to fit the relationship between the number of town or street which filed claims of property and cargo insurance and I,then to determine the threshold of I corresponding to different accident levels.The claim cases caused by torrential rain disaster in Zhangjiajie in the flood season of 2021 were selected to verify the I and its threshold.The results showed that the number of property and cargo insurance accidents caused by torrential rain in Zhangjiajie was generally low in east and west but high in middle areas.Among the disaster-causing factors,the weight of the 96-h accumulated precipitation on the scope of accident was the largest,reaching 28.6%.The simulated grades of the scope of accident,the amount of claim and the number of accidents of property and cargo insurance had a high correlation with the grades of actual disasters,and all passed the test at the 0.01 significance level.The threshold test results showed that the consistency rate or accuracy between the predicted level and the actual level of torrential rain disaster-causing cases was 71.4%,in which the predicted values of accuracy for the mild,moderate and severe disaster levels were 70%,70%and 100%,respectively.Therefore,the threshold of I established in this study can be used for the industrial meteorological services related to the property and cargo insurance in Zhangjiajie.

A STUDY ON THE PREDICT ABILITY OF GRAPES MODEL OVER SOUTH CHINA: COMPARISONS BY TWO INITIALIZATION CONDITIONS BETWEEN ECMWF AND NCEP

This paper aims to assess the performances of different model initialization conditions(ICs)and lateral boundary conditions between two global models(GMs),i.e.,the European Centre for Medium-Range Weather Forecasts(ECMWF)and National Centers for Environmental Prediction(NCEP),on the accuracy of the Global/Regional Assimilation and Prediction System(GRAPES)forecasts for south China.A total of 3-month simulations during the rainy season were examined and a specific case of torrential rain over Guangdong Province was verified.Both ICs exhibited cold biases over south China,as well as a strong dry bias over the Pearl River Delta(PRD).In particular,the ICs from the ECMWF had a stronger cold bias over the PRD region and a more detailed structure than NCEP.In general,the NCEP provided a realistic surface temperature compared to the ECMWF over south China.Moreover,GRAPES initialized by the NCEP had better simulations of both location and intensity of precipitation than by the ECWMF.The results presented in this paper could be used as a general guideline to the operational numerical weather prediction that uses regional models driven by the GMs.

阜新暴雨日数与太阳黑子活动周期关系研究(英文)

The quasi 11-year cycle of sunspot activities and torrential rain days in Fuxin during 1951-2005 were studied.As was shown in the results,the relative number of sunspots and the torrential rain days in the sunspot cycle of trough value were significantly related with a correlation coefficient of 0.842.At the same time,the correlation coefficient between torrential rain days in Fuxin and the relative number of sunspots of certain year within the sunspot cycle of trough value reached 0.737.It was clear that the torrential rain days in Fuxin were closely related with solar activity.The conclusion would provide the favorable climate background and basis for the study of regularity of rainstorm outbreak,monitoring and forecasting of torrential rain and regularity of agricultural drought and flood.