Radar Data In High Resolution For The Application Of Rapid Cycling Assimilation

Numerical weather forecast technology booming improves the weather forecasting effectively.Especially in the past few decades the continuous improvement of the theory and application technology,the improving of the computer processing capability as well as the high space-time resolution enrichment of observation data and the result of the numerical prediction is becoming more and more accurate.The forecast accuracy improvement must be put in a prominent position,and the major weather disaster early warning is hard core to achieve.Different from the traditional weather forcast,numerical weatherforcast is more accurately,more timely,more detailed,more time and space dimensions change.In numerical weather prediction,the model of integral is nothing but a solving process,the initial and boundary value theory is a unique,and deterministic problem.But observation and data assimilation analysis produced a series of inevitable error,so that we get the initial field have a certain gap with real atmosphere.Because the atmosphere is a highly nonlinear system,numerical model forecast result was highly sensitive to the initial field error,in the mode of time this kind of error increases with time goes long,finally disable forecast results.In order to inhibit the increasing of model prediction error,we need to use data assimilation system continuously introduces atmospheric observation data to the weather model,and then raises the rolling forecast technology and rapid cycling assimilation technology of quick update forecast system is now in concept.This study is different from previous cycle assimilation scheme,adopt the WRF-ARW mode and GSI assimilation system build quick update assimilation system and make analysis and research on forecast results.System use radar radial wind and reflectivity data after the quality control process of data assimilation,and then prediction experiment was carried out,and by using digital filter initialization(DFI)technology to start the model forecast,nearing the forecast times by hours.To improve numerical model for short-term weather forecast effect,multiple loop convection scale rapid cycling assimilation system bring the forecast effect of improvement and data assimilation application problem,by the technique of GSI assimilation and WRF-ARW area model,designed the convection scale rapid cycling assimilation scheme in south China.On April 17-18,2016 in south China the squall line weather strong precipitation process in simulation test,analysis of different cycle assimilation scheme and radar radial wind and reflectivity data assimilation of the radar echo,prediction effect of relative humidity,precipitation,etc,in order to improve the squall line in south China heavy rain process forecast technique.The result is as follows:(1)the 3 dvar assimilation method directly assimilating radar radial wind data ofexperimental results show that although only assimilate the limitations ofconventional data to forecast effect to improve,but many times cycle assimilationfor the model forecast precipitation played a certain role to improve;At the sametime assimilating radar radial wind data with conventional data of humidity andprecipitation simulation techniques are improved,particularly heavy rain abovemagnitude ETS score improvement;Although model simulated rainfall peak isless than actual observations,but assimilating radar radial wind data effectivelyimproved the squall line the strongest period of vertical rise,make strong time andintensity of precipitation is closer to real observation.(2)use in radar reflectivity data cloud analysis,thus indirectly has assimilatedthe radar reflectivity data of the test results show that the radar reflectivityassimilation makes radar reflectivity forecast field events of the hollow tosignificantly reduce the number;Conventional meteorological forecast field in theshort time forecast results show that the radar reflectivity assimilation forecastadvantage,but because of assimilation in the introduction of the new system error,after comprehensive forecast effect decreased;Was strongest period under theradar reflectivity assimilation forecast squall line test in 2 m temperature field,thesurface relative humidity field forecast obvious advantages;Radar reflectivityassimilation forecast effectively reduces the day precipitation forecast in the heavyrain center forecast range is big,increased circulation assimilation technologyeffectively at the same time by hours and observed the correlation between theprecipitation forecast,especially in the forecast period in the late period ofeffective correction of the end of the precipitation forecast in advance.