| Since the beginning of 1998, a new generation of Doppler weather radar net system of our country has been working, researching the form of precipitation, analysis of small and meso scale weather system, warning of severe convective weather, so radar has become an important means of weather system monitoring and forecasting ability, its application has and its significance part in meteotological business and research work.In this paper, from the angle of radar reflectivity factor data, we select Nanjing, Changzhou and Taizhou three radar components in Jiangsu Province to form a small radar network. By selecting the radar synchronous observations volume scan data of three radars in 2013-2014, we compare and analyze the reflectivity difference in the midpoint of two radar couple at all elevation,based on the condition of the analysis of the radar lowest elevation scan stability. The results showed that the average minimum elevation fluctuates between 0.0-0.1° when doing all azimuth scanning. The radar site of Changzhou, it’s lowest elevation do the cycle jitter in the range of -0.0—-0.7 degrees, the average lowest elevation is 0.48 degree; The Nanjing site is on irregular jitter in the range of -0.15—0.08 degrees, the average lowest elevation is 0.43 degree; The Taizhou site is relatively stable, fluctuations in the range of -0.15—0.08 degrees, the average lowest elevation is 0.42 degree, but it has a fluctuation in a fixed azimuth range from 100-150 and 250-300. In general, the difference between highest and lowest elevation was no more than 100m, the effect of the results is negligible. Research on synchronous observation of groundbased radars shows that:each two radar couple has a strong correlation between each other, the average reflectance factor difference of Changzhou is less than Nanjing, and Nanjing is less than Taizhou. When the reflectivity value scale change,the difference of radar reflectivity factor can also be different, the difference in the small values are larger than the bigger value, but the correlation is much better to the former.Different types of rainfall and different elevation differences do have effect to the difference of reflectivity factor, but the total mean trend will never change.As the first and only one active remote sensing of spaceborne radar boarded by the Tropical Rainfall Measuring Mission satellite, PR has been accurate calibration and verification, and it has also being further data calibration and attenuation correction through the WSR-88D radar, so it’s echo intensity data are reliable. Therefore, we choose TRMM PR as a unified reference to do the research on the consistency of comparison of Jiangsu ground-based radar network, in order to test the data stability.Due to the high resolution of space-borne radar in the vertical direction (250m), we pick up vertical profile of reflectivity factor method to do the comparison of space-borne radar and ground-based radar. Results show that:the average profiles trend of radars and the distribution trend of scatter plot can also explain both have good consistency. In terms of the size of reflectivity factor, space-borne radar is lager. In different height layers, reflectance difference is different, at low layer about2-4km,they are similarities, middle layer about 4-6km, PR is lager than GR to3-4dBZ, at high layer 6km,thedifference may reach 5dBZ or more, which means with height increases, the difference betweem Space-borne radar and ground radar increase too.Based on the previous work, we evaluate the fuzzy logic algorithm which extract the radar radial velocity to inverse the dispersion feature and other physical quantities, and use the algorithm to diagnose the rainstorm weather process occurred on July 12,2010 in Jiangsu central area.By extracting from the Doppler radar radial velocity, we get the dispersion feature to compare the results with NCEP data qualitatively and quantitatively, there are differences in position and intensity between convergence and divergence, and found that the radar inversion divergence is 4-5 times bigger than NCEP, but they have good consistency in the divergence field overall trend, and both of their divergence can reflect precipitation dynamic field change during vertical height in the heavy rainstorm course, radar inversion divergence field is about 1-2 hours earlier than rainfall in fact; Correlation evaluation of divergence at different height indicating that the average divergence is credible lower than 400hPa; Evaluation on different rainfall intensity also shows that the extraction method can better characterize the divergence information in precipitation weather process whose rainfall rate is lower than 16mm/h. After this, we analyze the occurrence reason, characteristics of radar image product, dispersion feature from the radar radial velocity, by extracting from the Doppler radar radial velocity, we get the dispersion feature in order to know the rain tendency. In this case, by using the inversed physical quantity parameters of average divergence, vertical velocity and the lightning activity by Ekin index, to diagnose the rainfall and thunderstorms information, the results show that:the average divergence and vertical velocity characteristics calculated by the radar base data changes at different period,and it can reflect the dynamics characteristics of strong rainfall process; the lightning frequency and the rainfall has certain relevance about 1-2h,lightning occurrence time are consistent with the temporal and spatial distribution of radar echo intensity; It is feasible in describing the lightning growth by Ekin, it anticipates 40mins before rain approximately, and it will offer indicative forecast information. |
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