Three-Dimensional Flow Field Analysis Of Severe Convective And Typhoon Weather Systems In Coastal Areas Of East China

Squall line, hail, typhoon rain are the most common severe convective weather in Coastal areas of East China. Doppler weather radar plays a very important role in the monitoring of these weather systems. Most people still only study with reflectivity, but the radar radial velocity data have not been fully applied in the operational forecast. In order to study the detailed three-dimensional flow field structure of these three kinds of weather systems, this paper has carried out a deep study on the application of radar velocity data and wind retrieval products.Specific content and conclusions are as follows:1) The weather background and the instability energy vertical structure of the squall line occurred on July 27, 2014 in Zhejiang Ningbo is emphatically analyzed using the radar, satellite, and sounding data, revealing the portent information of squall line. For further research on the relationship between the echo structure of the squall line and environment wind vertical shear, comparing and analyzing the vertical structure of the squall line occurred on Mar 19, 2014 in Zhejiang Taizhou with radar vertical cross-sectional structure shows that in Zhejiang area, the spring squall line echo subjects to environment wind direction while that of summer no tilt,and the direction of upper updraft divergence flow after warm air rising is affected by the environment wind in a higher level. The spring environment wind in a high level is always strong, wind vertical shear value is high, warm air flow after rising output in the front of storm, similar to the structure of the mid latitude steering-level squall line type. The summer environment wind is weak, wind vertical shear value is low,the updraft output to the rear of the storm, the structure is similar to the tropical propagating squall line type.Analyzing the convergence center obtained by radial divergence, can predict the location of strong convection more precisely, reveal the evolution of echo.2) Based on the data of three Weather Radars (CINRAD/SA) at Xiamen,Longyan, and Meizhou, the echo evolution, three-dimensional wind structure characteristics and correlative parameters distribution changes of a hail process on the evening of April 8, 2016 in the southern areas of Fujian (Zhangzhou) are examined by means of dual-and triple-Doppler radar retrieval in the kinetic Earth coordinate. The results reveal that: In the primary and developmental stage of the hailstorm system, the horizontal flow field showed cyclonic convergence in low level and the strong upward movement appeared inside clouds. In the mature stage of the hailstorm system, the top of echo was up to 16km high. The reflectivity stronger than 60dBZ developed from the height of 5.3km to 9 km, with the strongest echo reaching 74.5dBZ and there appeared 25km long three-body scatter spike and 32.7km long side-lobe echoes. While the cyclonic circulation existed in low level, anti-cyclone appeared in high level. Strong updrafts, which velocity was larger than 20m/s, lasted for nearly 37 min at the height of 4-8km. The strongest updraft was 51.06m/s at the 7.5km height of super-cell overhang. Downdraft occurred during the period of hail falling. The three-dimensional flow field structure of this hail-failing super-cell shows that the cyclonic airflow in the front of storm ramp up to the top of storm forming anticyclonic circulation, and then gradually forming downward downdraft.Systemic downdraft appeared during weakening period of system, and strong echo reached the ground. Dual-and triple-Doppler radar can retrieve the meticulous structure of super-cell with hail falling reasonably. The results help to understand the structure of hailstorm deeply and improve the forecasting ability of hail.3) Based on four groups of double radars data, winds of the 14th typhoon"Meranti” in 2016 were retrieved by means of dual-and triple-Doppler radar retrieval in the kinetic Earth coordinate. The complete wind of "Meranti" is acquired by trying the networking puzzle technology. We choose the group of the smaller error in overlap area considering the distance d between the inversion point and the radar baseline,the angle a between the inversion point and the radar connection. Analysis of the complete wind field puzzle: The horizontal wind was up to 70.65m/s and the vertical speed was up to 15.7m/s when the typhoon in the strait ocean level. Near the landing time, typhoon was not obviously weakened. The horizontal wind weakened to 50.15m/s and the vertical speed is up to 14.13m/s. At Landing time, the maximum horizontal wind is 50.5m/s and vertical speed is up to 14.6m/s. Typhoon wind field of multiple-Doppler radar retrieval by other detection data validation is credible and with reference significance.