Numerical Simulation Of Indirect Assimilation Of Radar Reflectivity Factor In The Squall Line

In recent years with the development of numerical weather prediction technology, mesoscale numerical prediction model more matureis in many ways, while computer capacity has made the past unimaginable variety of mesoscale, small-scale numerical simulation weather achieved,and mesoscale numerical prediction operations are carried out in many countries.Currently the distance between the sounding station network of 300 km or more, the main representative of the information contained in the synoptic scale and large scale system features. If only conventional sounding data, it will miss a large extent on small scale systems, and satellite images and radar echoes may be part of the application to compensate for this defect, the results show that radar data of the initial field can be optimized more detailed and objective description of the characteristics of rainfall in the scale system significantly improves the model even short-term precipitation, especially off the area and magnitude of precipitation in the forecast accuracy.Based on the radar echo and NCEP reanalysis data of 1°×1°with the 6h interval, a squall line event in the large scale and meso-scale weather background were analyzed comprehensively. In the analysis using the NCEP data and a new generation of radar data, to simulate the process and assimilate the radar reflectivity test, analysis of the evolution of squall line system and the precipitation area, the following conclusions:(1)Radar preprocessing and quality control which include removing anomalous propagation, ground clutter, isolated point, velocity dealiasing, data filling, data smoothing and thinng play an important role in the radar data assimilation.(2) Radar reflectivity factor in the direct assimilation:Radar reflectivity factor of the direct assimilation, the humidity field of adaptation to the thermal field is very obvious; assimilation the higher of radial resolution, the more the radar reflectivity data assimilation,the obvious moisture in changes, the more obvious changes in air pressure caused by the greater, so the wind farm also will be adjusted significantly; radar reflectivity factor of the direct assimilation of the mesoscale heavy rainfall forecast for the improvement is significant.(3) Precipitation in the squall line simulation, we have found in the control experiment the numerical simulation of precipitation are small than the actual rainfall observations, after the assimilation of radar reflectivity data can increase the control of precipitation, under the radar base reflectivity difference between assimilation and distribution of controlled trials can be found, precipitation improved placement and precipitation, precipitation increased 10-30 mm. Show that the radar base reflectivity assimilation of the squall line precipitation forecast is considerably improved.