Study On MM5-Variational Assimilation Methods Of Satellite Data And The Application To Meteorological Forecasting

Greater and greater concern and attention in the whole world has focused on using all kinds of non-routinely observed data and data assimilation methods that have developed very quickly in marine atmospheric research, especially in operational forecast. It has become a very urgent problem to use asynoptic data and improve the capability to assimilate data. The research on marine atmospheric numerical forecast and data assimilation methods are very important parts in the project of "marine environmental forecasting and natural disasters reducing technology", which belongs to the national key scientific projects of tenth five-year. The study of the thesis is based on such background to carry out the satellite data assimilation methods connected with MM5 mesoscale meteorology model operational forecast, and to serve for the marine environmental forecast and prediction. It is very clearly that the study of the thesis has important practical value and realistic meaning.A two-dimensional variational (2DVar) data assimilation system connected with MM5 model is set up which based on the augmented Lagrangian algorithm of Sasaki. The Geostationary Meteorological satellite (GMS-5) derived wind data from infrared and water vapor images and TIROS Operational Vertical Sounder (TOYS) temperature and humidity data enter the assimilation system after the quality control of MM5 model. Then, the numerical simulation experiments with satellite assimilation are launched on three typhoons in 2002 using the 2DVar data assimilation system. The comparison analysis with other data assimilation methods, such as Nudging, is also going on the simulation results to typhoon track influence. The assimilation influence on typhoon track with different satellite data is also compared. The results show that the 2DVar assimilation scheme really takes effect and improves the numerical simulation results more or less. The typhoon track errors at model integral 24 hours and 48 hours reduce about 5% and 10.5%, respectively. Though numerical simulation experiments of typhoon processes using 2DVar data assimilation system is not so good as that of the Nudging method. In addition, even using very simple assimilation methods to assimilate satellite data, the positive influence will happen to the simulation results. The 2DVar assimilation scheme used here withsimple theory and numerical stability can be very easily applied to many relevant data assimilation fields.A three-dimensional variation (SDVar) system is successfully combined with MM5, which based on the original version of National numerical prediction center. The present version runs smoothly on a PC with Linux operation system rather than on Delpha workstation and using MICAPS (Meteorological Information Composite Analysis Processing system, by CNMC and CAMPS) T213 data as background. The 3DVar data assimilation system has the ability to assimilate GMS-5 cloud drifted winds and TOYS data. The numerical simulation experiments of typhoon processes are carried out using the 3DVar data assimilation system. After comparing the initial wind, geopential height, relative humidity and the sounding profiles of temperature and humidity at several sounding stations between the original MM5 assimilation scheme and the 3DVar assimilation system, some conclusions are drawn: the relationship among model variables becomes more harmony and more close to observations. The initial field formed by 3DVar system is right and reasonable. The study on the numerical simulation experiments to typhoon processes using 3DVar assimilation system also carries out. The conclusions are drawn after comparing the wind field, geopential height, relative humidity and several sounding profiles at sounding stations between control experiment and 3DVar data assimilation experiments. The results show that the model variables are more harmony in dynamic and physics to the experiments of 3DVAR assimilation. The simulated track errors obviously reduce using the 3DVar assimilation scheme, even to recurvature typhoon.The 2DVar a...