台风数值模拟中bogus涡旋四维变分同化的研究

Studies on the Four-dimensional Variational Data Assimilation of Bogus Vortex in the Numerical Simulation of Typhoon Phanfone

研究用MM5四维变分同化系统同化bogus涡旋变量对台风数值模拟的影响,对2002年13号台风Phanfone进行48h预报,结果表明:用四维变分方法同化bogus涡旋变量效果优于在背景场中直接植入模型涡旋的传统bogus技术。同时同化bogus涡旋的风、气压、温度和比湿效果不如只同化气压和其中任一变量。同化bogus涡旋的气压和比湿,能够调整模式初始场的其他变量,得到结构更清晰、与环境场更协调的初始涡旋,从而在一定程度上提高了台风Phanfone路径和强度预报的准确性。

The impact of the assimilation of bogus vortex on the typhoon numerical simulation using the MM5 four-dimensional variational data assimilation system is studied in this paper.A series of 48 h simulations are conducted for typhoon Phanfone.The results show that: assimilation of the bogus vortex variables is more effective than the traditional method which implants a synthetic vortex into the background conditions.Simultaneous assimilation of the bogus wind, pressure, temperature and specific humidity data has less positive impact than that of the bogus pressure and any one of other variables.An initial vortex which has a clearer structure and is more consistent with the environment flow is obtained by assimilating the bogus specific humidity and pressure data.