掩星折射率和弯角同化对台风预报影响的对比

为研究无线电掩星探测(GPS RO)弯角和折射率同化对数值预报的影响,以2012年17号台风"杰拉华"为例,利用美国国家环境预报中心(NCEP)的业务同化系统(GSI),以NCEP预报场资料为初始场,分别使用一维弯角观测算子和一维折射率观测算子同化弯角和折射率数据,并与观测数据对比,分析比较了同化掩星弯角和折射率资料对台风路径、强度及大气状态变量的影响。结果表明,在完成掩星弯角和折射率资料同化后,台风路径的预报水平得到明显改进,其中同化弯角资料可以使路径误差减少32%,而同化折射率资料只能减少13%,同化2种掩星资料对台风强度预报也有一定的影响,其中同化弯角资料后在前2天预报的台风中心气压更接近于实际情况,而同化折射率资料对预报有负影响。

Comparison of impact of GPS RO refractivity and bending angle data assimilation for typhoon prediction

The assimilation with GPS RO (global positioning system radio occultation) refractivity and bending angle data was experimented by using NCEP (National Center for Environmental Prediction, US) GSI ( grid point Statistical Interpolation) operational data assimilation system . For the Typhoon Jelawat, No.17 in 2012, its intensity and path were compared through different method. The results show that typhoon path and typhoon intensity prediction are changed by assimilating refractivity and bending angle data. Error of path prediction is reduced by 32% using bending angle data and 13% using refractivity data. The positive impact is achieved when bending angle data is assimilated in the first and second days and negative influences occur using refractivity data.