ATOVS 不同卫星资料在台风模拟中的同化试验研究

利用美国国家大气研究中心(NCAR)开发的中尺度模式WRF(ARW)V3.2 及其三维变分同化系统WRF-3DVAR,以1011 号超强台风“ 凡亚比” 为个例,采用连续循环同化的方法对ATOVS 卫星资料进行同化试验,探讨了同化ATOVS 不同卫星资料对“ 凡亚比” 模拟的影响。结果表明,强度影响方面:同化ATOVS不同资料均可有效改善台风强度,台风中心海平面气压平均偏差从42 hPa 下降到18 hPa,但不同资料间的差异并不显著,平均在6 hPa 以内,这表明仅同化ATOVS 资料对台风强度的改善相对有限。路径影响方面:(1)不同卫星的同一种传感器资料效果略有不同,同化NOAA-18 和NOAA-15 的AMSU-A 资料效果较好,NOAA-16 的AMSU-A 效果较差;同化NOAA-15 和NOAA-16 的AMSU-B 资料效果相当,且均优于AMSU-A 资料。(2) 同一颗卫星不同传感器资料的差异较大,同化AMSU-B 资料的改善较为明显,HIRS-3 次之,AMSU-A较差,而同时同化不同资料并没有带来更为明显的改善。(3) 同时同化多颗卫星ATOVS 资料的试验表明,将多种资料引入到同化系统的同时,也带来相应的累积误差,因而仅同化一颗卫星可能比同时同化两颗或三颗卫星ATOVS 资料的效果要好。 

DATA ASSIMILATION EXPERIMENTS IN TYPHOON NUMERICAL PREDICTION USING DIFFERENT ATOVS RADIANCE

Based on the mesoscale model WRF and its corresponding three-dimensional system WRF-3DVAR,this study adopts a continuous data assimilation method to construct 12 experiments on different ATOVS radiance data,to discuss the impact of different ATOVS radiance data on the intensity and track simulation of the Super typhoon "Fanapi".The results show that on the aspect of intensity,the assimilation of ATOVS radiance data could improve typhoon intensity effectively,the average bias of the central sea level pressure(CSLP) drops to 18hPa,compared to 42hPa of the experiment without data assimilation.However,the difference among the data assimilation experiments are rather indistinctive,less than 6hPa on average,which indicates that the assimilation of ATOVS solely could have relative improvement on typhoon intensity.On the simulation of track,firstly,the data from identical sensors of different NOAA satellites could produce different effect,in terms of the AMSU-A,NOAA-15 and NOAA-18 produce equivalent improvement,whereas NOAA-16 produces slightly worse effect;while the AMSU-A data of NOAA-16 lead to poorest improvement;and for the AMSU-B,NOAA-15 and NOAA-16 produce equivalent and more positive impacts than the AMSU-A.Secondly,assimilation radiance from different sensors of identical satellite could also produce different effects,the AMSU-B produces the largest improvement,the HIRS-3 is inferior to the AMSU-B,whereas the AMSU-A appears to the poorest improvement,moreover,the assimilation of different radiance simultaneously couldn’t produce further improvement.Finally,the experiments of assimilation radiance from multiform satellites simultaneously imply that it may reduce the quality of analysis due to accumulative bias while adding various radiance data into the model,thus the assimilation of ATOVS radiance from single satellite may perform better than two or three satellites.