卫星观测台风重力波数值模拟与直接对比验证

Numerical Simulation of Typhoon-generated Gravity Waves Observed by Satellite and its Direct Validation

以ECMWF的T799资料作为WRF-ARW(V3.5)初始场,对卫星高光谱红外大气垂直探测器AIRS观测的2013年超强台风苏力激发平流层重力波过程进行数值模拟,并利用卫星观测对数值模拟结果进行了直接对比验证.数值模拟表明,该台风诱发的重力波在20~40 km高度逆着东风背景流向东向上传播,在水平方向呈半圆弧状;大气的垂直扰动随着高度的增加而增强,在40km高度上达到0.5m·s^(-1).基于三维傅里叶变换的波谱分析表明,平流层重力波水平波长中心值在500 km附近,周期为3~5 h,垂直波长主要为10~26 km.分析表明,在18~40 km高度的净纬向动量通量为6.7×10^(-4)~1.89×10^(-3)Pa,背景流强迫计算值为-0.23~1.21 m·s^(-1)·d^(-1),且在18 km和40 km高度的数值较大.最后,基于辐射传输模式计算的直接对比表明,卫星观测与数值模拟同时揭示了激发的平流层波动可传至40km以上高度及距台风中心2000km以外的区域,且不同资料得到的波动形态、方位以及水平尺度具有较好的一致性.

To analyze the stratospheric gravity waves induced by strong convection, Typhoon Soulik is investigated by the mesoscale model WRF-ARW （3.5 Version）, ECMWF and AIRS observations. The WRF model results show that strong stratospheric gravity waves are induced by Typhoon Soulik, and the background wind plays a great role in modulation of the gravity waves propagation. The wave spectrum analysis reveals that the horizontal wavelength is about 500km, the period is about 3~5h, and the vertical wavelengths are gradually stretched with height about 10~14km, 14~18km and 22~26km in the height of 20km, 30km and 40km. The momentum flux and wave drag are also analyzed. At last, the direct comparison of WRF, ECMWF and AIRS observations based on a radiative transfer model indicates that the stratospheric semicircular arc wave pattern, position and horizontal scale agree well. But there are also some differences among these data. The AIRS can detect more details than WRF and ECMWF data. The order of wave intensity is AIRS, WRF and ECMWF.