海洋表层温度对台风"蔷薇"路径和强度预测精度的影响

基于中尺度大气模式WRF(Weather Research and Forecasting Model),首先对2007年3次船舶辐射通量观测进行模拟,以检验WRF对长波和短波辐射通量的模拟能力,结果表明使用中国近海海洋环境数值预报系统环流模式POM(Princeton Ocean Model)模拟的高时空分辨率的海洋表层温度能够显著改进短波辐射通量的模拟,而对长波辐射通量模拟的改进不明显。然后,将业务化运行的中国近海海洋环境数值预报系统后报的逐时海洋表面温度(SST)作为WRF底边界条件,对2008年15号强台风"蔷薇"(Jangmi)过程进行了数值后报试验。结果表明,与使用NCEP/NCAR的SST试验后报的台风中心位置偏差相比,使用高时空分辨率的SST能够较为显著地改善"蔷薇"的路径模拟,台风中心位置模拟偏差减少11%,尤其在台风减弱阶段,台风中心位置模拟偏差减少37%。台风强度在台风发展的不同阶段对下垫面SST的变化敏感性不同。台风路径附近的海表面温度下降会导致海洋向大气输送的热量减少从而减弱台风强度。

The impacts of SST on the track and intensity of Typhoon JANGMI, 2008

The Weather Research and Forecasting model (WRF) is employed to test the impacts of sea surface temperature (SST) on the track and intensity of Typhoon Jangmi, 2008 in the region of (15°-41°N, 105°-135°E). Firstly, two scenarios are conducted to test the sensitivities of radiation fluxes to SST. The model-computed radiation fluxes are compared with in-situ data and shows that WRF provides a reasonable prediction only for short-wave radiation fluxes but not for long-wave radiation fluxes in the first scenario. Hourly high resolution SST data from MASNUM wave-tide-circulation coupled system then used as bottom boundary of WRF for the second scenario. The scenario which use SST data from MASNUM system improved the short-wave and long-wave radiation and give a more accurate estimation. Two experiments are also conducted to simulate typhoon JANGMI during September 2008. The high resolution SST data from MASNUM system can improved the typhoon track forecast. The bias of center position of the typhoon reduces about 37% compared with the control experiment. The experiment by using SST from MASNUM model is more realistic than NCEP/NCARG SST from the control run.The results also can show that typhoon intensity has different sensitivity to sea surface temperature in different phase. The SST drop induced by typhoon decrease the heat fluxes transport from ocean to atmosphere and then weaken typhoon.