摘要
利用GAMIL CliPAS"两步法"季度预测试验,检验了后报的1980~1999年北半球夏季西太平洋副热带高压(简称副高)的年际变化,检查了Seoul National University(SNU)动力统计预测系统对SST预测准确度,并讨论了影响中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室格点大气模式(GAMIL)对副高预测效果的可能原因。500hPa位势高度可预报性指数表明西太平洋副高具有较高可预报性。集合平均基本能再现西太平洋副高的变率特征,但最大方差的位置和强度与观测稍有区别。观测证据显示,副高存在2~3年变率和3~5年变率,且2~3年变率比3~5年变率强。GAMIL能够准确预测观测副高的3~5年变率,尽管其强度要强于观测。这与试验所用的预测海温能够很好表现赤道中东太平洋(5.5°S^5.5°N,190.5°E^240.5°E)海温的年际变率有关。同时,GAMIL预测的副高2~3年变率较之观测显著偏弱,这可能与SNU预测的海洋大陆地区(5.5°S^0.5°N,110.5°E^130.5°E)SST的2~3年变率偏弱有关。分析表明,SNU预测海温的这种弱点,与SNU海温统计预测模式所用的历史海温(OISST)本身对海洋大陆地区2~3年变率的刻画能力较弱有关。
The Western Pacific Subtropical High （WPSH） plays an important role in the East Asian climate. The interannual variability of the summer WPSH hindcasted by the GAMIL CliPAS tier-two experiment is investigated. The results show that the Grid Atmospheric Model of State Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences （GAMIL） can reproduce the climatology of the WPSH reasonably. The spatial distribution of predictability index of 500-hPageopotential height shows that the WPSH has high predictability during 1980-1999. The ensemble mean reasonably reproduces the large variability center of the WPSH, although both the position and the strength of the center are slightly different from the NCEP/NCAR reanalysis results. The interannual variability of the WPSH hindeasted by GAMIL is evaluated by defining a WPSH index according to Sui et al. （2007）. The observation evidence shows that the summertime WPSH exhibits significant 2 - 3 years and 3 - 5 years oscillations. The strength of 3 - 5 years oscil- lation is weaker than that of 2 - 3 years oscillation during 1980 - 1999. The GAMIL model captures the 3 - 5 years oscillation well except with strength stronger than that from the reanalysis. The successful reproduction of 3 - 5 years oscillation is attributed to the realistic SST in the equatorial central-eastern Pacific used to drive the model. The SST field predicted by Seoul National University （SNU） SST prediction system can well describe the interannual variability of Nino 3. 4 SST. For the 2 - 3 years oscillation of the WPSH, however, the GAMIL hindcast shows poor skill. Further analysis suggests that it is partly due to the weaker variability of SST field at 2 - 3 years band in the maritime continent （5.5°S - 0. 5°N, 110. 5°E - 130. 5°E）. The quality of predicted SST in the maritime continent partly depends on the quality of historical SST, viz. OISST, which is used in the SNU statistical SST prediction system. The authors suggest that the weaker 2 - 3 years variability of OISST version 2 in the maritime continent should partly account for the model error.
出处
《大气科学》
CSCD
北大核心
2009年第5期959-970,共12页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40523001
40625014
40821092
关键词
季度可预报性
两步法
西太平洋副热带高压
年际变率
seasonal predictability
tier-two
western Pacific subtropical high
interannual variability
