FGOALS-s2 simulation of upper-level jet streams over East Asia: Mean state bias and synoptic-scale transient eddy activity |
| |
| Authors: | SONG Fengfei ZHOU Tianjun |
| |
| Institution: | 1. State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 ;Graduate University of the Chinese Academy of Sciences, Beijing 100049
2. State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 ;Climate Change Research Center, Chinese Academy of Sciences, Beijing 100029 |
| |
| Abstract: | Upper-level jet streams over East Asia simulated by the LASG/IAP coupled climate system model FGOALS-s2 were assessed, and the mean state bias explained in terms of synoptic-scale transient eddy activity (STEA). The results showed that the spatial distribution of the seasonal mean jet stream was reproduced well by the model, except that following a weaker meridional temperature gradient (MTG), the intensity of the jet stream was weaker than in National Centers for Environment Prediction (NCEP)/Department of Energy Atmospheric Model Inter-comparison Project II reanalysis data (NCEP2). Based on daily mean data, the jet core number was counted to identify the geographical border between the East Asian Subtropical Jet (EASJ) and the East Asian Polar-front Jet (EAPJ). The border is located over the Tibetan Plateau according to NCEP2 data, but was not evident in FGOALS-s2 simulations. The seasonal cycles of the jet streams were found to be reasonably reproduced, except that they shifted northward relative to reanalysis data in boreal summer owing to the northward shift of negative MTGs. To identify the reasons for mean state bias, the dynamical and thermal forcings of STEA on mean flow were examined with a focus on boreal winter. The dynamical and thermal forcings were estimated by extended Eliassen-Palm flux (E) and transient heat flux, respectively. The results showed that the failure to reproduce the tripolar-pattern of the divergence of E over the jet regions led to an unsuccessful separation of the EASJ and EAPJ, while dynamical forcing contributed less to the weaker EASJ. In contrast, the weaker transient heat flux partly explained the weaker EASJ over the ocean. |
| |
| Keywords: | FGOALS-s2 jet stream synoptic-scale transient eddy activity meridional temperature gradient extended Eliaseen-Palm flux transient heat flux |
| 本文献已被 CNKI 万方数据 SpringerLink 等数据库收录！ |
| 点击此处可从《大气科学进展》浏览原始摘要信息 |
| 点击此处可从《大气科学进展》下载免费的PDF全文 |
|
