南大洋淡水强迫对南半球环状模的影响分析  

Impacts of freshwater forcing over the Southern Ocean on Southern Annular Mode

作　　者：马浩[1] 李正泉[1] 冯涛[1] 刘成彦[2] 

机构地区：[1]浙江省气候中心,浙江杭州310017 [2]南京信息工程大学海洋科学学院,江苏南京210044

出　　处：《气象与环境学报》2015年第3期81-88,共8页Journal of Meteorology and Environment

基　　金：国家自然科学基金项目"中全新世北太平洋年代际振荡及其机制研究"(41106009);国家自然科学基金项目"登陆台风风场三维高分辨率结构模拟与分析研究"(90815028);浙江省气象科技计划项目"热带印度洋海温变异对浙江省短期气候预测的指示意义及应用研究"(2012QN04)共同资助

摘　　要：南半球环状模是南半球热带外大气环流变异的主导模态,对南半球海洋—大气—海冰耦合系统有重要的影响。冰川融化激发的淡水强迫是南大洋的一种重要外强迫。在历史气候记录中,南大洋淡水通量异常曾引发数次全球性气候异常事件。基于海—气完全耦合模式FOAM,在60°S以南的海洋中施加强度为1.0 Sv的理想化淡水通量异常,分析南半球环状模的响应。结果表明:南大洋淡水通量异常可使局地西风增强,且西风的增强在垂向各个层次上均有体现。西风强度的变化导致对流层中大气斜压性增强,平流层中大气斜压性减弱。此外,淡水强迫使环状模的年际变率振幅显著减弱,而年代际变率开始增强,谱能量的变化具有垂向一致性。海温和海冰等外强迫因子的变化对环状模年代际振幅的增强具有重要意义。Southern Annular Mode （SAM）is a dominant mode of the southern extra-tropical circulation,which can exert a strong influence on the ocean-atmosphere-sea ice coupled system in the Southern Ocean （SO）.Fresh-water forcing induced by ice-melting is important for the SO.In historical climate records,SO freshwater flux a-nomaly used to trigger several global climate abnormal events.Based on the ocean-atmosphere fully coupled model FOAM,the response of SAM to idealized freshwater forcing was investigated with 1 .0 Sv freshwater flux anomaly imposed uniformly to the south of 60°S in the SO in order to study the change of SAM induced by the local forc-ing.The results indicate that local westerly wind is significantly strengthened,which can be seen from lower layers to upper layers.Change of westerly wind intensity increases baroclinicity in the troposphere and decreases barocli-nicity in the stratosphere.Moreover,the interannual variability of SAM remarkably weakens,while the interdecadal variability strengthens.Change of spectrum energy is consistent at all vertical layers.Variation of external forcing such as sea surface temperature and sea ice largely contributes to the enhancement of decadal variability of SAM.

关 键 词：南半球环状模 南大洋 淡水强迫 海-气耦合模式 

分 类 号：B467[哲学宗教—外国哲学]