CAM3.0模式中北大西洋风暴轴对“三核型”海温异常的响应

North Atlantic Storm Track Response to “the Triple-Pattern”SST Anomalies in CAM3.0

为了探究冬季（12～2月）北大西洋地区风暴轴与海温异常的关系，利用伴随AO（Arctic Os-cillation）出现的“三核型”海温异常对大气环流模式CAM3．0进行强迫，将模拟结果与NCEP／NCAR再分析资料做对比，发现CAM3．0在该SSTA强迫下可以再现伴随AO异常出现的风暴轴与急流异常，结论可概括为：海温正（负）异常时，北大西洋风暴轴增强（减弱），北美急流出口区向北（向南）摆动；“三核型”海温异常作为外强迫源，可能通过2种途径影响风暴轴的强度：首先通过热力作用改变中纬度低层大气斜压性来直接影响风暴轴，其次通过影响北美急流出口区的南北摆动来间接影响风暴轴；另外，海温正（负）异常可以增强（减弱）瞬变波与基本气流之间的正反馈效应。

It has been well known that“the triple-pattern”interannual SST anomalies in the North Atlantic are principally forced by the dominant modes of Atmosphere variability,the North Atlantic Oscillation（NAO）or Arctic Oscillation（AO）,but to what extent the North Atlantic SST anomalies can affect the Storm Track in the mid-latitudes remains to be an issue. Here we estimate the response of North Atlantic Storm Track to SST anomalies by a GCM named CAM3. 0. The atmospheric CAM3. 0 was forced by the triple SST anom-alies firstly,then the simulation results in winter （December to January）were compared with the NCEP/NCAR reanalysis data. We found the simulation results could reproduce the anomalies of Atlantic Storm Track and Jet accompanying the AO anomalies. Conclu-sions can be summarized as follows：when the SSTA was positive（negative）,the storm track enhanced （weakened）,and the jet exit region had a meridional displacement to polar （equator）. The SSTA may influence the storm track through two ways,one is to change the lower atmospheric baroclinicity to affect the intensity of storm track directly,the other is to influence the meridional displacement of jet firstly,and then the jet influence the storm track. The positive feedback effection between eddies and mean flow becomes severe （weakening）when SSTA is positive （negative）.