不同热盐环流平均强度下北大西洋气候响应的差异

基于美国大气研究中心的CCSM3（Community Climate System Model version3）模式，对淡水扰动试验中不同热盐环流（thermohline circulation，THC）平均强度下，北大西洋气候响应的差异进行研究。结果表明：1）在不同平均强度下，北大西洋海洋、大气要素的气候态差异显著。相对于高平均强度，在低平均强度下，北大西洋地区海表温度（sea surface temperature，SST）、海表盐度（sea surface salinity，SSS）、海表密度（sea surface density，SSD）、表面气温（surface air temperature）异常减弱，最大负异常位于GIN（Greenland sea--Iceland sea--Norwegiansea）海域；海平面气压（sealev—elpressure，SLP）异常升高，相应于北大西洋海域降温，表现为异常冷性高压的响应特征；海冰分布区域向南扩大；北大西洋西部热带海域降水减少，导致热带辐合带（intertropical convergence zone，ITCZ）南移。2）在不同THC平均强度下，SST、SSS和SSD年际异常最显著的区域不同；在高平均强度下，最显著区域位于GIN海域，而在低平均强度下则位于拉布拉多海海域。3）在高平均强度下，北大西洋SST主导变率模态的变率极大区域位于GIN海，而在低平均强度下该极大区域不存在；北大西洋SLP的主导变率模态表现为类NAO型，但在高平均强度下，类NAO型表现得更明显。

North Atlantic climate response to different average intensity of thermohaline circulation

The CCSM3 （Community Climate System Model version 3 ） developed by US National Cen ter for Atmospheric Research is used to study the characteristics of thermohaline circulation （THC） in the freshwater disturbance experiments with different mean THC intensities, and the influences of THC on the climate in North Atlantic. Results show that： 1 ） In different THC average intensities, the climatol ogy of marine, atmospheric elements over North Atlantic are significantly different. Compared to the high average intensity, in the low average intensity, SST（ sea surface temperature）, SSS （sea surface sa linity）, SSD （ sea surface density ）, SAT （ surface air temperature ） over North Atlantic are weakened, and the largest negative anomaly locates in GIN （Greenland seaIceland seaNorwegian sea）. With the elevation of SLP（ sea level pressure） and the cooling of SST and SAT,there is an abnormal cold high pressure over North Atlantic. Sea ice distribution area expands southward. The precipitation in thewestern tropical Atlantic decreases, leading to ITCZ （intertropical convergence zone） moving south ward. 2） In different THC average intensities, the most notable areas of interannual SST, SSS and SSD anomalies are different. The most significant area locates in GIN in the high average intensity, while in the Labrador waters in the low average intensity. 3 ） In the high average intensity, the maximum of dom inant variability mode of SST over North Atlantic locates in GIN, while it does not exit in GIN in the low average intensity. The dominant variability mode of SLP over North Atlantic is NAOlike mode, but the NAOlike mode is more significant in high average intensity.