A mechanism for Atlantic multidecadal variability in the Kiel Climate Model
A mechanism for Atlantic multidecadal variability in the Kiel Climate Model
复制标题
DOI：
10.1007/s00382-012-1633-4
复制
发表时间：
2013-10-01
期刊：
影响因子：
4.6
通讯作者：
Ding, Hui
中科院分区：
文献类型：
--
作者：
Ba, Jin;Keenlyside, Noel S.;Ding, Hui
利用大气-海洋-海冰耦合模式--基尔气候模式(KCM)，对大西洋年代际变率(AMV)进行了千年控制模拟。利用三维温盐联合经验正交函数分析，识别出一种周期约为60年、特征与观测相似的振荡模式。该模式解释了北大西洋上层2000米百年和更短时间尺度上30%的变率。它与+/-1-2 Sv的大西洋经向翻转环流(AMOC)和+/-0.2 A C的大西洋海表温度(SST)的变化有关。KCM的AMV是水平和垂直海洋环流之间通过Irminger海对流耦合的异相相互作用的结果。该地区冬季对流主要受亚极环流输送的盐度异常控制。该地区密度水形成的增加(减少)导致15年后AOC较强(弱)，这反过来又导致15年后SPG较弱(较强)。北大西洋次极地盐度变化对AMV的关键作用在长达1000年的模拟中得到证实，盐度恢复到模式气候学：没有模拟对流中的低频变化，也没有60年的变率模式。
Atlantic Multidecadal Variability (AMV) is investigated in a millennial control simulation with the Kiel Climate Model (KCM), a coupled atmosphere-ocean-sea ice model. An oscillatory mode with approximately 60 years period and characteristics similar to observations is identified with the aid of three-dimensional temperature and salinity joint empirical orthogonal function analysis. The mode explains 30 % of variability on centennial and shorter timescales in the upper 2,000 m of the North Atlantic. It is associated with changes in the Atlantic Meridional Overturning Circulation (AMOC) of +/- 1-2 Sv and Atlantic Sea Surface Temperature (SST) of +/- 0.2 A degrees C. AMV in KCM results from an out-of-phase interaction between horizontal and vertical ocean circulation, coupled through Irminger Sea convection. Wintertime convection in this region is mainly controlled by salinity anomalies transported by the Subpolar Gyre (SPG). Increased (decreased) dense water formation in this region leads to a stronger (weaker) AMOC after 15 years, and this in turn leads to a weaker (stronger) SPG after another 15 years. The key role of salinity variations in the subpolar North Atlantic for AMV is confirmed in a 1,000 year long simulation with salinity restored to model climatology: No low frequency variations in convection are simulated, and the 60 year mode of variability is absent.