Estimates of meridional overturning circulation variability in the North Atlantic from surface density flux fields
Estimates of meridional overturning circulation variability in the North Atlantic from surface density flux fields
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DOI：
10.1029/2008jc005230
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发表时间：
2009-09-30
影响因子：
3.6
通讯作者：
Marsh, Robert
中科院分区：
文献类型：
--
作者：
Josey, Simon A.;Grist, Jeremy P.;Marsh, Robert
最近由Grist等人开发的一种方法。(2009)用来估计北大西洋不同纬度经向翻转环流强度的可变性。该方法利用Hadley中心耦合模式第3版(HadCM3)和国家环境预报中心(NCEP)/国家大气研究中心(NCAR)再分析观测资料集的表面密度通量场，利用水质量变换理论确定了地面浮力强迫翻转环流(SFOC)。该方法以前的应用是在北纬48度，使用100年的模式输出，这里我们从一个更长的400年数据集中显示，它可以扩展到提供35-65度北纬范围内MOC变化的有用估计。该方法依赖于在需要MOC估计之前的一段时间内SFOC的平均。这个间隔的长度随着纬度从北纬65度时的大约6年到北纬36度时的15年而增加。在北纬60度、北纬48度和北纬36度时，HadCM3 SFOC和MOC时间序列之间的相关系数分别为0.60、0.64和0.39。因此，SFOC方法可能提供关于中高纬度北大西洋MOC可变性的有价值的补充信息，与由北纬26度的Rapid阵列确定的信息相比，它变得不那么有用。然后利用NCEP/NCAR再分析方法对过去50年来北大西洋中高纬度地区的MOC变率进行了估算。
A method developed recently by Grist et al. (2009) is used to obtain estimates of variability in the strength of the meridional overturning circulation (MOC) at various latitudes in the North Atlantic. The method employs water mass transformation theory to determine the surface buoyancy forced overturning circulation (SFOC) using surface density flux fields from both the Hadley Centre Coupled Model version 3 (HadCM3) and National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis observational data set. The previous application of the method was at 48 degrees N using 100 years of model output, and here we show from a longer 400 year data set that it can be extended to provide useful estimates of the MOC variability in the range 35-65 degrees N. The method relies on averaging of the SFOC over an interval prior to that at which the MOC estimate is required. The length of this interval increases as the latitude decreases from about 6 years at 65 degrees N to 15 years at 36 degrees N. Values for the correlation coefficient between the HadCM3 SFOC and MOC time series of 0.60, 0.64, and 0.39 are obtained at 60 degrees N, 48 degrees N, and 36 degrees N. Thus, the SFOC approach may provide valuable complementary information about MOC variability in the middle-high-latitude North Atlantic to that determined from the Rapid array at 26 degrees N but it becomes less useful as latitude decreases. The method is then applied using the NCEP/NCAR reanalysis to estimate MOC variability in the middle-high-latitude North Atlantic for the past 50 years.