20世纪北大西洋温盐环流的年代际变化试评估

Preliminary Evaluation on the Decadal Scale Variability of the North Atlantic Thermohaline Circulation during 20th Century

根据相对丰富的大气器测资料，综合前人对有限的海洋资料的诊断分析，从北大西洋涛动（ＮＡＯ）变率、表层海温（ＳＳＴ）变率、格陵兰海和拉布拉多海的深对流活动长期变化等不同角度，对 ２０世纪大洋温盐环流（Ｔｈｅｒｍｏｈａｌｉｎｅ Ｃｉｒｃｕｌａｔｉｏｎ，ＴＨＣ）变率进行了试评估。结果表明：（１）１９世纪末以来，大西洋温盐环流的变化可分为４个时期：１９００年以前的一段时期，ＴＨＣ较强；１９０４年到１９３０年，ＴＨＣ较弱；１９３１年到１９７２年，ＴＨＣ较强；１９７３年至１９９５年，ＴＨＣ较弱，目前则又有所增强。（２）与ＴＨＣ的变化相联系，大西洋主要气候要素的变化，相互间存在着某种协调关系，ＴＨＣ强，ＮＡＯ弱，北大西洋北部ＳＳＴ升高，格陵兰海的对流活动增强，拉布拉多海的对流活动则减弱。

Based on the linkage between the North Atlantic Oscillation (NAO) and the Atlantic Thermohaline Circulation (THC) revealed by IAP/ LASG GOALS model, and also the instrument-measured climate record, together with systematically integrative analyses on the observed variations of the sea surface temperature, deep convection over the North Atlantic domain, the decadal scale activity of the THC during the twentieth century has been evaluated. The inferred variations of the strength of the THC is that, during two multi-decadal periods of 1870- 1903 and 1931 - 1972, the THC is estimated to have been running stronger, whereas during the two periods 1904- 1930 and 1973- 1994, it appears to have been weaker. The variability of NAO, SST over the northern part of North Atlantic, the long term changes in the convective activity of the North Atlantic, appear to be well-linked on multi-decadal time scales. Evidence of instrument-measured climate record indicates that they change in unison. A robust THC is accompanied with coordinated changes of weaker NAO, higher SST over the northern part of North Atlantic, lower SST in the ocean southeast to the Newfoundland, stronger convection over Greenland Sea and weaker convection in Labrador Sea.