Preliminary Evaluation on the Decadal Scale Variability of the North Atlantic Thermohaline Circulation during 20th Century
20世纪北大西洋温盐环流的年代际变化试评估

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.