Weakened Yellow Sea Warm Current over the last 2-3 centuries

Variations of oceanic currents beyond the instrumental period are often difficult to characterize, although sea surface temperature (SST) changes along current pathways could provide some indirect information. Here we reconstruct four U-37(Ki)-based annual SST records over the past 2-3 centuries from muddy areas in the Yellow Sea (YS) and the northern East China Sea (ECS) to characterize the regional SST variation patterns and to assess whether such patterns could be used to infer current changes. Three offshore sites are located along the pathway of the Yellow Sea Warm Current (YSWC) and an additional coastal site near the Yangtze River mouth with the minimal YSWC influence. The records show SSTs dropped 3-6 degrees C over the last 2-3 centuries at the three offshore sites, and a warming trend toward the present at the coastal site. The cooling SST trend observed at the three offshore sites is at odds with the average Northern Hemisphere temperature and solar irradiance changes, strongly suggesting that regional processes or drivers in the YS and northern ECS regions overturned the global temperature signal. Accordingly, we propose that the YSWC weakened over the last 2-3 centuries, which might be linked to the East Asian winter monsoon variability. (C) 2013 Elsevier Ltd and INQUA. All rights reserved.