Abstract
Abstract. Arctic Oscillation (AO) and Antarctic Oscillation (AAO) are the leading modes of atmospheric circulation in mid-high latitudes. Previous studies have revealed that the climatic influences of the two modes are dominant in extra-tropical regions. This study finds that AO and AAO signals are also well recorded in coral proxies in the tropical South China Sea. There are significant interannual signals of AO and AAO in the strontium (Sr) content, which represents the sea surface temperature (SST). Among all the seasons, the most significant correlation occurs during winter in both hemispheres: the strongest AO-Sr and AAO-Sr coral correlations occur in January and August, respectively. This study also determined that the Sr content lags behind AO and AAO by 1–3 months. Large-scale anomalies in sea level pressure and horizontal wind at 850 hPa level support the strength of AO/AAO-coral teleconnections. In addition, a comparison with oxygen isotope records from two coral sites in neighboring oceans yields significant AO and AAO signatures with similar time lags. These results help to better understand monsoon climates and their teleconnection to high-latitude climate changes.
Highlights
Arctic Oscillation (AO) and Antarctic Oscillation (AAO) are the leading modes in atmospheric circulation variability in the mid-high latitudes of the Northern and Southern Hemispheres
Significant relations between AAO and δ18O are evident as well. Both the Bali and Bunaken coral proxies show the strongest connection to June AAO, minimums (r=−0.50 and r=−0.38) appear in August and July δ18O at the Bali and Bunaken sites, respectively. These analyses indicate significant associations of δ18O with AO in boreal winters and with AAO in austral winters, again suggesting that AO/AAO has a noticeable influence on precipitation/sea surface temperature (SST) over the South China Sea
Using the climate proxies of Sr and δ18O from three coral sites in the South China Sea, a study was conducted of the statistical relationship between tropical climate proxies and AO/AAO after the possible influence of El Nino/Southern Oscillation (ENSO) was removed, focusing on interannual timescale variations
Summary
During boreal winter and spring, a warmer temperature, smaller weather variances, less frequent cold surges, reduced dust storm frequency, and lighter sea-ice conditions are observed over the East Asian in high-AO years Their relation are connected through atmospheric circulation systems such as the East Asian winter monsoon and Siberian High, and supported by station meteorological data (Gong et al, 2001; Wu and Wang, 2002; Gong and Ho, 2004; Jeong and Ho, 2005), as well as by the climate model simulation (Lu et al, 2007). Preliminary investigations indicated that coral proxies in the South China Sea have a good relation with variations in historical East Asian monsoons (Peng et al, 2003) Considering this information, it would be interesting to determine the relation between AO/AAO and climate proxies in tropical East Asia. This would provide useful information for better understanding climate variations in tropical ocean and East Asia, as well as their possible responses to high-latitude climate changes
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