CLIMATE TELECONNECTION BETWEEN TWO SIDES ACROSS THE PACIFIC DURING THE PAST 1000 YEARS

The migration of ITCZ controls monsoonal precipitation over eastern China during the summer and influences the relative position of the polar front related to the Westerlies that dominates precipitation over central California during the winter. Instrumental records of precipitation from Beijing-Tianjin area and central California show many opposite anomalies on decadal time scale during the past 100 years. The opposite anomalies also exist on centennial time scale during the past 1000 years shown by the comparison of the reconstructed climatic records from eastern China and central California. The climatic variability of eastern China has been reconstructed by stable isotope records of a stalagmite collected from Buddha Cave south of Xian. The records show: (1) cool/dry during the first half and cool/wet during the second half of 900–1250 AD; (2) warm and dry during1250–1510 AD; and (3) cold and wet between 1520--1820 AD corresponding to the Little Ice Age. The moisture budget in central California as represented by the geochemical records in core OL-97A retrieved from Owens Lake, California, shows contrasting patterns. The contrasting feature may be explained by average positions of the ITCZ and the polar jet over long periods. When the ITCZ in the western Pacific is strong and its position migrates further north for extended periods than its normal position, the North Pacific Subtropical High advances farther northward, leading to prevailing of the East Asian Monsoon. In the meantime, the position of the polar jet stream may correspondingly shift further north as well. As a result, a wetter-than-normal climate could have prevailed in eastern China and a dryer-than-normal climate could have prevailed in California.