*** 9520484 Wilson This award supports a three year collaboration between Clark Wilson, Geological Sciences Department, University of Texas at Austin, and Li Zhengxin, Shanghai Observatory of the Chinese Academy of Sciences, on optical astromeric observations as measures of global change. The project involves use of optical astromeric observations of latitude to investigate whether such measurements provide useful measures of climate variability. Shanghai Observatory has been designated as the international repository and analysis center for these optical records, and analysis of the data by Professor Li has revealed intriguing fluctuations which appear correlated with recognized climate variations such as the El Nino/Southern Oscillation. The collaboration will combine the unique Shanghai optical astrometry data collection and the experience of Professor Li with the geophysical, computational and climate data resources at the University of Texas at Austin. The objectives of the proposed research are to determine whether there is a physical basis to account for apparent correlations between climate change and optical astromeric data, and to interpret historical optical and climaterelated time series in light of such physical relationships. Although space geodesy has replaced less accurate optical astrometry in monitoring the rotation of the earth, the optical data of the past remain of considerable value. These data are especially useful when combined to form a polar motion time series for the pre-space geodetic period, because it has been shown that polar motion measures global properties of the distribution of air and water over the past century when few climate-related observations are available. ***
