Summary

The main characteristics of spatial and temporal variability of dryness and wetness during the last 530 years (1470– 1999) are classified over five centuries. They have been investigated by using 100-site dryness=wetness index data that has recorded the historical weather conditions that affect agriculture and living conditions in eastern China. A set of principal modes of spatial variability and time coefficient series describing the dominant temporal vari-ability are extracted by a diagnostic method, the rotated empirical orthogonal function (REOF) analysis. The long-term precipitation around Beijing, north China and the long-term runoffs in the middle Yangtze River are used to confirm the dry=wet variability in north China and the mid-low Yangtze River over the last two centuries. When considering the data from the last 530 years as