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Diaz, H. F., and C. Fu, 1987: Regional precipitation and temperature variability and its relationship to the Southern Oscillation. In The Climate of China and Global Climate, D. Ye, C. Fu, J. Chao, and M. Yoshino (Eds.), China Ocean Press and Springer-Verlag, 213-223.


The western United States undergoes periods of prolonged dry and wet spells. Climatologically, the region is generally dry, with ample moisture relegated to the higher mountainous areas, where it accumulates in the form of snow during winter and early spring to be made available , as runoff, during late spring and early summer. The Yangtze River Basin of China experiences a dry/wet season regime, with the bulk of the precipitation occurring during the months of May to September (China Monsoon).

We have analyzed variations of seasonal precipitation in the western United States and the Yangtze River Basin (YRB) of China relative to the extreme phases of the Southern Oscillation sea level pressure and precipitation distribution from its High/Dry phase to its Low/Wet one. Using a set of 50 years, 30 Low/Wet events and 20 High/Dry ones, the winter and subsequent spring precipitation patterns in the United States, and summer (May-September) rainfall in YRB were categoried by various means. For China we have made use of the Atlas of Yearly Charts of Dryness/Wetness in China for the last 500-year period. Analogous years were identified and composites of surface wind, sea level pressure, and sea surface temperature in the Pacific for these groups of years were produced.

A similar analysis was performed on winter and spring temperature in the United States based on the same set of Low/Wet, High/Dry ENSO years.