LONG-TERM CENTRAL COASTAL CALIFORNIA PRECIPITATION VARIABILITY AND RELATIONSHIPS TO EL-NINO-SOUTHERN OSCILLATION

Long precipitation reconstructions (600 years) developed for Santa Bar bara, California, using new big-cone spruce tree-ring chronologies cap ture over 55% of the annual precipitation variance. The modern period of the reconstruction is characterized by low variability and one of t he lowest rates of extreme events within the last 600 years. Precipita tion has reached lower levels in the past than recorded during the mod ern period. The 1987-91 drought ranks as only the tenth worst in the l ast 600 years. Furthermore, although the modem period contains some of the most extreme periods of wetness in the last 600 years, wet years have been relatively infrequent and the mean level of precipitation cl ose to average since the time that most population growth and dam buil ding has occurred in this area. The most unusual feature of the recons truction is increased variability and frequency of wet events during t he late 1500s and early 1600s, which may be related to Little Ice Age climatic changes. An analysis of the relationship between ENSO events and reconstructed precipitation shows no clear, consistent response to ENSO in this area. The probability of a wet year during an ENSO is no greater than during a non-ENSO year. However, when wet years do occur during an ENSO they are often extremely wet.