Historic Documentary Evidence for Southern California Precipitation Variability (with Joel Michaelsen, senior author). In Southern California Climate: Trends and Extremes of the Past 2000 Years, Martin Rose and Peter Wigland, editors. Technical Reports, Natural History Museum of Los Angeles County, No. 11, 1999.

Abstarct Preliminary results of a study of using information from historical documentary sources to reconstruct precipitation variability in central and Southern California. A general survey of public source material indicates that there is great deal of information that has never been carefully examined for climatic information. It appears likely that well-documented categorical precipitation reconstructions could be developed for the period 1770-1850. For many years, particularly in the later period, quantitative reconstruction with monthly resolution could be produced. An analysis of Lynch's southern California precipitation reconstruction done in 1931show them to be unsatisfactory in a number of ways. His acceptance of mission crop yield records as accurate proxies for rainfall was unjustified and he did not document his sources and describe his methods in sufficient detail to make his results reproducible. An alternative method for producing detailed reconstructios using daily journals and diary accounts is presented. The results a preliminary trail on the 1840s decade are quite encouraging, suggesting that monthly and seasonal rainfall can be estimated with good accuracy.

Historic document sources have been used to reconstruct climatic records over the last several centuries, often with great success. The climate of northern Europe is known in considerable detail for the last four or five centuries primarily as a result of careful analyses of historic source materials. In this research effort we have made a considerable effort to bring quantitative rigor to the study of historic documentation and climatic reconstruction. The methods and quantitative application are new and will hopefully generate future research in this important research domain. The use of statistic to reconstruct past climatic conditions is central and I try to encourage my student's to become proficient in the use of these analytical methods.