Spatial and Temporal Variability of Southern California Precipitation over the Last 400 yr and Relationships to Atmospheric Circulation Patterns

Abstract

Tree-ring chronologies have been used to develop a 400-yr spatial reconstruction of precipitation in coastal and near-interior southern California. This was accomplished by reconstructing the first two precipitation principal components of a 29-station network, which together account for over 83% of the precipitation variance. The first precipitation principal component is representative of a regionwide pattern of above or below normal precipitation and is reconstructed well. Reconstruction of the second precipitation principal component, which represents a north–south contrast in precipitation, is less reliable but still provides useful information. Results show that mean regionwide precipitation during the last 100 yr has been unusually high and less variable compared to other periods in the past. The modern period of the record has also been characterized by a high degree of north–south contrast but not unusually high compared to the record as a whole. Strong contrast during the modern period ... Abstract Tree-ring chronologies have been used to develop a 400-yr spatial reconstruction of precipitation in coastal and near-interior southern California. This was accomplished by reconstructing the first two precipitation principal components of a 29-station network, which together account for over 83% of the precipitation variance. The first precipitation principal component is representative of a regionwide pattern of above or below normal precipitation and is reconstructed well. Reconstruction of the second precipitation principal component, which represents a north–south contrast in precipitation, is less reliable but still provides useful information. Results show that mean regionwide precipitation during the last 100 yr has been unusually high and less variable compared to other periods in the past. The modern period of the record has also been characterized by a high degree of north–south contrast but not unusually high compared to the record as a whole. Strong contrast during the modern period ...