Process controls and similarity in the us continental-scale hydrological cycle from eof analysis of regional climate model simulations


The surface hydrological output of a regional climate model is investigated with implications for process controls on the spatial-temporal variability of the water cycle over the continental USA. Principal component analysis was performed on the seasonal and annual hydrological cycles to determine their dominant modes of spatial variability. At both seasonal and annual time-scales, the first principal component is dominated by precipitation, which controls seasonal wetness and evaporation and accounts for only 52 to 58% of the variability in the continental-scale hydrological cycle. The second principal component is related to both snowmelt runoff and the time variability of weather (via its influence on the residence time of soil moisture near the land surface) and explains another 22% to 34% of the variability in the hydrological cycle. Based on these findings, a classification of hydroclimatological similarity is proposed in which two areas are similar in their hydroclimatology if their first and second principal components are similar. The classification scheme differs from classical approaches because it is based on dominant modes of variability rather than specific indices such as vegetation or seasonal wetness.


Earth Sciences, Earth Systems Research Center

Publication Date

Spring 1995

Journal Title

Hydrological Processes



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Copyright © 1995 John Wiley & Sons, Ltd