Western U.S. Streamflow and Atmospheric Circulation Patterns during El Niño-Southern Oscillation (ENSO)

Document Type

Article

Publication Date

12-20-1997

Publication Title

Journal of Hydrology

Volume

201

Issue

1-4

First page number:

249

Last page number:

271

Abstract

Using principal component analysis (PCA), cluster analysis, and jackknife analysis, we investigated the spatial and temporal modes that dominate streamflow variability in the western US in response to El Niño-Southern Oscillation (ENSO) events. Spatial variability was investigated with data only from ENSO years and with rotated PCA on 79 streamflow stations in the western United States. Eight regions, or clusters, were thus pinpointed as areas where streamflow tends to co-vary similarly following ENSO events; traditional cluster analysis confirmed the identification of these regions. The ENSO response in streamflow was then further evaluated by forming an aggregate ENSO composite for each region. Temporal variability of western US streamflow in the PCA-identified regions was evaluated with a ‘T-mode’ PCA that isolated the different responses in streamflow following ENSO events. The T-mode PCA breaks the 13 ENSO events that occurred from 1932 to 1993 into five subsets. It is interesting to note that the events in the dominant mode, PC1(+), occurred before 1976, and next mode, PC2(+), included events prior to 1976. Finally, we investigated the atmospheric circulation patterns over the North Pacific Ocean and much of North America that are associated with the various US streamflow responses. The circulation patterns vary according to the prescribed ENSO forcing. The results of this study contribute to a better understanding of the varied ENSO-streamflow relationship in the western US and the use of ENSO for long-range streamflow forecasting.

Keywords

Atmospheric circulation patterns; Cluster analysis; El Niño-Southern Oscillation (ENSO); Jackknife analysis; Principal component analysis (PCA); Streamflow; Western United States

Disciplines

Climate | Environmental Sciences | Fresh Water Studies

Language

English

Permissions

Use Find in Your Library, contact the author, or use interlibrary loan to garner a copy of the article. Publisher copyright policy allows author to archive post-print (author’s final manuscript). When post-print is available or publisher policy changes, the article will be deposited

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