Investigation of the Linkages between Oceanic Atmospheric Variability and Continental U.S. Streamflow

Abstract

This study evaluated the long term changes (trend and step) and investigated the possible influences of two indicators of oceanic-atmospheric climate variability, i.e., sea surface temperatures and 500 mbar geopotential height index, on 864 unimpaired water year streamflows in the continental United States. Two nonparametric tests, i.e. Mann-Kendall and Pettitt test, were used to evaluate the changes. Singular value decomposition (SVD) was used to evaluate the association between oceanic-atmospheric indices and streamflow. The change results indicated increasing streamflow patterns in the eastern United States and dominant, decreasing streamflow trends in the Pacific Northwest and South Atlantic Gulf regions with statistically significant step changes occurring during the early 1970s and 1980s. SVD results showed the Pacific SSTs had strong correlations with the Midwest and southern South Atlantic-Gulf and Pacific Northwest regions, whereas the Atlantic SSTs showed strong correlations with New England, South Atlantic-Gulf, and Upper and Lower Colorado regions.