HR: 1330h
AN: H22B-0917    [PDF]
TI: Variability of United States Runoff and its Climate Teleconnections
AU: * Maurer, E P
EM: emaurer@engr.scu.edu
AF: Santa Clara University, Civil Engineering Department 500 El Camino Real, Santa Clara, CA 95053-0563 United States
AU: Lettenmaier, D P
EM: dennisl@u.washington.edu
AF: University of Washington, Department of Civil and Environmental Engineering Box 352700, Seattle, WA 98195-2700 United States
AU: Mantua, N J
EM: mantua@atmos.washington.edu
AF: Climate Impacts Group, Joint Institute for the Study of the Atmosphere and Ocean University of Washington, Seattle, WA 98195-4235 United States
AB: Understanding the space-time variability of runoff has important implications for climate because of the linkage of runoff and evapotranspiration, as well as practical implications for the prediction of drought and floods. In contrast to climate variables like precipitation and temperature, there has to date been relatively little work evaluating climate teleconnections of runoff, in part because of the absence of data sets that lend themselves to commonly used techniques in climate analysis like principal components analysis (PCA). We examine the space-time variability of runoff over North America between latitudes 25 and 53 degrees north, which is the spatial domain of the North American Land Data Assimilation System (N-LDAS) for which a 50-year retrospective data set of runoff and other land surface water cycle variables has been produced at 1/8 degree latitude-longitude spatial resolution. Past efforts to investigate spatial patterns of runoff variability in the United States have utilized streamflow observations, which have three important drawbacks: first, the location of the observations is highly non-uniform, second, routing effects associated with the conversion of runoff to streamflow confound the interpretation of the observed variables, and third, river impoundments and diversions affect the observations by varying amounts. By using derived spatially distributed runoff which represents natural (no effects of routing, or diversions or impoundments) conditions, we are able to avoid these shortcomings. Using the 50-year 1/8 degree data set, accumulated to monthly amounts, we determine climatic teleconnections using common climate indices (such as Ni¤o3.4 and NAO), by season for lead times of months to a year. High and low values of climatic indices are evaluated separately, which allows independent interpretation of the telconnections of different climatic anomalies to the runoff variability. We identify patterns of runoff variability that are not revealed with observed datasets, especially where observations are sparse. A greater number of significant climate-runoff relationships are exhibited for runoff patterns on the east and west coasts and southern interior, with fewer for Northern interior runoff patterns in the Upper Mississippi and Missouri river regions. Rarely do both the positive and negative phases of any climatic index show significant teleconnection with a particular pattern of runoff variability, lead time and season.
DE: 1833 Hydroclimatology
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2003 Fall Meeting