The linkage between meteorology/climate and hydrology of temperate latitude catchments on daily to decade time scales is studied. Detailed hydrology is provided by a hydrologic catchment model, adapted from the operational streamflow forecast model of the National Weather Service River Forecast System. The model is tuned to respond to observed daily precipitation and potential evaporation input. Results from the Bird Creek basin with outlet near Sperry, Oklahoma, and from the Boone River basin with outlet at Webster City, Iowa, indicate that the model quite accurately simulates the observed daily discharge over 40 years at each of the two 2000-km(2) basins. Daily cross-correlations between observed and simulated basin outflows were better than 0.8 for both basins over a 40-year historical period. Soil moisture variability over a period of four decades is studied, and an assessment of temporal and spatial (as related to the separation distance of the two basins) scales present in the estimated soil moisture record is made. Negative soil. water anomalies have larger magnitudes than positive anomalies, and comparison of the simulated soil water records of the two basins indicates spatial scales of variability that in several cases are as long as the interbasin distance. The temporal scales of soil water content are considerably longer than those of the forcing atmospheric variables for all seasons and both basins. Timescales of upper and total soil water content anomalies are typically 1 and 3 months, respectively. Linkage between the hydrologic components and both local and regional-to-hemispheric atmospheric variability is studied, both for atmosphere forcing hydrology and hydrology forcing atmosphere. For both basins, crosscorrelation analysis shows that local precipitation strongly forces soil water in the upper soil layers with a 10-day lag. There is no evidence of soil water feedback to local precipitation. However, significant cross-correlation values are obtained for upper soil water leading daily maximum temperature with 5-10 day lags, especially during periods of extremely high or low soil water content. Complementary results of a spatial hydroclimatic analysis are presented in a companion paper (Cayan and Georgakakos, this issue).
Section / Oceans and Atmosphere Section / Oceans and AtmosphereDivision / Climate, Atmospheric Science and Physical Oceanography