Solar Activity, Ocean/Atmospheric Processes, and Mississippi River Flow
Charles A. Perry [firstname.lastname@example.org], U. S. Geological Survey, Lawrence, Kansas.
The Mississippi River Basin upstream of St. Louis, Missouri, drains approximately 1,805,000 square kilometers of the north-central United States. Total volume of streamflow from the basin is an excellent indicator of climate variability for this region. An examination of monthly streamflow data since 1862 at St. Louis, Missouri, shows a time-lagged relation with solar activity. What appears to be a multi-year lag between solar irradiance and streamflow during the last 50 years may include a multi-decadal lag when the geomagnetic index for solar activity is compared with the entire 143-year streamflow record. Significant correlations (R>0.60) exist between both total solar irradiance and the AA geomagnetic index and the 36-month moving average of streamflow for the Mississippi River at St. Louis. The multi-decadal time lag is similar to the lag (35-year) between tropical Pacific Ocean sea-surface temperatures (SSTs) and the North Atlantic Oscillation reported by Latif (2001). Because the source of moisture for the Mississippi River Basin is the Gulf of Mexico, specific meteorological conditions need to be present before an excess (floods) or shortage (drought) of streamflow occurs. A physical mechanism between solar activity and streamflow is suggested by comparing streamflow with precipitation, surface-layer vorticity, jet-stream vorticity, extratropical SSTs, tropical SSTs, and solar activity. Variations in the correlations among the individual steps indicate that the solar/climate mechanism is complex and has a time element (lag) that may not be constant.Latif, M., 2001, Tropical Pacific/Atlantic Ocean interactions at multi-decadal time scales. Geophys. Res. Let. v.28 n.3 pp. 539-542.