A MODEL FOR ANNUAL STREAMFLOW IN THE UPPER MISSISSIPPI BASIN  BASED
ON SOLAR IRRADIANCE

Charles A. Perry.  
U.S. Geological Survey, 4821 Quail Crest Place, Lawrence, KS 66049.

Annual streamflow in the upper Mississippi River basin demonstrates an apparent 
connection to annual solar-irradiance variations.  The relation is associated with the 
amount of solar energy available for absorption by the tropical Pacific Ocean and the 
subsequent effects this stored energy has on mid-latitude atmospheric circulation and 
precipitation occurrence.  The suggested physical mechanism for this relation includes 
varying solar-energy input that creates ocean-temperature anomalies in the tropical 
ocean.  The temperature anomalies are transported northward by ocean currents to 
locations where ocean and atmospheric processes can modify jet-stream patterns. 
These patterns affect jet-stream location and characteristics downwind over North 
America, which affect the occurrence of precipitation and, ultimately, the amount of 
streamflow in the upper Mississippi River basin.  The relation provides an opportunity 
to estimate the annual streamflow of the upper Mississippi River.  A multivariate 
model using solar-irradiance variations and the previous year's basin precipitation 
explains nearly one-half of the annual streamflow variability.  When data for only La 
Nina years are considered, the model explains more than two-thirds of the variability 
since 1950.

Keywords:  annual streamflow, Upper Mississippi basin, solar irradiance
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