Relationships between Climate Variability, Drought and Model Soil Moisture

C. Tang
T. C. Piechota, University of Nevada Las Vegas

Presented at the American Geophysical Union (AGU) Fall Meeting, December 13-17, 2004, San Francisco, California.

Description

This research investigates the interannual variability of soil moisture as related to large scale climate variability. A three layer hydrological model VIC -3L (Variable Infiltration Capacity Model - 3 layers) was used in the Colorado River Basin and Mississippi River Basin over a 50 year period. The simulation focuses on the soil moisture generation and simulation have been developed between January 1950 and December 2002 at daily time step. Simulation was performed on 1/8 degree resolution for the water balance model of both basins and shows the interannual variability of deep soil moisture. Using wavelet analysis, deep soil moisture is compared to the Palmer Drought Severity Index (PDSI), precipitation, and streamflow to determine whether deep soil moisture is an indicator of climate extremes. Wavelet and coherency analysis for the Colorado River Basin and the upper Mississippi River basin indicate a strong relationship between droughts and the deep soil moisture. Relationships between soil moisture and other large scale climate variability (e.g., ENSO, PDO, sea surface temperatures) are also evaluated.