Skip Navigation Links www.nws.noaa.gov 
NOAA logo - Click to go to the NOAA home page National Weather Service   NWS logo - Click to go to the NWS home page
Climate Prediction Center

 
HOME > Outreach > Meetings > 33rd Annual Climate Diagnostics & Prediction Workshop > Abstracts
 

Simulating Multi-Season Past Droughts
Abstract

 

Abstract Author: Jae-Kyung E. Schemm, K. C. Mo and S.-H. Yoo

Abstract Title: Perpetual Sea Surface Temperature Forcing and Drought over the United States: CLIVAR Drought experiments

Abstract: The CLIVAR drought experiments together with composites based on observed sea surface temperature anomalies (SSTAs) and precipitation (P) data were used to examine the impact of perpetual ENSO and the Atlantic multi decadal oscillation (AMO) on droughts over the United States. The experiments were designed to force an AGCM with prescribed SSTAs for ENSO or the AMO superimposed on the monthly mean SST climatology. The length of runs varies between 35-51 years. There are total four models examined for this study: NCEP/GFS, GFDL, NSIPP and CCM3. P was extracted from the model archive and the 6-month standardized precipitation index (SPI 6) was computed from the P time series. Month under drought was identified when SPI6 is less than -0.8.

The ensemble mean of four models and composites based on observations both show that a cold ENSO is associated with drought over the Southwest, the Colorado basin and the Great Plains. While a cold ENSO winter is conducive to rain over the east coast and the Southeast, a cold ENSO summer has the opposite impact. A perpetual cold ENSO does not create favorable conditions for drought to persist over these areas. From observations, the composites based on the AMO have very weak anomalies because the decadal signals explains very small percentage of variance in comparison to interannual variations. However, the model results indicate that a perpetual warm phase of the AMO does create a favorable condition for drought over the Southwest, the north central United States and wet conditions over Florida.


NOAA/ National Weather Service
NOAA Center for Weather and Climate Prediction
Climate Prediction Center
5830 University Research Court
College Park, Maryland 20740
Page Author: Climate Prediction Center Internet Team
Page last modified: July 14, 2008
Disclaimer
Information Quality
Credits
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities