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Title: THE CURRENT DECADE-SCALE PRECIPITATION FLUCTUATION IN THE SOUTHERN GREAT PLAINS

Author
item Garbrecht, Jurgen
item Rossel, Frederic - Fred

Submitted to: American Meteorological Society
Publication Type: Proceedings
Publication Acceptance Date: 1/1/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Variations in mean annual precipitation go through cycles that can exceed 10 years in duration. Such variations in precipitation touch many aspects of our society that depend on weather and water, such as agriculture, transportation and energy production, as well as drought and flood preparedness. One such cycle in precipitation happened during the dust bowl years and had profound human, agricultural and societal consequences. This study investigates the characteristics of the latest variation in mean annual precipitation in the Southern Great Plains. The geographic extent of the study includes the states of Colorado, Nebraska, Kansas, Missouri, New Mexico, Oklahoma, Arkansas, Texas and Louisiana. The results show that mean annual precipitation has increased in the last two decades over a large portion of the Southern Great Plains. This change in precipitation was found to be strongest in the Oklahoma-Arkansas region where it reached about one third of the mean inter-annual variability in precipitation. The duration of this variation is about 20 years and continuing at the present time. The recurrence of these long-duration variations in mean annual precipitation suggest that agriculture in the Southern Great Plains, which is primarily based on dry-land farming, could benefit by adapting planning and management strategies to diversify and increase production during sustained periods of increased precipitation.

Technical Abstract: Over the last decades the recurrence of decade-scale precipitation fluctuations has been related to global scale phenomena. Thus, decade- scale precipitation fluctuations are not the result of random clustering of wet years, but appear to be related to low frequency ocean-atmosphere circulation patterns. This study investigates the characteristics of the latest decade-scale precipitation fluctuation in the Southern Great Plains Geographic extent of the study includes the states of Colorado, Nebraska, Kansas, Missouri, New Mexico, Oklahoma, Arkansas, Texas and Louisiana. Annual precipitation records of climate divisions of these states are the basis for this study. Results show that the precipitation fluctuation covers a large portion of the Southern Great Plains, and that it is strongest in the Oklahoma-Kansas region. The precipitation fluctuation begins in the 1980's and is ongoing. Its duration and intensity are the largest on record. The duration is, to date, about 20 years, and its intensity is about 30% of the long term inter annual-variability (expressed in standard deviation). The recurrence of decade-scale precipitation fluctuations suggest that agriculture in the Southern Great Plains, which is primarily based on dry-land farming and irrigation, could benefit from this climate information. Agricultural planning and management strategies could be developed to diversify and increase production during the years with increased precipitation.