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Diagnosis and Attribution of a Seasonal Precipitation Deficit in a U.S. Regional Climate Simulation
Journal of Hydrometeorology
  • William J. Gutowski, Jr., Iowa State University
  • Francis O. Otieno, Iowa State University
  • Raymond W. Arritt, Iowa State University
  • Eugene S. Takle, Iowa State University
  • Zaitao Pan, Iowa State University
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Precipitation from a 10-yr regional climate simulation is evaluated using three complementary analyses: self-organizing maps, bias scores, and arithmetic bias. Collectively, the three reveal a precipitation deficit in the south-central United States that emerges in September and lingers through February. Deficient precipitation for this region and time of year is also evident in other simulations, indicating a generic problem in climate simulation. Analysis of terrestrial and atmospheric water balances shows that the 10-yr average precipitation error for the region results primarily from a deficit in horizontal water vapor convergence. However, the 10-yr average for fall only suggests that the primary contributor is a deficit in evapotranspiration. Evaluation of simulated temperature and soil moisture suggests the model has insufficient terrestrial water for evaporation during fall. Results for winter are mixed; errors in both evapotranspiration and lateral moisture convergence may contribute substantially to the precipitation deficit. The model reproduces well both the time-average and time-filtered large-scale circulation, implying that the moisture convergence error arises from an error in simulating mesoscale circulation.

This article is from J. Hydrometeor, 5, 230–242. doi:<0230:DAAOAS>2.0.CO;2. Posted with permission.

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American Meteorological Society
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William J. Gutowski, Francis O. Otieno, Raymond W. Arritt, Eugene S. Takle, et al.. "Diagnosis and Attribution of a Seasonal Precipitation Deficit in a U.S. Regional Climate Simulation" Journal of Hydrometeorology Vol. 5 Iss. 1 (2004) p. 230 - 242
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