Hydrological Processes in Regional Climate Model Simulations of the Central United States Flood of June–July 1993

Christopher J. Anderson, Raymond W. Arritt, Zaitao Pan, Eugene S. Takle, William J. Gutowski, Francis O. Otieno, Renato da Silva, Daniel Caya, Jens H. Christensen, Daniel Lüthi, Miguel A. Gaertner, Clemente Gallardo (+13 others)
2003 Journal of Hydrometeorology  
Thirteen regional climate model (RCM) simulations of June-July 1993 were compared with each other and observations. Water vapor conservation and precipitation characteristics in each RCM were examined for a 10Њ ϫ 10Њ subregion of the upper Mississippi River basin, containing the region of maximum 60-day accumulated precipitation in all RCMs and station reports. All RCMs produced positive precipitation minus evapotranspiration (P Ϫ E Ͼ 0), though most RCMs produced P Ϫ E below the observed
more » ... RCM recycling ratios were within the range estimated from observations. No evidence of common errors of E was found. In contrast, common dry bias of P was found in the simulations. Daily cycles of terms in the water vapor conservation equation were qualitatively similar in most RCMs. Nocturnal maximums of P and C (convergence) occurred in 9 of 13 RCMs, consistent with observations. Three of the four driest simulations failed to couple P and C overnight, producing afternoon maximum P. Further, dry simulations tended to produce a larger fraction of their 60-day accumulated precipitation from low 3-h totals. In station reports, accumulation from high (low) 3-h totals had a nocturnal (early morning) maximum. This time lag occurred, in part, because many mesoscale convective systems had reached peak intensity overnight and had declined in intensity by early morning. None of the RCMs contained such a time lag. It is recommended that short-period experiments be performed to examine the ability of RCMs to simulate mesoscale convective systems prior to generating long-period simulations for hydroclimatology. ), suggesting that high-resolution models are necessary for detailed, physically based simulation of the region's hydroclimate. One approach to this problem is the use of a regional climate model (RCM) that nests a high-resolution limited-area model within the grid of a coarser-resolution analysis or climate model. A variety of RCM architectures exist, but systematic comparison of output from different RCMs is lacking (Giorgi and Mearns 1999) . In response to this need a number of
doi:10.1175/1525-7541(2003)004<0584:hpircm>2.0.co;2 fatcat:dv5yv3my2van3fnbvs34prlffy