Authors: P B Duffy B Govindasamy J P Iorio J Milovich K R Sperber K E Taylor M F Wehner S L Thompson
Publish Date: 2003/08/26
Volume: 21, Issue: 5-6, Pages: 371-390
Abstract
We examine simulations of todays climate performed with a global atmospheric general circulation model run at spectral truncations of T42 T170 and T239 corresponding to grid cell sizes of roughly 310 km 75 km and 55 km respectively The simulations were forced with observed seasurface temperatures and seaice concentrations The T42 simulations and initial simulations at T170 and T239 were performed using a model version that was carefully tuned to optimize results at T42 subsequent simulations at T170 and T239 used a model version that was partly retuned to improve results at T170 On the scales of a T42 grid cell and larger nearly all quantities we examined in all the T170 and T239 simulations agree better with observations at least in terms of spatial patterns than in the T42 simulations In some cases the improvements are very substantial Improvements are seen in allseason global domain results and in results pertaining to most seasons and latitude bands Increasing the model resolution from T42 introduces biases errors in the mean into some simulated quantities the worst of these were removed by the partial retuning we performed at T170 This retuning has little effect on the spatial patterns of results except in Northern Hemisphere winter at T170 where it tends to bring improvements We discuss aspects of simulated regional climates and their dependence on model resolutionThis work was performed under the auspices of the US Department of Energy by the Lawrence Livermore National Laboratory under contract W–7405Eng48 We thank J Hack for help with retuning the T170 model CPC US Unified Precipitation data was provided by the NOAACIRES Climate Diagnostics Center Boulder Colorado USA from their Web site at http//wwwcdcnoaagov/
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