Wednesday, 9 January 2013
Exhibit Hall 3 (Austin Convention Center)
In this study, we evaluate the annual and seasonal mean Lorenz atmospheric energy cycle based on two reanalysis data, the Modern Era Retrospective analysis for Research and Applications (MERRA) and the National Center for Environmental Prediction and the Department of Energy (NCEP R2) for a 30-year period (19792008). The energy cycle calculated from the two reanalysis datasets is largely consistent, but the energy cycle determined using the MERRA dataset is more active than that from the NCEP R2 dataset. For annual mean energy cycle, the difference between two reanalysis data in the global integral of energy components is about 5 %, whereas the conversion components shows larger difference of about 16 %, with the exception of C(PM, KM), which has a different sign in the global integrals. The latitude-height cross-section indicates that the difference in the energy cycle of the two reanalysis datasets is larger in the southern hemisphere than in the northern hemisphere. The conversion rates of mean available potential energy to mean kinetic energy [C(PM, KM)] and eddy available potential energy to eddy kinetic energy [C(PE, KE)] are also calculated using two formulations (so called v∙grad z' and ù∙á') for the two reanalysis datasets. The differences in the conversion rate between the two reanalysis datasets for the global integral are not appreciable for the two formulations. We used the Lorentz energy cycle to examine the causes of the sudden jump of winter mean temperature in the northern hemisphere in the late 1980s. To examine the changes in atmospheric energetics associated with temperature regime shift, the decadal variations of the Lorentz energy cycle, atmospheric circulation, and large-scale climate indices are analyzed. Preliminary results will be discussed in this poster.
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