Energy Transformation in Two Lower Tropospheric Jets Accompaning Storm Rainfalls

Kinetic energy budgets were prepared for lower tropospheric jet stream accompaning storm rainfalls of two courses in 1993 and 1994,with the use of analyses from a limited-area fine-mesh model (100× 100km²,ten layers) as well as objective analysis system. It shows that the generation rate of kinetic energy (K) by pressure forces is always two-three orders bigger than change rate of K for every time. But the average generation rate as 200—206W/m² respectively, and the former was a source of kinetic energy (characterized by a large-scale direct solenoidal circulation, the latter was a sink for subgrid-to grid-scale energy transfer,done by a indirect solenoidal circulation. So the kinetic energy changes of the small (subgrid-) scale flow (lead by storm motions) paralleled those of the large-scale flow. This indicates a need for considering the apparent phenomenon of negative viscosity in mesoscale numerical atmospheric modeling for prediction of storm rainfalls.

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