Energetics of Large-Scale Motion in the Tropics During GATE at 250 mb

Colin A. Depradine Department of Meteorology, Florida State University, Tallahassee 32306

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Abstract

Use is made of a mixture of observing bases to provide a data set for the global tropics. This data set allows a reasonably good delineation of the tropical motion field at three levels, 200. 250 and 300 mb. An iterative procedure, used to initialize the Florida Side University multilevel primitive equation prediction model, is used to obtain potential fields which provide a temperature field at 250 mb. The kinematic method is used to obtain vertical motion fields.

Computations have been carried out for the conversion of available potential energy to kinetic energy for the first 15 wavenumbers at 250 mb. The largest conversions occurred for wavenumbers 1 and 2. Computations were also carried out for the wave-wave and wave-zonal-trasnfers of available potential energy and kinetic energy at same level. When these waves are divided into the three groups, long, medium and short, the results show that in the intergroup interactions for APE, the long waves receive energy from the shorter scale waves, whereas in the KE interactions, the long waves supply energy to the shorter scale waves. In the wave-zonal interactions all of the shorter scale waves received energy from the zonal flow both for APE and KE.

Abstract

Use is made of a mixture of observing bases to provide a data set for the global tropics. This data set allows a reasonably good delineation of the tropical motion field at three levels, 200. 250 and 300 mb. An iterative procedure, used to initialize the Florida Side University multilevel primitive equation prediction model, is used to obtain potential fields which provide a temperature field at 250 mb. The kinematic method is used to obtain vertical motion fields.

Computations have been carried out for the conversion of available potential energy to kinetic energy for the first 15 wavenumbers at 250 mb. The largest conversions occurred for wavenumbers 1 and 2. Computations were also carried out for the wave-wave and wave-zonal-trasnfers of available potential energy and kinetic energy at same level. When these waves are divided into the three groups, long, medium and short, the results show that in the intergroup interactions for APE, the long waves receive energy from the shorter scale waves, whereas in the KE interactions, the long waves supply energy to the shorter scale waves. In the wave-zonal interactions all of the shorter scale waves received energy from the zonal flow both for APE and KE.

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