Global-Scale Weekly and Monthly Energetics During January and February 1979

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  • 1 Department of Meteorology, University of Utah, Salt Lake City 84112
  • | 2 Laboratory for Atmospheric Sciences, NASA/Goddard Space Flight Center, Greenbelt, MD 20771
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Abstract

Time averages of the latitudinal distribution of kinetic energy and terms of the kinetic energy equation are presented as depicted by the Goddard Laboratory for Atmospheric Science (GLAS) analyses of the First GARP Global Experiment (FGGE) during the First Special Observing Period (SOP-1). Monthly averages display peaks in the stationary wave energy at 30°N and in the tropics. Global decompositions of the streamfunction and velocity potential in spherical harmonics are truncated at the fourth degree. The kinetic energy distribution of the associated wind field displays peaks in the tropics and northern mid-latitudes in January, but only a tropical peak in February.

The Eliassen-Palm relationship for latitudinal momentum and geopotential wave transport appears to have some support in these analyses, particularly in the mid-latitudes. In the deep tropics, latitudinal convergence of the fully resolved stationary wave momentum transport accompanies latitudinal convergence of stationary wave geopotential flux in westerly flow, in contradiction to this relationship.

Such results make it difficult to interpret time averages in terms of idealized wave propagation and linear theories. However, there is an interesting correspondence between observed weekly averages of the global-scale kinetic energy and the zonally averaged wind.

Abstract

Time averages of the latitudinal distribution of kinetic energy and terms of the kinetic energy equation are presented as depicted by the Goddard Laboratory for Atmospheric Science (GLAS) analyses of the First GARP Global Experiment (FGGE) during the First Special Observing Period (SOP-1). Monthly averages display peaks in the stationary wave energy at 30°N and in the tropics. Global decompositions of the streamfunction and velocity potential in spherical harmonics are truncated at the fourth degree. The kinetic energy distribution of the associated wind field displays peaks in the tropics and northern mid-latitudes in January, but only a tropical peak in February.

The Eliassen-Palm relationship for latitudinal momentum and geopotential wave transport appears to have some support in these analyses, particularly in the mid-latitudes. In the deep tropics, latitudinal convergence of the fully resolved stationary wave momentum transport accompanies latitudinal convergence of stationary wave geopotential flux in westerly flow, in contradiction to this relationship.

Such results make it difficult to interpret time averages in terms of idealized wave propagation and linear theories. However, there is an interesting correspondence between observed weekly averages of the global-scale kinetic energy and the zonally averaged wind.

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