Empirical Relations Between Seasonal Changes in Meridional Temperature Gradients and Meridional Fluxes of Heat

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  • 1 Department of Meteorology. Massachusetts Institute of Technology, Cambridge 02139
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Abstract

The correlation of the zonal mean meridional flux of heat in the atmosphere-ocean system and of its various components with the zonal mean 1000 mb meridional temperature gradient are calculated from analyses of the mean seasonal changes in these quantities. The correlations for the total atmospheric flux and its dominant components are typically 90% or more. The correlation of the eddy flux with the temperature gradient is particularly high (typically 97%) but only if the transient and stationary components are added together. There appears to be no correlation between the ocean flux and the temperature gradient in low latitudes.

In cases where the correlation is high, the seasonal changes are used to derive empirical relations between the fluxes and the gradient. Seasonal changes in the total flux in the atmosphere-ocean system are twice as strong as would be implied by a linear diffusion law. The empirical relations for the seasonal changes in the eddy flux of sensible heat indicate that it is approximately proportional to the square of the gradient in midlatitudes, but to the third or fourth power of the gradient near 30°N. This behavior is consistent with proposed parameterizations if β effects are small in midlatitudes but important near 30°N.

Abstract

The correlation of the zonal mean meridional flux of heat in the atmosphere-ocean system and of its various components with the zonal mean 1000 mb meridional temperature gradient are calculated from analyses of the mean seasonal changes in these quantities. The correlations for the total atmospheric flux and its dominant components are typically 90% or more. The correlation of the eddy flux with the temperature gradient is particularly high (typically 97%) but only if the transient and stationary components are added together. There appears to be no correlation between the ocean flux and the temperature gradient in low latitudes.

In cases where the correlation is high, the seasonal changes are used to derive empirical relations between the fluxes and the gradient. Seasonal changes in the total flux in the atmosphere-ocean system are twice as strong as would be implied by a linear diffusion law. The empirical relations for the seasonal changes in the eddy flux of sensible heat indicate that it is approximately proportional to the square of the gradient in midlatitudes, but to the third or fourth power of the gradient near 30°N. This behavior is consistent with proposed parameterizations if β effects are small in midlatitudes but important near 30°N.

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