Surface heat flux estimates from NCAR electra data over the pacific warm pool during TOGA COARE

Abstract

The warm pool region of the western tropical Pacific is of particular interest to atmospheric dynamics because it represents a significant source of energy to the atmosphere. A better understanding of heat transfer driven by mesoscale and turbulent circulations within this region could lead to improved global circulation models, and therefore to improved prediction of global weather patterns. A first step to this understanding is to evaluate empirical data as well as the methods used to estimate heat transfer, or heat flux, at the surface. Of specific interest here are latent heat flux, the heat transfer associated with evaporation, and sensible heat flux, the heat transfer associated with convection and conduction. In this paper, two different methods of turbulent flux calculation, eddy correlation and the bulk aerodynamic method are compared. Eddy correlation directly uses turbulence measurements to estimate heat flux whereas the bulk aerodynamic method relies on similarity theory to relate heat flux to mean flow quantities. A brief discussion of selection of averaging length based on flight altitude is included, as well as a comparison of errors introduced in averaging velocity as a scalar or as a vector. Errors introduced by averaging, including mesoscale flux enhancement, are evaluated for strong and weak wind cases during relatively light convection in the region. Finally, month to month variability in heat flux is evaluated in an effort to further understand the accuracy of various approximations used in flux calculation

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