|Su, Z - WAGENINGEN UNIVERSITY|
|Massman, W - USDA-FOREST SERVICES|
Submitted to: European Geophysical Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 12, 2001
Publication Date: N/A
Technical Abstract: Roughness height for heat transfer is a crucial parameter in parameterization of the land-atmosphere heat transfer in global hydrological and atmospheric models. Although many empirical formulations have been proposed over the past few decades, the uncertainties associated with these formulations are shown to be large, especially over sparse canopies. In this contribution, a simple physically based model is derived for the estimation of the roughness height for heat transfer. This model is derived from a complex physical model based on the 'localized near-field' Lagrangian theory. The model is evaluated using three experimental data sets. The results of the model performances are judged by using the derived roughness values to compute sensible heat fluxes with the bulk transfer formulation, and comparing these computed fluxes to the observed sensible heat fluxes. It is concluded, on the basis of comparison of calculated versus observed sensible heat fluxes, that the present model provide reliable estimates of the roughness heights for heat transfer. The present model is further shown to be able to explain the diurnal variation in the roughness height for heat transfer. On the basis of a sensitivity analysis, it is suggested that although demanding, most of the information needed for the present model is amendable by satellite remote sensing such that their global utility into large-scale atmospheric models for both numerical weather predictions and climate research merits further investigation.