Relations between Aerodynamic Parameters of Heat Transfer and Thermal-Infrared Thermometry in the Bulk Surface Formulation

Abstract

Disagreement of the thermal-infrared (TIR) surface temperature and the aerodynamic surface temperature, which is an effective surface temperature in estimating surface heat fluxes using the bulk method, is a critical problem in the combination of the TIR thermometry and the bulk method. The present study investigates two methods which adjust the disagreement. One is the method using the radiometric thermal roughness length, and the other is the method using empirical parameterizations (adjustment parameter method). Recent literature has shown a priority of the adjustment parameter method, however, the present study shows the radiometric thermal roughness length is analytically identical to the adjustment parameters, and it is verified by observation data that the two methods can be equally used in estimating sensible heat flux over a rice paddy, over a wide range of vegetation density. Moreover, it is shown that the adjustment parameters quantify the effect of viewing angle of measurement on the TIR surface temperature.