Evaluation of Selected Empirical Schemes of Calculating Sensible Heat Flux from Routinely-Measured Meteorological Parameters in a Tropical Location

Abstract

The accurate estimation of sensible heat flux (Hs) is imperative in the exchange of energy and mass between the earth’s systems. However, the process of acquiring the sensible heat flux data is challenging due to the complexity in its direct measurement hence, not readily available. The alternative is to use estimations which are derived from specific models. This study evaluated the performances of five selected schemes of estimating Hs from routinely-measured meteorological parameters using statistical methods such as Mean Bias Error (MBE), Mean Percentage Difference (MPD), Root Mean Square Error (RMSE), Index of Agreement (IA), Correlation Coefficient (R) and Coefficient of Determination (R2). The empirical schemes selected are: Berkowicz and Prahm (BP), Bowen Ratio Energy Balance (BREB), Holstlag and Van Ulden (HU), Smith (ST) and Surface Temperature (ST) schemes. The results obtained revealed that in the dry season, MBE values of 6.9 Wm-2, 7.2 Wm-2, 7.5 Wm-2, 6.3 Wm-2 and -3.8 Wm-2 were obtained for BP, BREB, HU, SMT and ST respectively. In the wet season, BP, BREB, HU, SMT and ST had MBE values of 37.4 Wm-2, 14.2 Wm-2, 4.2 Wm-2, 12.0 Wm-2 and -1.1 Wm-2 respectively. The MBEs, RMSEs and MPDs obtained for the schemes were higher in the wet season (about 70 %) than in the dry season; implying that the schemes performed better in the dry season than in the wet season. The study rated BREB as the best method of estimating the sensible heat flux at the study location having the lowest MBE, lowest MPD, lowest RMSE, high R, high R2 and high IA in both seasons.