The Empirical Method of Estimating Mean Daily and Mean Ten-Day Values of Latent and Sensible-Heat Fluxes near the Ground

Abstract

A simple empirical scheme that relates the surface fluxes of latent and sensible heat to weather variables and to the relative height of plants is presented in this paper. The required input weather data are air temperature, wind speed, saturation vapor-pressure deficit, and relative sunshine. The scheme is designed for surfaces covered by alfalfa, wheat, rapeseed, meadow, and for bare soil, but it consists of parameters that can be adjusted to other coverages. The experiments were carried out at the experimental fields in Turew, about 50 km south of Poznan in West Poland, during the vegetation seasons 1982–85. The measurements of all meteorological elements needed for calculating sensible and latent-heat fluxes were carried out above different agroecosystems by using quartz psychrometers constructed in the Agrometeorology Department of the Agricultural University in Poznan. Mean component values of heat balance structure, calculated for four crops during four vegetation seasons, are given by: Rn = 86.4 W m−2, LE = −68.3 W m−2, H = − 14.0 W m−2, G = −4.1 W m−2.