0000000000189783
AUTHOR
Alain Perrier
Radiative surface temperature and convective flux calculation over crop canopies
The analysis presented in this paper aims at a better understanding of the potential role of radiative temperature, as measured by a radiometer over crops, in sensible heat flux calculation. Defining radiative temperature as the mean temperature of the surfaces viewed by the radiometer (leaves and soil surface) and assuming that an Ohm's law type formula can be used to express sensible heat flux as a function of the difference between air temperature and radiative temperature, the aerodynamic resistance which divides this temperature difference has been analytically defined. The parameters which appear in the resistance expression depend essentially on wind velocity and canopy structure but…
A prediction model for field drying of hay using a heat balance method
Abstract A hay drying model with a multi-layer representation has been developed. This model, based on a heat balance method, was designed to compute hay drying dynamics in the field. It was implemented for hay spread over a field or in windrows. The necessary inputs are: (1) meteorological data (temperature, humidity, wind speed, solar and atmospheric radiation); (2) biological characteristics of the plant; (3) hay physical parameters (depth, leaf area index). The output provides time-dependent cumulative water losses and changes in water content and temperature in the different layers. The model was tested against data measured under experimental conditions with different kinds of grass (…
Evaporation over land-surfaces: first results from HAPEX-MOBILHY special observing period
International audience
Land surface processes: description, theoretical approaches, and physical laws underlying their measurements
For more than a decade, evidence has accumulated from climate model experiments that the exchanges of momentum, heat, and moisture at the surface are phenomena that strongly influence the dynamics and thermodynamics of the atmosphere.