Mapping of Forest Ecosystem Evapotranspiration by Using Results of EOS and Flux Tower observations

• Main Authors: Gornyy, V., Kritsuk, S., Latypov, I., Tronin, A., Brovkina, O. (Olga), Majasalmi, T.
• Format: Other/Unknown Material
• Language: English
• Published: 2016
• Subjects: evapotranspiration; forest; mapping; taiga
• Online Access: http://hdl.handle.net/11104/0266413

Evaporation from the land surface is needed to estimate regional water balance, which can be used for monitoring health of vegetated areas and ecosystem disturbances.\nThe usage of the heat budget equation of land surface is one of methodological approaches for the evaporation rate mapping on the base of Earth Observing System (EOS) imagery:\nLE=S*(1-A)-H-R-G, (1)\nwhere LE – the latent heat flux, W/m2; S – the incoming radiant energy (shortwave) falling on land surface at the angle, W/m2; A – albedo of land surface; H - the sensible heat flux, W/m2; R – the longwave radiation balance, W/m2; G – the heat flux in soil (ecosystem), caused by daily and annual thermal cycles, W/m2. \nThe land surface energy budget approach can be divided into two sub-approaches. The latent heat flux may be calculated as a residue from the heat budget equation, if other terms of equation (1) are known. The errors of the evaporation rate calculation depends on the errors of the eddy coefficient estimating. The best estimation of the eddy coefficient can be obtained by using flux towers. Alternatively, evaporation rate may be mapped using thermal inertia technique. It can be obtained on diurnal variation in surface temperature measured by satellite. This approach has minimum of initial assumptions and the small dependence of the results from instantaneous changes in the weather conditions. It requires the complicate calculation of the coefficient of turbulent heat transfer in the atmospheric surface layer.\nIn this study we combine the thermal inertia approach with flux tower observations to develop a technique of land surface evapotranspiration mapping. \nStudy area consists of taiga forest in southern part of Finland and Leningrad district of Russia. \nWe used results of multiple Terra/Aqua (MODIS) satellite survey and Hyytiälä (forest) and Siikaneva (marsh) flux towers (Finland) regime observations, as well as, the thermal inertia approach. After analyses of heat and moister fluxes the new empirical equations for coefficients of ...