The Impact of a Heterogeneous Surface on Spatiotemporal Uncertainties of Sensible Heat, Latent Heat, and CO₂ Flux Measured over the Secondary Forest

Abstract

The turbulent fluxes, such as sensible and latent heat fluxes and CO 2 flux, are globally observed over various terrestrial areas in order to understand the interaction between biosphere and atmosphere. Although the turbulent flux observations are generally performed on a horizontally homogeneous surface, the spatial distribution of the soil moisture is not homogeneous even on cultivated land with homogeneous vegetation, indicating that the development of each plant would be different and that the plant physiology, such as photosynthesis and growth, would be heterogeneous. In this study, to clarify the impact of a heterogeneous surface on spatiotemporal uncertainty of turbulent fluxes, a simultaneous flux observation experiment was conducted at different heights (20 m and 30 m) above the ground surface in a secondary seasonal tropical forest located in the Tak Province, Thailand. We defined ε as the spatial uncertainty of the turbulent flow flux, as proposed by Kim et al. (2011b) [ 1 ], and observed that ε of CO 2 flux was high, whereas ε of sensible and latent heat fluxes were low. This is likely to be caused by spatial uncertainty such as a heterogeneous surface. The CO 2 environment was heterogeneous; however, sensible and latent heat environments were homogeneous because the source area received insolation uniformly. Therefore, the analytical results for the CO 2 flux presented a different pattern from those exhibited by the analytical results of the latent and sensible heat fluxes.