TITLE:
The Impact of a Heterogeneous Surface on Spatiotemporal Uncertainties of Sensible Heat, Latent Heat, and CO2 Flux Measured over the Secondary Forest
AUTHORS:
Nanami Sakai, Daisuke Komori, Masafumi Kon, Wonsik Kim
KEYWORDS:
Eddy Covariance, Fractional Uncertainty, Monin-Obukhov Similarity Theory, Simultaneous Flux Observation
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.12 No.3,
February
26,
2020
ABSTRACT: The turbulent fluxes, such as sensible and latent heat fluxes and CO2 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 CO2 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 CO2 environment was heterogeneous; however, sensible and latent heat environments were homogeneous because the source area received insolation uniformly. Therefore, the analytical results for the CO2 flux presented a different pattern from those exhibited by the analytical results of the latent and sensible heat fluxes.