TREE SPECIES CLASSIFICATION OF BROADLEAVED FORESTS IN NAGANO, CENTRAL JAPAN, USING AIRBORNE LASER DATA AND MULTISPECTRAL IMAGES

Dense canopy weakens turbulent mixing, leading to significant CO₂ storage (F_s), a key part of net ecosystem exchange (NEE) measured using eddy covariance. Gust-biased F_s measurements complicate NEE estimation in forests with complex terrain. We analyzed gust-induced CO₂ fluctuations and their impact on F_s. F_s and its contribution to NEE can be explained by terrain complexity and turbulent mixing. This work highlights how gusts over complex terrain affect the F_s and NEE measurements.

Overall accuracy of CO₂/H₂O data from open-path eddy-covariance systems is modeled for data analysis. The model is further formulated into CO₂ and H₂O accuracy equations for uses. Based on atmospheric physics and bio-environment, both equations are used to evaluate accuracy of ecosystem CO₂/H₂O data and, as rationales, to assess field CO₂/H₂O zero and span procedures for the systems. The procedures are assessed for measurement improvement. An impractical H₂O span while cold is found unnecessary.

Air temperature from sonic temperature and air moisture has been used without an exact equation. We present an exact equation of such air temperature for closed-path eddy-covariance flux measurements. Air temperature from this equation is equivalent to sonic temperature in its accuracy and frequency response. It is a choice for advanced flux topics because, with it, thermodynamic variables in the flux measurements can be temporally synchronized and spatially matched at measurement scales.

The three-dimensional wind and sonic temperature data from a physically deformed sonic anemometer was successfully recovered by developing equations, algorithms, and related software. Using two sets of geometry data from production calibration and return re-calibration, this algorithm can recover wind with/without transducer shadow correction and sonic temperature with crosswind correction, and then obtain fluxes at quality as expected. This study is applicable as a reference for related topics.