INFLUENCE OF EDDY COVARIANCE SENSOR HEIGHT ABOVE THE OIL PALM CANOPY ON CO2 AND ENERGY FLUXES

A study was carried out to determine the influence of eddy covariance (EC) sensor placement above the oil palm canopy on footprint, CO2, and energy fluxes. The study was carried out on 18-year old oil palms planted on mineral soil at an inland location in Peninsular Malaysia. Measurements were done from July to September 2016. The open path CO2/H2O analyser and 3-D sonic anemometer were initially installed at 30 m height. Both sensors were later repositioned at 19 m height on 2 August 2016. The different sensor heights had a significant effect on the diurnal CO2 fluxes above the oil palm canopy. The average CO2 flux measured was about -3.77 mu mol CO2 m(-2) at 30 m and was reduced to -0.75 mu mol CO2 m(-2) s(-1) at 19 m height. Lowering the sensor height also reduced the CO2 flux footprint by about 40% to a distance of 584 m. The energy imbalance is evident at the two different sensor heights and needs to be further studied.