Eddy correlation measurements of methane fluxes using a tunable diode laser at the Kinosheo Lake tower site during the Northern Wetlands Study (NOWES)

Abstract

As part of the Canadian Northern Wetlands Study (NOWES) measurements of methane flux were made at the Kinosheo Lake tower site for a 1‐month period during the 1990 summer intensive. The measurements were made with a diode‐laser‐based methane sensor using the eddy correlation technique. Measurements of the methane fluxes were made at two levels, 5 or 18 m. Approximately 900 half‐hour average methane flux measurements were obtained. Weak temporal and diurnal trends were observed in the data. Fluxes averaged over the study period showed an overall methane emission of 16 mg CH₄ m⁻² d⁻¹ with a daytime average of 20 mg CH₄ m⁻² d⁻¹ and a nighttime average of 9 mg CH₄ m⁻² d⁻¹. The effect of emission footprint was evident in the data. A strong relationship between the daily average methane flux and wet bog temperature at 20‐cm depth was observed.