Application of a tunable diode laser to the measurement of CH 4 and N 2 O fluxes from field to landscape scale using several micrometeorological techniques E. Pattey a, * , I.B. Strachan b , R.L. Desjardins a , G.C. Edwards a , D. Dow a , J.I. MacPherson c a Agriculture and Agri-Food Canada, Ottawa, Ont., Canada b Department of Natural Resource Sciences, McGill University, Montreal, QC, Canada c Formerly with Flight Laboratory of National Research Council, Ottawa, Ont., Canada Received 4 June 2004; received in revised form 9 November 2004; accepted 5 December 2004 Abstract Methane and nitrous oxide fluxes were measured at the field to landscape scale by combining tunable diode laser (TDL) technology with micrometeorological techniques. The three following micrometeorological measurement platform were used: (1) tower-based eddy covariance and flux-gradient techniques for measuring methane fluxes over the Canadian boreal forest and nitrous oxide over agricultural fields; (2) blimp-based nocturnal boundary layer (NBL) budget technique over agricultural areas for measuring nitrous oxide fluxes and (3) the NRC Twin Otter aircraft-based relaxed eddy accumulation (REA) to measure methane fluxes over the Canadian boreal forest. The techniques were applied using the TDL in situ (field applications) as well as in the laboratory (environmentally controlled conditions for very high resolution). The latter is accomplished by decoupling in situ air sample collection using PTFE bags from the actual air sample analysis using the TGA100. The application of the TDL to REA and NBL flux measurement is unique. Its versatility is illustrated using results obtained from experiments carried out at scales varying from field to farms to landscape. The results of these experiments clearly demonstrate the importance of knowing the variability of fluxes temporally and spatially to broach issues of scaling up to obtain fluxes representative of large areas. # 2005 Elsevier B.V. All rights reserved. Keywords: Tunable diode laser; Methane; Nitrous oxide; Eddy covariance; Relaxed eddy accumulation; Flux gradient; Nocturnal boundary layer budget 1. Introduction Early micrometeorological researchers (Scrase, 1930; Swinbank, 1951; Dyer, 1965; Chamberlain and Chadwick, 1953) faced difficult challenges as technol- ogy as we know it today was not available to carry out flux measurements. The first flux quantification using eddy covariance was done by hand using chart recordings (Scrase, 1930; Swinbank, 1951). Later micrometeorologists such as Marv Wesley were able to realize the previous generation’s dream of collecting data digitally with the advent of the personal computer, electronic data logging, and instruments that had sufficient response to make accurate measurements of heat, momentum, and water vapour. Marv Wesely was a pioneer of trace gas dry deposition measurement with his efforts in the 1970s and 1980s measuring gases and particles associated with the global environmental issue www.elsevier.com/locate/agrformet Agricultural and Forest Meteorology 136 (2006) 222–236 * Corresponding author. Fax: +1 613 759 1724. E-mail address: patteye@agr.gc.ca (E. Pattey). 0168-1923/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.agrformet.2004.12.009