The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Default user image.

Anders Lindroth

Professor

Default user image.

Evaluating the performance of commonly used gas analysers for methane eddy covariance flux measurements: the InGOS inter-comparison field experiment

Author

  • O. Peltola
  • A. Hensen
  • C. Helfter
  • L. Belelli Marchesini
  • F. C. Bosveld
  • W. C. M. van den Bulk
  • J. A. Elbers
  • S. Haapanala
  • Jutta Holst
  • T. Laurila
  • Anders Lindroth
  • E. Nemitz
  • T. Rockmann
  • A. T. Vermeulen
  • I. Mammarella
Show all

Summary, in English

The performance of eight fast-response methane (CH4) gas analysers suitable for eddy covariance flux measurements were tested at a grassland site near the Cabauw tall tower (Netherlands) during June 2012. The instruments were positioned close to each other in order to minimise the effect of varying turbulent conditions. The moderate CH4 fluxes observed at the location, of the order of 25 nmol m(-2) s(-1), provided a suitable signal for testing the instruments' performance. Generally, all analysers tested were able to quantify the concentration fluctuations at the frequency range relevant for turbulent exchange and were able to deliver high-quality data. The tested cavity ringdown spectrometer (CRDS) instruments from Picarro, models G2311-f and G1301-f, were superior to other CH4 analysers with respect to instrumental noise. As an open-path instrument susceptible to the effects of rain, the LI-COR LI-7700 achieved lower data coverage and also required larger density corrections; however, the system is especially useful for remote sites that are restricted in power availability. In this study the open-path LI-7700 results were compromised due to a data acquisition problem in our data-logging setup. Some of the older closed-path analysers tested do not measure H2O concentrations alongside CH4 (i.e. FMA1 and DLT-100 by Los Gatos Research) and this complicates data processing since the required corrections for dilution and spectroscopic interactions have to be based on external information. To overcome this issue, we used H2O mole fractions measured by other gas analysers, adjusted them with different methods and then applied them to correct the CH4 fluxes. Following this procedure we estimated a bias of the order of 0.1 g (CH4) m(-2) (8% of the measured mean flux) in the processed and corrected CH4 fluxes on a monthly scale due to missing H2O concentration measurements. Finally, cumulative CH4 fluxes over 14 days from three closed-path gas analysers, G2311-f (Picarro Inc.), FGGA (Los Gatos Research) and FMA2 (Los Gatos Research), which were measuring H2O concentrations in addition to CH4, agreed within 3% (355-367 mg (CH4) m(-2)) and were not clearly different from each other, whereas the other instruments derived total fluxes which showed small but distinct differences (+/- 10 %, 330-399 mg (CH4) m(-2)).

Department/s

  • Dept of Physical Geography and Ecosystem Science
  • eSSENCE: The e-Science Collaboration
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year

2014

Language

English

Pages

3163-3186

Publication/Series

Biogeosciences

Volume

11

Issue

12

Document type

Journal article

Publisher

Copernicus GmbH

Topic

  • Physical Geography

Status

Published

ISBN/ISSN/Other

  • ISSN: 1726-4189