Methane distributions and transports in the nocturnal boundary layer at a rural station

Research output: Contribution to book/Conference proceedings/Anthology/ReportConference contributionContributedpeer-review

Contributors

  • Klaus Schäfer - , Karlsruhe Institute of Technology (Author)
  • Matthias Zeeman - , Karlsruhe Institute of Technology (Author)
  • Caroline Brosy - , Karlsruhe Institute of Technology (Author)
  • Christoph Münkel - , Weather Instruments (Author)
  • Benjamin Fersch - , Karlsruhe Institute of Technology (Author)
  • Matthias Mauder - , Karlsruhe Institute of Technology (Author)
  • Stefan Emeis - , Karlsruhe Institute of Technology (Author)

Abstract

To investigate the methane distributions and transports, the role of related atmospheric processes by determination of vertical profiles of wind, turbulence, temperature and humidity as well as nocturnal boundary layer (NBL) height and the quantification of methane emissions at local and plot scale the so-called ScaleX-campaign was performed in a pre-alpine observatory in Southern Germany from 01 June until 31 July 2015. The following measurements from the ground up to the free troposphere were performed: layering of the atmosphere by a ceilometer (Vaisala CL51); temperature, wind, turbulence profiles from 50 m up to 500 m by a Radio-Acoustic Sounding System (RASS, Metek GmbH); temperature, humidity profiles in situ by a hexacopter; methane farm emissions by two open-path laser spectrometers (Boreal GasFinder2); methane concentrations in situ (Los Gatos DLT-100) with tubes in 0.3 m agl and 5 sampling heads; and methane soil emissions by a big chamber (10 m length, 2.60 m width, up to 0.61 m height) with a plastic cover. The methane concentrations near the surface show a daily variation with a maximum and a frequent double-peak structure during night-time. Analysis of the variation of the nocturnal methane concentration together with the hexacopter and RASS data indicates that the first peak in the nocturnal methane concentration is probably due to local cooling and stabilization which keeps the methane emissions from the soil near the ground. The second peak seems to be due to advection of methane-enriched air which had formed in the environment of the nearby farm yards. These dairy farm emissions were determined by up-wind and down-wind open-path concentration measurements, turbulence data from an EC station nearby and Backward Lagrangian Simulation (WindTrax software). The methane fluxes at plot scale (big chamber) are characterized by emissions at water saturated grassland patches, by an exponential decrease of these emissions during grassland drying, and by an uptake of methane at dry grassland. Highest methane concentrations are found with lowest NBL heights which were determined from the ceilometer monitoring (correlation coefficient 0.56).

Details

Original languageEnglish
Title of host publicationRemote Sensing of Clouds and the Atmosphere XXI
EditorsKlaus Schafer, Adolfo Comeron, James W. Jack, Richard H. Picard, Konradin Weber, Evgueni I. Kassianov
PublisherSPIE - The international society for optics and photonics, Bellingham
ISBN (electronic)9781510604063
Publication statusPublished - 2016
Peer-reviewedYes
Externally publishedYes

Publication series

SeriesProceedings of SPIE - The International Society for Optical Engineering
Volume10001
ISSN0277-786X

Conference

TitleRemote Sensing of Clouds and the Atmosphere XXI
Duration28 - 29 September 2016
CityEdinburgh
CountryUnited Kingdom

External IDs

ORCID /0000-0002-8789-163X/work/168718963

Keywords

Keywords

  • ceilometer, Greenhouse gases, methane fluxes, nocturnal boundary layer, RASS, remote sensing