New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns
Low-level flights over tundra wetlands in Alaska and Canada have been conducted during the Airborne Measurements of Methane Emissions (AirMeth) campaigns to measure turbulent methane fluxes in the atmosphere. In this paper we describe the instrumentation and new calibration procedures for the essent...
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ftdoajarticles:oai:doaj.org/article:a53db22a3b6b49cf9127aadef762bfc7 2023-05-15T18:40:34+02:00 New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns J. Hartmann M. Gehrmann K. Kohnert S. Metzger T. Sachs 2018-07-01T00:00:00Z https://doi.org/10.5194/amt-11-4567-2018 https://doaj.org/article/a53db22a3b6b49cf9127aadef762bfc7 EN eng Copernicus Publications https://www.atmos-meas-tech.net/11/4567/2018/amt-11-4567-2018.pdf https://doaj.org/toc/1867-1381 https://doaj.org/toc/1867-8548 doi:10.5194/amt-11-4567-2018 1867-1381 1867-8548 https://doaj.org/article/a53db22a3b6b49cf9127aadef762bfc7 Atmospheric Measurement Techniques, Vol 11, Pp 4567-4581 (2018) Environmental engineering TA170-171 Earthwork. Foundations TA715-787 article 2018 ftdoajarticles https://doi.org/10.5194/amt-11-4567-2018 2022-12-31T13:24:45Z Low-level flights over tundra wetlands in Alaska and Canada have been conducted during the Airborne Measurements of Methane Emissions (AirMeth) campaigns to measure turbulent methane fluxes in the atmosphere. In this paper we describe the instrumentation and new calibration procedures for the essential pressure parameters required for turbulence sensing by aircraft that exploit suitable regular measurement flight legs without the need for dedicated calibration patterns. We estimate the accuracy of the mean wind and the turbulence measurements. We show that airborne measurements of turbulent fluxes of methane and carbon dioxide using cavity ring-down spectroscopy trace gas analysers together with established turbulence equipment achieve a relative accuracy similar to that of measurements of sensible heat flux if applied during low-level flights over natural area sources. The inertial subrange of the trace gas fluctuations cannot be resolved due to insufficient high-frequency precision of the analyser, but, since this scatter is uncorrelated with the vertical wind velocity, the covariance and thus the flux are reproduced correctly. In the covariance spectra the −7∕3 drop-off in the inertial subrange can be reproduced if sufficient data are available for averaging. For convective conditions and flight legs of several tens of kilometres we estimate the flux detection limit to be about 4 mg m −2 d −1 for w ′CH 4 ′ , 1.4 g m −2 d −1 for w ′CO 2 ′ and 4.2 W m −2 for the sensible heat flux. Article in Journal/Newspaper Tundra Alaska Directory of Open Access Journals: DOAJ Articles Canada Atmospheric Measurement Techniques 11 7 4567 4581 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 |
spellingShingle |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 J. Hartmann M. Gehrmann K. Kohnert S. Metzger T. Sachs New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns |
topic_facet |
Environmental engineering TA170-171 Earthwork. Foundations TA715-787 |
description |
Low-level flights over tundra wetlands in Alaska and Canada have been conducted during the Airborne Measurements of Methane Emissions (AirMeth) campaigns to measure turbulent methane fluxes in the atmosphere. In this paper we describe the instrumentation and new calibration procedures for the essential pressure parameters required for turbulence sensing by aircraft that exploit suitable regular measurement flight legs without the need for dedicated calibration patterns. We estimate the accuracy of the mean wind and the turbulence measurements. We show that airborne measurements of turbulent fluxes of methane and carbon dioxide using cavity ring-down spectroscopy trace gas analysers together with established turbulence equipment achieve a relative accuracy similar to that of measurements of sensible heat flux if applied during low-level flights over natural area sources. The inertial subrange of the trace gas fluctuations cannot be resolved due to insufficient high-frequency precision of the analyser, but, since this scatter is uncorrelated with the vertical wind velocity, the covariance and thus the flux are reproduced correctly. In the covariance spectra the −7∕3 drop-off in the inertial subrange can be reproduced if sufficient data are available for averaging. For convective conditions and flight legs of several tens of kilometres we estimate the flux detection limit to be about 4 mg m −2 d −1 for w ′CH 4 ′ , 1.4 g m −2 d −1 for w ′CO 2 ′ and 4.2 W m −2 for the sensible heat flux. |
format |
Article in Journal/Newspaper |
author |
J. Hartmann M. Gehrmann K. Kohnert S. Metzger T. Sachs |
author_facet |
J. Hartmann M. Gehrmann K. Kohnert S. Metzger T. Sachs |
author_sort |
J. Hartmann |
title |
New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns |
title_short |
New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns |
title_full |
New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns |
title_fullStr |
New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns |
title_full_unstemmed |
New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns |
title_sort |
new calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the airmeth campaigns |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
https://doi.org/10.5194/amt-11-4567-2018 https://doaj.org/article/a53db22a3b6b49cf9127aadef762bfc7 |
geographic |
Canada |
geographic_facet |
Canada |
genre |
Tundra Alaska |
genre_facet |
Tundra Alaska |
op_source |
Atmospheric Measurement Techniques, Vol 11, Pp 4567-4581 (2018) |
op_relation |
https://www.atmos-meas-tech.net/11/4567/2018/amt-11-4567-2018.pdf https://doaj.org/toc/1867-1381 https://doaj.org/toc/1867-8548 doi:10.5194/amt-11-4567-2018 1867-1381 1867-8548 https://doaj.org/article/a53db22a3b6b49cf9127aadef762bfc7 |
op_doi |
https://doi.org/10.5194/amt-11-4567-2018 |
container_title |
Atmospheric Measurement Techniques |
container_volume |
11 |
container_issue |
7 |
container_start_page |
4567 |
op_container_end_page |
4581 |
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1766229956247945216 |