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...
Published in: | Atmospheric Measurement Techniques |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Published by Copernicus Publications on behalf of the European Geosciences Union.
2018
|
Subjects: | |
Online Access: | https://epic.awi.de/id/eprint/47700/ https://epic.awi.de/id/eprint/47700/1/amt-11-4567-2018.pdf https://www.atmos-meas-tech.net/11/4567/2018/ https://hdl.handle.net/10013/epic.ca67bf83-ddcd-43f4-b140-b994b451993e |
id |
ftawi:oai:epic.awi.de:47700 |
---|---|
record_format |
openpolar |
spelling |
ftawi:oai:epic.awi.de:47700 2024-09-15T18:39:50+00:00 New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns Hartmann, Jörg Gehrmann, Martin Kohnert, Katrin Metzger, Stefan Sachs, Torsten 2018-07-31 application/pdf https://epic.awi.de/id/eprint/47700/ https://epic.awi.de/id/eprint/47700/1/amt-11-4567-2018.pdf https://www.atmos-meas-tech.net/11/4567/2018/ https://hdl.handle.net/10013/epic.ca67bf83-ddcd-43f4-b140-b994b451993e unknown Published by Copernicus Publications on behalf of the European Geosciences Union. https://epic.awi.de/id/eprint/47700/1/amt-11-4567-2018.pdf Hartmann, J. , Gehrmann, M. , Kohnert, K. , Metzger, S. and Sachs, T. (2018) New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns , Atmos. Meas. Tech., 11 (11), pp. 4567-4581 . doi:10.5194/amt-11-4567-2018 <https://doi.org/10.5194/amt-11-4567-2018> , hdl:10013/epic.ca67bf83-ddcd-43f4-b140-b994b451993e EPIC3Atmos. Meas. Tech., Published by Copernicus Publications on behalf of the European Geosciences Union., 11(11), pp. 4567-4581 Article isiRev 2018 ftawi https://doi.org/10.5194/amt-11-4567-2018 2024-06-24T04:19:47Z 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 4mgm−2d−1 for w′CH4′, 1.4gm−2d−1 for w′CO2′ and 4.2Wm−2 for the sensible heat flux. Article in Journal/Newspaper Tundra Alaska Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Atmospheric Measurement Techniques 11 7 4567 4581 |
institution |
Open Polar |
collection |
Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
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 4mgm−2d−1 for w′CH4′, 1.4gm−2d−1 for w′CO2′ and 4.2Wm−2 for the sensible heat flux. |
format |
Article in Journal/Newspaper |
author |
Hartmann, Jörg Gehrmann, Martin Kohnert, Katrin Metzger, Stefan Sachs, Torsten |
spellingShingle |
Hartmann, Jörg Gehrmann, Martin Kohnert, Katrin Metzger, Stefan Sachs, Torsten New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns |
author_facet |
Hartmann, Jörg Gehrmann, Martin Kohnert, Katrin Metzger, Stefan Sachs, Torsten |
author_sort |
Hartmann, Jörg |
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 |
Published by Copernicus Publications on behalf of the European Geosciences Union. |
publishDate |
2018 |
url |
https://epic.awi.de/id/eprint/47700/ https://epic.awi.de/id/eprint/47700/1/amt-11-4567-2018.pdf https://www.atmos-meas-tech.net/11/4567/2018/ https://hdl.handle.net/10013/epic.ca67bf83-ddcd-43f4-b140-b994b451993e |
genre |
Tundra Alaska |
genre_facet |
Tundra Alaska |
op_source |
EPIC3Atmos. Meas. Tech., Published by Copernicus Publications on behalf of the European Geosciences Union., 11(11), pp. 4567-4581 |
op_relation |
https://epic.awi.de/id/eprint/47700/1/amt-11-4567-2018.pdf Hartmann, J. , Gehrmann, M. , Kohnert, K. , Metzger, S. and Sachs, T. (2018) New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns , Atmos. Meas. Tech., 11 (11), pp. 4567-4581 . doi:10.5194/amt-11-4567-2018 <https://doi.org/10.5194/amt-11-4567-2018> , hdl:10013/epic.ca67bf83-ddcd-43f4-b140-b994b451993e |
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 |
_version_ |
1810484170590257152 |