Field Evaluation of Column CO2 Retrievals From Intensity‐Modulated Continuous‐Wave Differential Absorption Lidar Measurements During the ACT‐America Campaign

Abstract We present an evaluation of airborne intensity‐modulated continuous‐wave (IM‐CW) lidar measurements of atmospheric column CO2 mole fractions during the Atmospheric Carbon and Transport–America (ACT‐America) project. This lidar system transmits online and offline wavelengths simultaneously o...

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Main Authors: Joel F. Campbell, Bing Lin, Jeremy Dobler, Sandip Pal, Kenneth Davis, Michael D. Obland, Wayne Erxleben, Doug McGregor, Chris O'Dell, Emily Bell, Brad Weir, Tai‐Fang Fan, Susan Kooi, Iouli Gordon, Abigail Corbett, Roman Kochanov
Format: Article
Language:English
Published: American Geophysical Union (AGU) 2020-12-01
Series:Earth and Space Science
Subjects:
CO2
Online Access:https://doi.org/10.1029/2019EA000847
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spelling doaj-507c3b6f72554d699fecf0f5a55fd7052021-03-01T10:38:57ZengAmerican Geophysical Union (AGU)Earth and Space Science2333-50842020-12-01712n/an/a10.1029/2019EA000847Field Evaluation of Column CO2 Retrievals From Intensity‐Modulated Continuous‐Wave Differential Absorption Lidar Measurements During the ACT‐America CampaignJoel F. Campbell0Bing Lin1Jeremy Dobler2Sandip Pal3Kenneth Davis4Michael D. Obland5Wayne Erxleben6Doug McGregor7Chris O'Dell8Emily Bell9Brad Weir10Tai‐Fang Fan11Susan Kooi12Iouli Gordon13Abigail Corbett14Roman Kochanov15NASA Langley Research Center (LaRC) Hampton VA USANASA Langley Research Center (LaRC) Hampton VA USASpectral Sensor Solutions LLC Albuquerque NM USAAtmospheric Science Division Texas Tech University Lubbock TX USANASA Langley Research Center The Pennsylvania State University State College PA USANASA Langley Research Center (LaRC) Hampton VA USAL3Harris Technologies Melbourne FL USASpectral Sensor Solutions LLC Albuquerque NM USADepartment of Geosciences Colorado State University Fort Collins CO USADepartment of Geosciences Colorado State University Fort Collins CO USAUniversities Space Research Association Columbia MD USAScience System and Application, Inc. Lanham MD USAScience System and Application, Inc. Lanham MD USAHarvard‐Smithsonian Center for Astrophysics Cambridge MA USAScience System and Application, Inc. Lanham MD USALaboratory of Theoretical Spectroscopy V.E. Zuev Institute of Atmospheric Optics Tomsk RussiaAbstract We present an evaluation of airborne intensity‐modulated continuous‐wave (IM‐CW) lidar measurements of atmospheric column CO2 mole fractions during the Atmospheric Carbon and Transport–America (ACT‐America) project. This lidar system transmits online and offline wavelengths simultaneously on the 1.57111‐μm CO2 absorption line, with each modulated wavelength using orthogonal swept frequency waveforms. After the spectral characteristics of this system were calibrated through short‐path measurements, we used the HITRAN spectroscopic database to calculate the average‐column CO2 mole fraction (XCO2) from the lidar‐measured optical depths. Using in situ measurements of meteorological parameters and CO2 concentrations for calibration data, we demonstrate that our lidar CO2 measurements were consistent from season to season and had an absolute calibration error (standard deviation) of 0.80 ppm when compared to XCO2 values calculated from in situ measurements. By using a 10‐s or longer moving average, a precision of 1 ppm or better was obtained. The estimated CO2 measurement precision for 0.1‐, 1‐, 10‐, and 60‐s averages was determined to be 3.4, 1.2, 0.43, and 0.26 ppm, respectively. These correspond to measurement signal‐to‐noise ratios of 120, 330, 950, and 1,600, respectively. The drift in XCO2 over 1‐hr of flight time was found to be below 0.1 ppm. These analyses demonstrate that the measurement stability, precision, and accuracy are all well below the thresholds needed to study synoptic‐scale variations in atmospheric XCO2.https://doi.org/10.1029/2019EA000847absorptionCO2instrumentationlaserlidarspectroscopy
collection DOAJ
language English
format Article
sources DOAJ
author Joel F. Campbell
Bing Lin
Jeremy Dobler
Sandip Pal
Kenneth Davis
Michael D. Obland
Wayne Erxleben
Doug McGregor
Chris O'Dell
Emily Bell
Brad Weir
Tai‐Fang Fan
Susan Kooi
Iouli Gordon
Abigail Corbett
Roman Kochanov
spellingShingle Joel F. Campbell
Bing Lin
Jeremy Dobler
Sandip Pal
Kenneth Davis
Michael D. Obland
Wayne Erxleben
Doug McGregor
Chris O'Dell
Emily Bell
Brad Weir
Tai‐Fang Fan
Susan Kooi
Iouli Gordon
Abigail Corbett
Roman Kochanov
Field Evaluation of Column CO2 Retrievals From Intensity‐Modulated Continuous‐Wave Differential Absorption Lidar Measurements During the ACT‐America Campaign
Earth and Space Science
absorption
CO2
instrumentation
laser
lidar
spectroscopy
author_facet Joel F. Campbell
Bing Lin
Jeremy Dobler
Sandip Pal
Kenneth Davis
Michael D. Obland
Wayne Erxleben
Doug McGregor
Chris O'Dell
Emily Bell
Brad Weir
Tai‐Fang Fan
Susan Kooi
Iouli Gordon
Abigail Corbett
Roman Kochanov
author_sort Joel F. Campbell
title Field Evaluation of Column CO2 Retrievals From Intensity‐Modulated Continuous‐Wave Differential Absorption Lidar Measurements During the ACT‐America Campaign
title_short Field Evaluation of Column CO2 Retrievals From Intensity‐Modulated Continuous‐Wave Differential Absorption Lidar Measurements During the ACT‐America Campaign
title_full Field Evaluation of Column CO2 Retrievals From Intensity‐Modulated Continuous‐Wave Differential Absorption Lidar Measurements During the ACT‐America Campaign
title_fullStr Field Evaluation of Column CO2 Retrievals From Intensity‐Modulated Continuous‐Wave Differential Absorption Lidar Measurements During the ACT‐America Campaign
title_full_unstemmed Field Evaluation of Column CO2 Retrievals From Intensity‐Modulated Continuous‐Wave Differential Absorption Lidar Measurements During the ACT‐America Campaign
title_sort field evaluation of column co2 retrievals from intensity‐modulated continuous‐wave differential absorption lidar measurements during the act‐america campaign
publisher American Geophysical Union (AGU)
series Earth and Space Science
issn 2333-5084
publishDate 2020-12-01
description Abstract We present an evaluation of airborne intensity‐modulated continuous‐wave (IM‐CW) lidar measurements of atmospheric column CO2 mole fractions during the Atmospheric Carbon and Transport–America (ACT‐America) project. This lidar system transmits online and offline wavelengths simultaneously on the 1.57111‐μm CO2 absorption line, with each modulated wavelength using orthogonal swept frequency waveforms. After the spectral characteristics of this system were calibrated through short‐path measurements, we used the HITRAN spectroscopic database to calculate the average‐column CO2 mole fraction (XCO2) from the lidar‐measured optical depths. Using in situ measurements of meteorological parameters and CO2 concentrations for calibration data, we demonstrate that our lidar CO2 measurements were consistent from season to season and had an absolute calibration error (standard deviation) of 0.80 ppm when compared to XCO2 values calculated from in situ measurements. By using a 10‐s or longer moving average, a precision of 1 ppm or better was obtained. The estimated CO2 measurement precision for 0.1‐, 1‐, 10‐, and 60‐s averages was determined to be 3.4, 1.2, 0.43, and 0.26 ppm, respectively. These correspond to measurement signal‐to‐noise ratios of 120, 330, 950, and 1,600, respectively. The drift in XCO2 over 1‐hr of flight time was found to be below 0.1 ppm. These analyses demonstrate that the measurement stability, precision, and accuracy are all well below the thresholds needed to study synoptic‐scale variations in atmospheric XCO2.
topic absorption
CO2
instrumentation
laser
lidar
spectroscopy
url https://doi.org/10.1029/2019EA000847
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