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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2020-12-01
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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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