Study on the Impact of the Doppler Shift for CO<sub>2</sub> Lidar Remote Sensing
Atmospheric carbon dioxide (CO<sub>2</sub>) is recognized as the most important component of the greenhouse gases, the concentration of which has increased rapidly since the pre-industrial era due to anthropogenic emissions of greenhouse gases (GHG). The accurate monitoring of carbon dio...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-09-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/14/18/4620 |
| _version_ | 1797482812961456128 |
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| author | Xifeng Cao Lu Zhang Xingying Zhang Sen Yang Zhili Deng Xin Zhang Yuhan Jiang |
| author_facet | Xifeng Cao Lu Zhang Xingying Zhang Sen Yang Zhili Deng Xin Zhang Yuhan Jiang |
| author_sort | Xifeng Cao |
| collection | DOAJ |
| description | Atmospheric carbon dioxide (CO<sub>2</sub>) is recognized as the most important component of the greenhouse gases, the concentration of which has increased rapidly since the pre-industrial era due to anthropogenic emissions of greenhouse gases (GHG). The accurate monitoring of carbon dioxide is essential to study the global carbon cycle and radiation budget on Earth. The Aerosol and Carbon Detection Lidar (ACDL) instrument onboard the Atmospheric Environmental Monitoring Satellite (AEMS) was successfully launched in April 2022, which allows a new perspective to quantify the global spatial distribution of atmospheric CO<sub>2</sub> with high accuracy. In this work, the impact of the Doppler shift on CO<sub>2</sub> measurements for an integrated-path differential absorption (IPDA) light detection and ranging (lidar) system was evaluated to meet the weighted column-averaged mixing ratio of carbon dioxide (XCO<sub>2</sub>) measurement requirements of less than one part per million (ppm). The measurement uncertainties due to the Doppler shift were first evaluated in airborne IPDA observations. The result shows that most of the Doppler shift is in the range of 6–8 MHz, resulting in 0.26-0.39 ppm deviations in the XCO<sub>2</sub> results. The deviations between the XCO<sub>2</sub> retrievals and in situ measurements decreased to 0.16 ppm after the correction of the Doppler shift from 11:28:29 to 11:28:49 in the flight campaign. In addition, the online Doppler shift accounts for 98% of the deviations between XCO<sub>2</sub> retrievals and in situ measurements. Furthermore, the impact of the Doppler shift on ACDL measurements is also assessed. The differences between the XCO<sub>2</sub> retrievals with and without Doppler shift are used to quantify measurement uncertainties due to the Doppler effect. The simulations reveal that a pointing misalignment of 0.067 mrad can lead to a mean bias of about 0.30 ppm (0.072%) in the CO<sub>2</sub> column. In addition, CO<sub>2</sub> measurements are more sensitive to the Doppler shift at high altitudes for IPDA lidar, so the largest differences in the CO<sub>2</sub> columns are found on the Qinghai–Tibet Plateau in China. |
| first_indexed | 2024-03-09T22:37:51Z |
| format | Article |
| id | doaj.art-8730c487b3414a61ac683e5334a311f9 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-09T22:37:51Z |
| publishDate | 2022-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-8730c487b3414a61ac683e5334a311f92023-11-23T18:45:45ZengMDPI AGRemote Sensing2072-42922022-09-011418462010.3390/rs14184620Study on the Impact of the Doppler Shift for CO<sub>2</sub> Lidar Remote SensingXifeng Cao0Lu Zhang1Xingying Zhang2Sen Yang3Zhili Deng4Xin Zhang5Yuhan Jiang6Department of Atmospheric and Oceanic Sciences & Institute of Atmospheric Sciences, Fudan University, Shanghai 200438, ChinaKey Laboratory of Radiometric Calibration and Validation for Environmental Satellites, National Satellite Meteorological Center (National Center for Space Weather) and Innovation Center for FengYun Meteorological Satellite (FYSIC), China Meteorological Administration (CMA), Beijing 100081, ChinaKey Laboratory of Radiometric Calibration and Validation for Environmental Satellites, National Satellite Meteorological Center (National Center for Space Weather) and Innovation Center for FengYun Meteorological Satellite (FYSIC), China Meteorological Administration (CMA), Beijing 100081, ChinaChinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing 100081, ChinaChinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing 100081, ChinaChinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing 100081, ChinaChinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing 100081, ChinaAtmospheric carbon dioxide (CO<sub>2</sub>) is recognized as the most important component of the greenhouse gases, the concentration of which has increased rapidly since the pre-industrial era due to anthropogenic emissions of greenhouse gases (GHG). The accurate monitoring of carbon dioxide is essential to study the global carbon cycle and radiation budget on Earth. The Aerosol and Carbon Detection Lidar (ACDL) instrument onboard the Atmospheric Environmental Monitoring Satellite (AEMS) was successfully launched in April 2022, which allows a new perspective to quantify the global spatial distribution of atmospheric CO<sub>2</sub> with high accuracy. In this work, the impact of the Doppler shift on CO<sub>2</sub> measurements for an integrated-path differential absorption (IPDA) light detection and ranging (lidar) system was evaluated to meet the weighted column-averaged mixing ratio of carbon dioxide (XCO<sub>2</sub>) measurement requirements of less than one part per million (ppm). The measurement uncertainties due to the Doppler shift were first evaluated in airborne IPDA observations. The result shows that most of the Doppler shift is in the range of 6–8 MHz, resulting in 0.26-0.39 ppm deviations in the XCO<sub>2</sub> results. The deviations between the XCO<sub>2</sub> retrievals and in situ measurements decreased to 0.16 ppm after the correction of the Doppler shift from 11:28:29 to 11:28:49 in the flight campaign. In addition, the online Doppler shift accounts for 98% of the deviations between XCO<sub>2</sub> retrievals and in situ measurements. Furthermore, the impact of the Doppler shift on ACDL measurements is also assessed. The differences between the XCO<sub>2</sub> retrievals with and without Doppler shift are used to quantify measurement uncertainties due to the Doppler effect. The simulations reveal that a pointing misalignment of 0.067 mrad can lead to a mean bias of about 0.30 ppm (0.072%) in the CO<sub>2</sub> column. In addition, CO<sub>2</sub> measurements are more sensitive to the Doppler shift at high altitudes for IPDA lidar, so the largest differences in the CO<sub>2</sub> columns are found on the Qinghai–Tibet Plateau in China.https://www.mdpi.com/2072-4292/14/18/4620carbon dioxide (CO<sub>2</sub>)AEMSACDL lidarDoppler shiftaccuracy |
| spellingShingle | Xifeng Cao Lu Zhang Xingying Zhang Sen Yang Zhili Deng Xin Zhang Yuhan Jiang Study on the Impact of the Doppler Shift for CO<sub>2</sub> Lidar Remote Sensing Remote Sensing carbon dioxide (CO<sub>2</sub>) AEMS ACDL lidar Doppler shift accuracy |
| title | Study on the Impact of the Doppler Shift for CO<sub>2</sub> Lidar Remote Sensing |
| title_full | Study on the Impact of the Doppler Shift for CO<sub>2</sub> Lidar Remote Sensing |
| title_fullStr | Study on the Impact of the Doppler Shift for CO<sub>2</sub> Lidar Remote Sensing |
| title_full_unstemmed | Study on the Impact of the Doppler Shift for CO<sub>2</sub> Lidar Remote Sensing |
| title_short | Study on the Impact of the Doppler Shift for CO<sub>2</sub> Lidar Remote Sensing |
| title_sort | study on the impact of the doppler shift for co sub 2 sub lidar remote sensing |
| topic | carbon dioxide (CO<sub>2</sub>) AEMS ACDL lidar Doppler shift accuracy |
| url | https://www.mdpi.com/2072-4292/14/18/4620 |
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