Comparison of Three High Resolution Real-Time Spectrometers for Microwave Ozone Profiling Instruments
In this contribution, we present a comparison of three digital real-time spectrometers used in passive remote sensing of ozone and other trace gases in the middle atmosphere. During a period of six months, we connected the spectrometers to the same radiometric front-end to perform parallel observati...
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| Format: | Article |
| Language: | English |
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IEEE
2021-01-01
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| Series: | IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/9546538/ |
| _version_ | 1818936665217957888 |
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| author | Eric Sauvageat Roland Albers Mikko Kotiranta Klemens Hocke Richard Gomez Gerald Nedoluha Axel Murk |
| author_facet | Eric Sauvageat Roland Albers Mikko Kotiranta Klemens Hocke Richard Gomez Gerald Nedoluha Axel Murk |
| author_sort | Eric Sauvageat |
| collection | DOAJ |
| description | In this contribution, we present a comparison of three digital real-time spectrometers used in passive remote sensing of ozone and other trace gases in the middle atmosphere. During a period of six months, we connected the spectrometers to the same radiometric front-end to perform parallel observations of the ozone emission line at 110.836 GHz. This allowed us to better characterize a bias previously observed on the integrated spectra of the Acqiris AC240, a widely used digital spectrometer which has been used for more than a decade in many operational microwave radiometers. We investigated the bias under different atmospheric conditions and found that it is caused by multiple sources. Nonlinearities in the calibration are responsible for part of the bias, but a larger contribution stems from a second effect in the AC240. Although this error source is still partly unexplained, we found that a simple correction scheme simulating a spectral leakage can be applied to the integrated spectra of the AC240 and worked well on our range of observations. We also show that by applying our bias correction to the spectra, we can correct the bias in the ozone retrievals. There is still a need for further measurements to validate this approximate correction, but it could help to correct the numerous time series of ozone and other atmospheric constituents recorded by the AC240. |
| first_indexed | 2024-12-20T05:39:40Z |
| format | Article |
| id | doaj.art-c57114dc59e640b2b45c9954682e4c46 |
| institution | Directory Open Access Journal |
| issn | 2151-1535 |
| language | English |
| last_indexed | 2024-12-20T05:39:40Z |
| publishDate | 2021-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing |
| spelling | doaj.art-c57114dc59e640b2b45c9954682e4c462022-12-21T19:51:30ZengIEEEIEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing2151-15352021-01-0114100451005610.1109/JSTARS.2021.31144469546538Comparison of Three High Resolution Real-Time Spectrometers for Microwave Ozone Profiling InstrumentsEric Sauvageat0https://orcid.org/0000-0002-9610-4503Roland Albers1https://orcid.org/0000-0002-8537-2844Mikko Kotiranta2https://orcid.org/0000-0003-3731-5623Klemens Hocke3https://orcid.org/0000-0003-2178-9920Richard Gomez4Gerald Nedoluha5https://orcid.org/0000-0002-9853-6262Axel Murk6https://orcid.org/0000-0003-2949-844XInstitute of Applied Physics and the Oeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandInstitute of Applied Physics, University of Bern, Bern, SwitzerlandInstitute of Applied Physics, University of Bern, Bern, SwitzerlandInstitute of Applied Physics and the Oeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandRemote Sensing Division, U.S. Naval Research Laboratory, Washington, DC, USARemote Sensing Division, U.S. Naval Research Laboratory, Washington, DC, USAInstitute of Applied Physics and the Oeschger Centre for Climate Change Research, University of Bern, Bern, SwitzerlandIn this contribution, we present a comparison of three digital real-time spectrometers used in passive remote sensing of ozone and other trace gases in the middle atmosphere. During a period of six months, we connected the spectrometers to the same radiometric front-end to perform parallel observations of the ozone emission line at 110.836 GHz. This allowed us to better characterize a bias previously observed on the integrated spectra of the Acqiris AC240, a widely used digital spectrometer which has been used for more than a decade in many operational microwave radiometers. We investigated the bias under different atmospheric conditions and found that it is caused by multiple sources. Nonlinearities in the calibration are responsible for part of the bias, but a larger contribution stems from a second effect in the AC240. Although this error source is still partly unexplained, we found that a simple correction scheme simulating a spectral leakage can be applied to the integrated spectra of the AC240 and worked well on our range of observations. We also show that by applying our bias correction to the spectra, we can correct the bias in the ozone retrievals. There is still a need for further measurements to validate this approximate correction, but it could help to correct the numerous time series of ozone and other atmospheric constituents recorded by the AC240.https://ieeexplore.ieee.org/document/9546538/Atmospheric measurementsdigital real-time spectrometersmicrowave radiometrymicrowave spectroscopyozoneremote sensing |
| spellingShingle | Eric Sauvageat Roland Albers Mikko Kotiranta Klemens Hocke Richard Gomez Gerald Nedoluha Axel Murk Comparison of Three High Resolution Real-Time Spectrometers for Microwave Ozone Profiling Instruments IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing Atmospheric measurements digital real-time spectrometers microwave radiometry microwave spectroscopy ozone remote sensing |
| title | Comparison of Three High Resolution Real-Time Spectrometers for Microwave Ozone Profiling Instruments |
| title_full | Comparison of Three High Resolution Real-Time Spectrometers for Microwave Ozone Profiling Instruments |
| title_fullStr | Comparison of Three High Resolution Real-Time Spectrometers for Microwave Ozone Profiling Instruments |
| title_full_unstemmed | Comparison of Three High Resolution Real-Time Spectrometers for Microwave Ozone Profiling Instruments |
| title_short | Comparison of Three High Resolution Real-Time Spectrometers for Microwave Ozone Profiling Instruments |
| title_sort | comparison of three high resolution real time spectrometers for microwave ozone profiling instruments |
| topic | Atmospheric measurements digital real-time spectrometers microwave radiometry microwave spectroscopy ozone remote sensing |
| url | https://ieeexplore.ieee.org/document/9546538/ |
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