Analysis of ACAM Data for Trace Gas Retrievals during the 2011 DISCOVER-AQ Campaign
To improve the trace gas retrieval from Airborne Compact Atmospheric Mapper (ACAM) during the DSICOVER-AQ campaigns, we characterize the signal to noise ratio (SNR) of the ACAM measurement. From the standard deviations of the fitting residuals, the SNRs of ACAM nadir measurements are estimated to va...
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| Format: | Article |
| Language: | English |
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Wiley
2015-01-01
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| Series: | Journal of Spectroscopy |
| Online Access: | http://dx.doi.org/10.1155/2015/827160 |
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| author | C. Liu X. Liu M. G. Kowalewski S. J. Janz G. González Abad K. E. Pickering K. Chance L. N. Lamsal |
| author_facet | C. Liu X. Liu M. G. Kowalewski S. J. Janz G. González Abad K. E. Pickering K. Chance L. N. Lamsal |
| author_sort | C. Liu |
| collection | DOAJ |
| description | To improve the trace gas retrieval from Airborne Compact Atmospheric Mapper (ACAM) during the DSICOVER-AQ campaigns, we characterize the signal to noise ratio (SNR) of the ACAM measurement. From the standard deviations of the fitting residuals, the SNRs of ACAM nadir measurements are estimated to vary from ~300 at 310 nm to ~1000 in the blue spectral region; the zenith data are noisier due to reduced levels of illumination and lower system throughput and also show many more pixels with abrupt anomalous values; therefore, a new method is developed to derive a solar irradiance reference at the top of the atmosphere (TOA) from average nadir measurements, at instrument spectral resolution and including instrument calibration characteristics. Using this reference can significantly reduce fitting residuals and improve the retrievals. This approach derives an absolute reference for direct fitting algorithms involving radiative transfer calculations and thus can be applied to both aircraft and ground-based measurements. The comparison of ACAM radiance with simulations using coincident ozonesonde and OMI data shows large wavelength-dependent biases in ACAM data, varying from ~−19% at 310 nm to 5% at 360 nm. Correcting ACAM radiance in direct-fitting based ozone profile algorithm significantly improves the consistency with OMI total ozone. |
| format | Article |
| id | doaj-art-a370393f7f044382997391d3b6863bc9 |
| institution | Kabale University |
| issn | 2314-4920 2314-4939 |
| language | English |
| publishDate | 2015-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Journal of Spectroscopy |
| spelling | doaj-art-a370393f7f044382997391d3b6863bc92025-02-03T01:10:05ZengWileyJournal of Spectroscopy2314-49202314-49392015-01-01201510.1155/2015/827160827160Analysis of ACAM Data for Trace Gas Retrievals during the 2011 DISCOVER-AQ CampaignC. Liu0X. Liu1M. G. Kowalewski2S. J. Janz3G. González Abad4K. E. Pickering5K. Chance6L. N. Lamsal7Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USAHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USAGoddard Earth Sciences Technology and Research, Universities Space Research Association, Columbia, MD 21044, USANASA Goddard Space and Flight Center, Greenbelt, MD 20771, USAHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USANASA Goddard Space and Flight Center, Greenbelt, MD 20771, USAHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USAGoddard Earth Sciences Technology and Research, Universities Space Research Association, Columbia, MD 21044, USATo improve the trace gas retrieval from Airborne Compact Atmospheric Mapper (ACAM) during the DSICOVER-AQ campaigns, we characterize the signal to noise ratio (SNR) of the ACAM measurement. From the standard deviations of the fitting residuals, the SNRs of ACAM nadir measurements are estimated to vary from ~300 at 310 nm to ~1000 in the blue spectral region; the zenith data are noisier due to reduced levels of illumination and lower system throughput and also show many more pixels with abrupt anomalous values; therefore, a new method is developed to derive a solar irradiance reference at the top of the atmosphere (TOA) from average nadir measurements, at instrument spectral resolution and including instrument calibration characteristics. Using this reference can significantly reduce fitting residuals and improve the retrievals. This approach derives an absolute reference for direct fitting algorithms involving radiative transfer calculations and thus can be applied to both aircraft and ground-based measurements. The comparison of ACAM radiance with simulations using coincident ozonesonde and OMI data shows large wavelength-dependent biases in ACAM data, varying from ~−19% at 310 nm to 5% at 360 nm. Correcting ACAM radiance in direct-fitting based ozone profile algorithm significantly improves the consistency with OMI total ozone.http://dx.doi.org/10.1155/2015/827160 |
| spellingShingle | C. Liu X. Liu M. G. Kowalewski S. J. Janz G. González Abad K. E. Pickering K. Chance L. N. Lamsal Analysis of ACAM Data for Trace Gas Retrievals during the 2011 DISCOVER-AQ Campaign Journal of Spectroscopy |
| title | Analysis of ACAM Data for Trace Gas Retrievals during the 2011 DISCOVER-AQ Campaign |
| title_full | Analysis of ACAM Data for Trace Gas Retrievals during the 2011 DISCOVER-AQ Campaign |
| title_fullStr | Analysis of ACAM Data for Trace Gas Retrievals during the 2011 DISCOVER-AQ Campaign |
| title_full_unstemmed | Analysis of ACAM Data for Trace Gas Retrievals during the 2011 DISCOVER-AQ Campaign |
| title_short | Analysis of ACAM Data for Trace Gas Retrievals during the 2011 DISCOVER-AQ Campaign |
| title_sort | analysis of acam data for trace gas retrievals during the 2011 discover aq campaign |
| url | http://dx.doi.org/10.1155/2015/827160 |
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