Water vapor retrieval from OMI visible spectra
There are distinct spectral features of water vapor in the wavelength range covered by the Ozone Monitoring Instrument (OMI) visible channel. Although these features are much weaker than those at longer wavelengths, they can be exploited to retrieve useful information about water vapor. They have an...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2014-06-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/7/1901/2014/amt-7-1901-2014.pdf |
| _version_ | 1818595370451599360 |
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| author | H. Wang X. Liu K. Chance G. González Abad C. Chan Miller |
| author_facet | H. Wang X. Liu K. Chance G. González Abad C. Chan Miller |
| author_sort | H. Wang |
| collection | DOAJ |
| description | There are distinct spectral features of water vapor in the wavelength range
covered by the Ozone Monitoring Instrument (OMI) visible channel. Although
these features are much weaker than those at longer wavelengths, they can be
exploited to retrieve useful information about water vapor. They have an
advantage in that their small optical depth leads to fairly simple
interpretation as measurements of the total water vapor column density. We
have used the Smithsonian Astrophysical Observatory (SAO) OMI operational
retrieval algorithm to derive the slant column density (SCD) of water vapor
using the 430–480 nm spectral region after extensive optimization. We
convert from SCD to vertical column density (VCD) using the air mass factor
(AMF), which is calculated using look-up tables of scattering weights and
assimilated water vapor profiles. Our Level 2 product includes not only
water vapor VCD but also the associated scattering weights and AMF. In the
tropics, our standard water vapor product has a median SCD of 1.3 × 10<sup>23</sup> molecules cm<sup>−2</sup> and a median relative uncertainty of about
11%, about a factor of 2 better than that from a similar OMI algorithm
that uses a narrower retrieval window. The corresponding median VCD is about
1.2 × 10<sup>23</sup> molecules cm<sup>−2</sup>. We have examined the
sensitivities of SCD and AMF to various parameters and compared our results
with those from the GlobVapour product, the Moderate Resolution Imaging
Spectroradiometer (MODIS) and the Aerosol Robotic NETwork (AERONET). |
| first_indexed | 2024-12-16T11:14:56Z |
| format | Article |
| id | doaj.art-588da95b125348b98aba92b60428c9ce |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-12-16T11:14:56Z |
| publishDate | 2014-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-588da95b125348b98aba92b60428c9ce2022-12-21T22:33:38ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482014-06-01761901191310.5194/amt-7-1901-2014Water vapor retrieval from OMI visible spectraH. Wang0X. Liu1K. Chance2G. González Abad3C. Chan Miller4Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USAHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USAHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USAHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USADepartment of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USAThere are distinct spectral features of water vapor in the wavelength range covered by the Ozone Monitoring Instrument (OMI) visible channel. Although these features are much weaker than those at longer wavelengths, they can be exploited to retrieve useful information about water vapor. They have an advantage in that their small optical depth leads to fairly simple interpretation as measurements of the total water vapor column density. We have used the Smithsonian Astrophysical Observatory (SAO) OMI operational retrieval algorithm to derive the slant column density (SCD) of water vapor using the 430–480 nm spectral region after extensive optimization. We convert from SCD to vertical column density (VCD) using the air mass factor (AMF), which is calculated using look-up tables of scattering weights and assimilated water vapor profiles. Our Level 2 product includes not only water vapor VCD but also the associated scattering weights and AMF. In the tropics, our standard water vapor product has a median SCD of 1.3 × 10<sup>23</sup> molecules cm<sup>−2</sup> and a median relative uncertainty of about 11%, about a factor of 2 better than that from a similar OMI algorithm that uses a narrower retrieval window. The corresponding median VCD is about 1.2 × 10<sup>23</sup> molecules cm<sup>−2</sup>. We have examined the sensitivities of SCD and AMF to various parameters and compared our results with those from the GlobVapour product, the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic NETwork (AERONET).http://www.atmos-meas-tech.net/7/1901/2014/amt-7-1901-2014.pdf |
| spellingShingle | H. Wang X. Liu K. Chance G. González Abad C. Chan Miller Water vapor retrieval from OMI visible spectra Atmospheric Measurement Techniques |
| title | Water vapor retrieval from OMI visible spectra |
| title_full | Water vapor retrieval from OMI visible spectra |
| title_fullStr | Water vapor retrieval from OMI visible spectra |
| title_full_unstemmed | Water vapor retrieval from OMI visible spectra |
| title_short | Water vapor retrieval from OMI visible spectra |
| title_sort | water vapor retrieval from omi visible spectra |
| url | http://www.atmos-meas-tech.net/7/1901/2014/amt-7-1901-2014.pdf |
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