A large number of experimental and theoretical investigations of carbon dioxide （CO 2 ） spectra have been conducted since the most recent update of the High-Resolution Transmission Molecular Absorption （HITRAN） da...A large number of experimental and theoretical investigations of carbon dioxide （CO 2 ） spectra have been conducted since the most recent update of the High-Resolution Transmission Molecular Absorption （HITRAN） database. To maintain optimal parameters, the HITRAN 2004 CO 2 line list has been completely replaced by HITRAN 2008 data in the near-infrared region from 4300 cm-1 to 7000 cm-1 . To examine the effect of this change on the retrieval of CO 2 vertical column data from reflected sunlight spectra in the 1.61-μm spectral window, synthetic measurements for a given atmospheric state and instrument setup were generated and compared using radiative transfer model with the line-transition parameters from the HITRAN 2004 and 2008 databases. Simulated retrievals were then performed based on the optimal estimation retrieval theory. The results show that large systematic errors in atmospheric CO 2 column retrievals were induced by the differences in the HITRAN laboratory line parameters in the 1.61-μm region. The retrieved CO 2 columns were underestimated by 10 ppm using the HITRAN 2004 data, and improvements resulting from the use of the improved HITRAN database were more pronounced at a higher spectral resolution.展开更多
The line-transition parameters of the High Resolution Transmission （HITRAN） 2008 database have been updated relative to previous editions. The transmission spectra and sensitivity to changes in CO2 concentrations us...The line-transition parameters of the High Resolution Transmission （HITRAN） 2008 database have been updated relative to previous editions. The transmission spectra and sensitivity to changes in CO2 concentrations using line parameters from the HITRAN 2004 and HITRAN 2008 databases are compared to evaluate the effect of the database updates on retrievals of carbon dioxide vertical columns from nearinfrared reflected sunlight. This comparison is done in three spectral regions covering the 2.06-, 1.61-, and 1.58-μm CO2 bands used by the Greenhouse Gases Observatory Satellite （GOSAT） instrument and the planned successor to the Orbiting Carbon Observatory （OCO）. The updates to the HITRAN database have the largest effects on the transmittance and the off-line to on-line transmittance ratio in the 2.06-μm region and the smallest effects on these parameters in the 1.58-μm region. The influence of the updates to the HITRAN database on the off-line to on-line ratio calculation in the narrow spectral region 4855-4880 cm^-1 could be equivalent to a change in CO2 of more than 50 ppmv. Use of the HITRAN 2004 database will lead to an underestimate of the column CO2 abundance in the 2.06- and 1.61-pro spectral regions, whereas it will lead to an overestimate of the column CO2 abundance in the 1.58-μm spectral region.展开更多
基金supported by the National Natural Science Foundation of China (Grant No 41130104)Ministry of Science and Technology of China (Grant No 2010DFA22770)+1 种基金the key projects fromthe 11th Five-Year Plan of national scientific and technological (Grant No 2008BAC34B04-2)the National Basic Research Program of China (also called 973 Program,Grant Nos 2005CB422200x and 2006CB403702)
文摘A large number of experimental and theoretical investigations of carbon dioxide （CO 2 ） spectra have been conducted since the most recent update of the High-Resolution Transmission Molecular Absorption （HITRAN） database. To maintain optimal parameters, the HITRAN 2004 CO 2 line list has been completely replaced by HITRAN 2008 data in the near-infrared region from 4300 cm-1 to 7000 cm-1 . To examine the effect of this change on the retrieval of CO 2 vertical column data from reflected sunlight spectra in the 1.61-μm spectral window, synthetic measurements for a given atmospheric state and instrument setup were generated and compared using radiative transfer model with the line-transition parameters from the HITRAN 2004 and 2008 databases. Simulated retrievals were then performed based on the optimal estimation retrieval theory. The results show that large systematic errors in atmospheric CO 2 column retrievals were induced by the differences in the HITRAN laboratory line parameters in the 1.61-μm region. The retrieved CO 2 columns were underestimated by 10 ppm using the HITRAN 2004 data, and improvements resulting from the use of the improved HITRAN database were more pronounced at a higher spectral resolution.
基金Supported by the National Natural Science Fundation of China (41130104 and 40905056)Ministry of Science and Technology of China (2010DFA22770 and GYHY201106045)
文摘The line-transition parameters of the High Resolution Transmission （HITRAN） 2008 database have been updated relative to previous editions. The transmission spectra and sensitivity to changes in CO2 concentrations using line parameters from the HITRAN 2004 and HITRAN 2008 databases are compared to evaluate the effect of the database updates on retrievals of carbon dioxide vertical columns from nearinfrared reflected sunlight. This comparison is done in three spectral regions covering the 2.06-, 1.61-, and 1.58-μm CO2 bands used by the Greenhouse Gases Observatory Satellite （GOSAT） instrument and the planned successor to the Orbiting Carbon Observatory （OCO）. The updates to the HITRAN database have the largest effects on the transmittance and the off-line to on-line transmittance ratio in the 2.06-μm region and the smallest effects on these parameters in the 1.58-μm region. The influence of the updates to the HITRAN database on the off-line to on-line ratio calculation in the narrow spectral region 4855-4880 cm^-1 could be equivalent to a change in CO2 of more than 50 ppmv. Use of the HITRAN 2004 database will lead to an underestimate of the column CO2 abundance in the 2.06- and 1.61-pro spectral regions, whereas it will lead to an overestimate of the column CO2 abundance in the 1.58-μm spectral region.
