Mid-troposphere CO2 data retrieved by the AIRS(atmospheric infrared sounder) were validated with five ground-based stations and aircraft measurements in the Northern Hemisphere.AIRS CO2 products show good agreement with ground and aircraft observations.The data had a monthly average accuracy better than 3 ppmv.In this study,the spatial and temporal distribution of mid-troposphere CO2 from January 2003 to December 2008 was analyzed based on this satellite product.The average concentration of atmospheric CO2 was higher in the Northern Hemisphere than in the Southern Hemisphere.The yearly average results show a gradual increase from 2003 to 2008.In China,the annual growth rate was about 2 ppmv/a,similar to the United States,Europe,Australia and India,but was slightly lower than Canada and Russia.Mid-troposphere CO2 concentrations were higher over northern China than over southern areas,due to differences in natural conditions and industrial layout.There were four centers of high CO2 concentration between 35° and 45°N over China,with low concentrations over Yunnan Province.There was a significant seasonal CO2 variation with peak concentration in spring and the lowest concentration in autumn.
Retrieval experiment was made for global total column ozone using the first year measurements of Total Ozone Unit (TOU) on board the second generation polar orbiting meteorological satellite of China, FY-3/A. The retrieval results were analyzed and validated by comparison with AURA/OMI, Meteop/GOME-2 global ozone products and ground-based ozone measurement data. The qualititative comparisons over the globe especially over Antarctica and the Tibetan Plateau show that the spatial and temporal distribution characteristics are consistent with OMI and GOME-2 products. The quantitative comparisons with ground-based measurements and AURA/OMI ozone product were made over 74 stations, the TOU total ozone retrieval has a 3% rms relative error compared with AURA/OMI ozone product and 4.2% rms relative error with ground-based measurements. The maximum difference between satellite retrieval and ground-based measurements was found in the Antarctica ozone hole. The TOU global ozone product is operational and distributed to all users.
Spaceborne measurements by the Atmospheric Infrared Sounder (AIRS) on the EOS/Aqua satellite provide a global view of methane (CH 4 ) distribution in the mid-upper troposphere (MUT-CH 4 ). The focus of this study is to analyze the spatiotemporal varia- tions in MUT-CH 4 over China from 2003 to 2008. Validation of AIRS CH 4 products versus Fourier transform infrared profiles demonstrates that its RMS error is mostly less than 1.5%. A typical atmospheric methane profile is found that shows how concentrations decrease as height increases because of surface emissions. We found that an important feature in the seasonal variation in CH 4 is the two peaks that exist in summer and winter in most parts of China, which is also observed in in-situ measurements at Mt. Waliguan, Qinghai Province, China (36.2879°N 100.8964°E, 3810 m). Also, in the summer, only one peak existed in western and southern China since there are no more significant anthropogenic sources in winter than at any other time of the year. Further analysis of the deseasonalized time-series of AIRS CH 4 in three fixed pressure layers of AIRS from 2003 to 2008 indicates that CH 4 in the Northern Hemisphere has increased abruptly since 2007, with no significant increase occurring before 2007. The increase in China is generally more significant than in other areas around the world, which again correlates with in-situ measurements at Mt. Waliguan.
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.
