SCIAMACHY Product Handbook
 | |  | The retrieval range is limited at lower altitudes because the atmosphere becomes optically thick with respect to Rayleigh scattering and/or O3 absorption. Above about 40 km the O3 absorption signatures become too weak to be observed. However, normalised limb radiance profiles in the O3 Hartley and Huggins bands can also be used without further wavelength pairing for the derivation of ozone profiles in the upper stratosphere and lower mesosphere (Rohen et al. 2006). The O3 retrievals may be extended up to at least 65 km since the absorption cross sections in the Hartley and Huggins bands are significantly larger than in the Chappuis band. The wide variety of retrieval algorithms currently applied to SCIAMACHY limb and occultation data are summarised in table 5-3, together with their corresponding references. | Parameter | Spectral Window (nm) | Layer | Quantity | Retrieval Algorithm Reference | O3 | 525, 600, 675525-590 | stratosphere | profile | von Savigny et al. 2005 a Doicu et al. 2002, Doicu 2005 | | 240-310 (selected wavelengths) | mesosphere | profile | Rohen et al. 2006 | | 520-595 | stratosphere | profile sun occultation | Meyer et al. 2005 | | 510-560 | stratosphere | profile moon occultation | Amekudzi et al. 2005a | NO2 | 425-450(70) | stratosphere | profile limb | Rozanov et al. 2005 b Sioris et al. 2004 Doicu et al. 2002, Doicu 2005 | | 420-460 | stratosphere | profile sun occultation | Meyer et al. 2005 | | 430-460 | stratosphere | profile moon occultation | Amekudzi et al. 2005a | NO3 | 610-680 | stratosphere | profile moon occultation | Amekudzi et al. 2005b | BrO | 335-360 | stratosphere | profile | Rozanov et al. 2005 b Dorf et al. 2005 | OClO | 365-389 | stratosphere | profile | | NLC | 265-300 | mesosphere | indicator, particle radius | von Savigny et al. 2004a | PSC | 750, 1090 | stratosphere | indicator | von Savigny et al. 2005b | Tmesopause | 1515-1550 | mesosphere | nighttime temperature at mesopause | von Savigny et al. 2004b | | | Table 5-3: Atmospheric geophysical parameters and retrieval algorithms – limb and occultation. | | 5.5 Derivation of Tropospheric Information Of major scientific – and public – interest are distributions of trace gases in the troposphere. Two cases need to be distinguished: | |  | Constituents with the majority of the atmospheric amount residing in the lower troposphere (e.g. CO, CH4, CO2, HCHO, SO2, H2O): The total column derived from UV-VIS and SWIR solar backscatter measurements with the techniques derived in chapter 5.2 directly represents the tropospheric column amount including the boundary layer under cloud free conditions. |  | Trace gases with comparable column amounts in the troposphere and stratosphere (e.g. BrO, NO2) or with the stratospheric amount dominating the total column (e.g. O3): Additional techniques have to be applied to separate tropospheric and stratospheric concentrations. | |  | |  |
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