6. SCIAMACHY in Orbit - The First Years

Fig. 6-1
ENVISAT launch (photo: ESA)
Fig. 6-2
Operations summary for the commissioning and routine operations phase. Colour coding indicates instrument availability.
Fig. 6-3
Calibrated SCIAMACHY solar irradiance spectrum measured April 18th, 2004, in comparison to the Kurucz solar reference spectrum. SCIAMACHY data have been normalised to 1 AU sun distance. Kurucz data have been interpolated to the SCIAMACHY wavelength grid. Top: SCIAMACHY (yellow) and Kurucz (blue) irradiance as function of wavelength with the wavelength coverage of all 8 channels. Bottom: Relative deviation between the two data sets. Small deviations in the wavelength calibration can cause large fluctuations in the ratio of the spectra. Therefore, the deviation is shown as unsmoothed (red) and smoothed (green) curve. The underlying grey bar shows the ±3% requirement for the absolute radiometric calibration of SCIAMACHY which is fulfilled over almost the whole spectral range. (graphics: IUP-IFE, University of Bremen)
Fig. 6-4
Mean OBM temperature per orbit between the start of quasi-routine measurements in early August 2002 to August 2005, almost 3.5 years after launch. On orbit average, the ATC system keeps the OBM within 0.001 °C of the selected temperature. (graphics: DLRIMF)
Fig. 6-5
Power consumption of the 3 heaters (Nadir, Limb and RAD_A) of the ATC system. The curve follows a seasonal variation with an expected long-term decrease most prominent for the ATC_Nadir heater. (graphics: DLR-IMF)
Fig. 6-6
Mean detector temperatures per orbit for channels 1-6. Decontamination intervals with elevated temperatures and periods after instrument safing with too low temperatures are omitted. The resulting curves display the seasonal variation. Steps are due to TC adjustments, mainly affecting channels 4 & 5. The increase around orbit 5000 corresponds to an overall TC correction to establish new temperature ranges. (graphics: DLR-IMF)
Fig. 6-7
Mean detector temperatures per orbit for the SWIR channels 7 & 8. Displayed data are as in fig. 6-6. The graphs are the result of growing ice (increase) and occasional decontaminations (drop to lower values). Between orbit 10600 and 10900 two TC adjustments had a significant impact on the SWIR detectors. (graphics: DLR-IMF)
Fig. 6-8
Optical throughput for channels 1-6. As in fig.6-6, decontamination intervals and periods after instrument safing are omitted. The information has been derived from the operational light path monitoring using the sun via the ASM and ESM mirror. (graphics: DLRIMF and IUP-IFE, University of Bremen)
Fig. 6-9
Optical throughput for the SWIR channels 7 & 8. Similarly to fig. 6-7, a growing ice layer and its decontamination induced evaporation determines the shape of the curve. (graphics: DLR-IMF and IUP-IFE, University of Bremen)
Fig. 6-10
LLI status after more than 3 years of operations. The expected End-of-Life (EOL) values for the specified mission lifetime are all below 100%. In case of a mission extension, as currently discussed, the EOL values will either be higher or the mission scenarios have to be adapted accordingly. (graphics: DLR-IMF)
Fig. 6-11
Tangent height offsets as determined from operational data products and TRUE retrieved profile information. Prior to December 2003 the bias had a strong harmonic variation. After the update of the on-board propagator model this variation is reduced but a constant offset persists. (graphics: DLR-IMF and IUP-IFE, University of Bremen)
Fig. 6-12
Mean light leak signal for all pixels in channel 7 as a function of orbit phase. The x-axis shows the orbit phase (eclipse corresponds to phase 0.95-0.40, sunrise occurs at phase 0.41), the y-axis the pixel number in channel 7. The colours indicate the size of the light leak signal in BU/sec. (graphics: DLR-IMF and SRON)

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