Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 S. Noël IFE/IUP Elevation and Azimuth Jumps during Solar Occultation Measurements (State 47 Analysis)

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 Elevation Jumps

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 SF active SF not yet active mismatch Analysis Description Analysis is based on measurements during pointing phase above atmosphere within solar occultation (State ID 47) Lv0 data have been processed with CFI s/w Mispointing = LOS – PredictedSun = 2 nd last readout) (all angles in SRAR coordinates)

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 Elevation Angle Difference Analysis takes into account: –All known misalignments –Relative timing scanner readouts vs. detector readouts

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 Seasonal Dependencies Some early data have been reprocessed (s/w change); only small change Green: AUX_FRA pitch correction subtracted Seasonal variation remains

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 Summary of Results Results: –Good agreement between predicted and commanded/measured elevation angles before SF use –Position of true sun (as seen by the SF) always at higher altitudes than predicted –Measured signal increases after acquisition of the sun by the SF ðIn compliance with other analysis results the SF is working fine ðSCIAMACHY is looking too low –Average elevation difference 30 – 40 mdeg, scatter about 4 mdeg –Elevation difference shows some seasonal trend –Seasonal trend remains after AUX_FRA pitch correction

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 Azimuth Jumps

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 SF active SF not yet active mismatch Analysis Description Analysis is based on same measurements as for elevation anomaly (State ID 47, BCPS 1055) Difference: SF is used in azimuth earlier (all angles in SRAR coordinates; forward direction = 0/360 deg)

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 Azimuth Angle Difference Analysis takes into account: –All known misalignments –Relative timing scanner readouts vs. detector readouts

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 Seasonal Dependencies Some 2003 data have been reprocessed (s/w change) AUX_FRA correction not considered Shift at orbit ~20000; related to OCM? ?

Institut für Umweltphysik/Fernerkundung Physik/Elektrotechnik Fachbereich 1 Pointing Meeting Nov 2006 Summary of Results Results: –Only slight deviations between predicted and commanded/measured elevation angles before SF use –Azimuth jump of about 0.1 deg after SF switch on (true sun further to the right) –Azimuth difference stays almost constant afterwards (no influence of atmosphere) –If the SF is working fine ðSCIAMACHY is looking too far to the left –Azimuth difference shows some seasonal trend (amplitude ~10 mdeg) –2006 data shifted?