NineYearsofAtmosphericRemoteSensingwithSCIAMACHY-InstrumentPerformance.ppt

NineYearsofAtmosphericRemoteSensingwithSCIAMACHY-InstrumentPerformance.ppt

• 1.
  Nine Years ofAtmospheric Remote Sensing with SCIAMACHY – Instrument Performance Gottwald, Krieg, Lichtenberg , Slijkhuis – DLR-IMF No ël, Bramstedt, Bovensmann, von Savigny – IUP, Univ. of Bremen Snel, Krijger – SRON
• 2.
  Topics instrument operations instrument status and performance mission extension
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  SCIAMACHY on ENVISAT26 m  10 m  5 m Satellite dimensions 8.2 t Satellite mass 10 No. of instruments 100.6 min Orbit period 10 a.m. (sun-synchronous) Descending node crossing 800 km Mean altitude 98.5° Inclination ENVISAT nominal mission profile
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  Instrument – OpticalAssembly Level 1: channels 1 & 2 (UV) entrance optics calibration unit pre-disperser prism Level 2: channels 3 & 4 (VIS) channel 5 (NIR) channels 6-8 (SWIR)
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  Viewing Geometries scientificnadir limb sun occultation moon occultation calibration & monitoring sun occultation moon occultation subsolar internal calibration lamps (WLS, SLS)
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  Instrument – ThermalSubsystems Optical Bench Module (OBM) cooled via RAD A T = -17.6°C to -18.2°C active thermal control (ATC) detectors cooled via SCIAMACHY Radiant Cooler (SRC) T  195 K – 230 K (channels 1-6) T  140 K – 160 K (channels 7 & 8) open loop heater control (TC) detectors decontamination SRC cooling capacity may degrade because of contamination decontamination heaters to raise T on reflecting surface (if needed) decontamination brings T of OBM and detectors close to 0°C  contaminants are removed
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  Operations instrument operationsare continuous highly autonomous implemented in states and timelines organised in mission scenarios limb/nadir on dayside sun occultation each orbit sub-solar every 3 rd day moon occultation whenever possible dedicated eclipse measurements calibration&monitoring measurements on daily, weekly and monthly timescales
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  instrument operation relatedinformation available via http://atmos.caf.dlr.de/projects/scops/ Instrument Status - Availability launch March 1, 2002 end nominal mission phase March 1, 2007
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  Thermal Systems: ATCand OBM Temperature only small orbital variation of T OBM very stable orbital mean T OBM ATC degradation compensated by heater power adjustment
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  Thermal Systems: TCand Detector Temperatures temperature control via TC heaters TC system degrades detectors 1-6: 0.1-0.3 K / year detectors 7 & 8: approx. 1 K ice layer effect
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  Life Limited Itemsmechanical items (neutral density filter, aperture stop, nadir calibration window) and thermal item (cryogenic heatpipe) have assigned in-flight activation budgets electrical items (WLS, SLS) have assigned in-flight switching budgets operations concept goal is not to exceed LLI limits
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  Optics - Throughputoptical throughput channels 1-6 reduction of 3-4% per year in UV very stable in VIS, NIR & SWIR solar eclipse
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  channels 6+, 7,8: 6% pixel loss / year  about 10-15% ‘good’ pixels by end 2013 in 7 & 8: throughput loss 1-2% / year due to ice layer (decontaminations are still an option to remove ice) Detectors - Degradation channel 2: detector material degradation (2% sensitivity loss / year)  25% loss by end 2013
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  Limb Tangent Heightpointing knowledge essential for geolocation retrieval, particularly limb tangent heights continuos improvement over the mission lifetime: current limb tangent height accuracy about 0.002-0.003° = 120-150 m
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  mission in nominalENVISAT orbit ended 22 October 2010 Mission Extension 2010-2013 since then modified drifting orbit no inclination manoeuvres altitude lowered by 17 km instrument configuration successfully adapted to new orbit SCIAMACHY continues to deliver high quality data
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  SCIAMACHY – Exploringthe Changing Earth’s Atmosphere SCIAMACHY – The Need for Atmospheric Research from Space ENVISAT – SCIAMACHY’s Host The Instrument Instrument Operations Calibration and Monitoring SCIAMACHY In-Orbit Operations and Performance From Radiation Fields to Atmospheric Concentrations – Retrieval of Geophysical Parameters Data Processing and Products Validation SCIAMACHY’s View of the Changing Earth’s Environment