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Status of OMI Operations and Dataprocessing

Status of OMI Operations and Dataprocessing Jacques Claas (KNMI) Phil Durbin (Adnet Systems, Inc.). Instrument status. Nominal Operations Baseline has not changed. CCD temperatures are very stable. The thermal settings for CCD and OPB still have their initial values.

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Status of OMI Operations and Dataprocessing

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  1. Statusof OMI OperationsandDataprocessing Jacques Claas (KNMI)Phil Durbin (Adnet Systems, Inc.)

  2. Instrument status • Nominal Operations Baseline has not changed. • CCD temperatures are very stable. • The thermal settings for CCD and OPB still have their initial values. • The life limited items (calibration source and mechanisms) are far within budget. • There have been no mechanism anomalies. • Fully operational for more than 99.9% over the last year. OMI flight model

  3. Instrument topics • Two calibration dark measurements have been updated to account for the degradation of the CCD:- Dark measurements have longer duration (120 sec instead of 20 sec)- Solar dark measurements have a longer duration (256 sec instead of 164 sec) • All measurements for which the instrument mechanisms are used have been updated. Mechanisms are operated differently to avoid bouncing against the end stop of the mechanisms. • A special measurement has been developed switching on the White Light Source (WLS) for a long time: 14 minutes. Purpose is to increase the WLS output (inner bulb surface gets contaminated by the tungsten from the filament). • The instrument’s performance is affected by two CCD row anomalies (for details see presentation Marcel Dobber)Special measurements have been/will be performed to support the analysis of the row anomalies. AURA in fairing

  4. Instrument topics cntd. Increasing the WLS output by performing special “WLS long” measurements

  5. Spacecraft topics: FMU anomaly • Formatting Multiplexer Unit: electronics for writing to / reading from the Solid State Recorder. • A FMU anomaly started on Dec 4th 2007 corrupting the SSR partition 6 data containing S/C housekeeping data and MLS plus HIRDLS science data. • The anomaly is most likely caused by a memory chip. The FMU behaviour was erratic at the time of the anomaly. • The GBAD data that OSIPS needs for its L0 -> L1B processing is derived from the S/C housekeeping data (attitude/ephemeris). Due to the anomaly no data processing was possible. • There has been no loss of OMI science data due to the anomaly. But on Dec 19th no measurements could be performed for 8 orbits (18235 – 18242). • Since Dec 19th 2007 for unexplained reasons, no anomalies have been observed in the GBAD data and HIRDLS data. MLS misses only 2-10 science packets a day. • In case the FMU anomaly shows up again, either a FMU reset or a FMU swap from the S/C A to the B-side will be performed. Based on a risk assessment procedures for this have been developed.

  6. Spacecraft topics: the AURA re-phasing • On NASA instigation, between Dec 5th 2007 and May 8th 2008, a relocation of the AURA satellite was performed. • Purpose: - Improving the science output by combining AQUA and AURA science data (overlapping fields of view for particular instruments, smaller time difference). - distance before: 5918 km, distance after: 3674 km • Consequence: - the OMI groundtrack has moved about 120 km eastwards (about 6 groundpixels). - the OMI monthly spatial zoom-in measurements now have a different geo-location. - the NOSE parameters have to be updated (not done yet!). • Decision: - the timing of the monthly spatial zoom-in measurements will not be changed, hence will keep the changed geo-location.

  7. Spacecraft topics: the AURA re-phasing Before re-phasing OMImonthlyspatial zoom-inmeasurements After re-phasing De Bilt Washington

  8. Data processing status • Collection 3:THE dataset for L1B and L2 products. Data are available on the DISC. Do NOT use older data. • The L1b forward stream as well as the L2 NRT stream are very stable • NRT data available within three hours after the overpass • GDPS 1.1.1.1: • the new GDPS version 1.1.1.1 is running in forward stream since April 15th 2008 • improvements: > improved wavelength assignment > improved radiance goniometry > setting noise levels for individual pixels > added float field in irradiance product NRT image of tropospheric NO2 over Europe NRT image of tropospheric NO2 over Beijing

  9. Data processing topics • Due to S/C issues there was permanent data loss for 2 orbits:18027 – 18028 (Dec 5, 2007). • Due to S/C issues no science data were taken for 9 orbits:18235 – 18243 (Dec 19-20, 2007). • Row anomaly: L2 developers must carefully read the L1b readme file on the DISC. • Impact of the spacecraft FMU anomaly: • The GDPS needs attitude and ephemeris data for its L0 -> L1b processing in order to determine the geo-location of ground pixels. • Until the FMU anomaly, attitude and ephemeris data were based on GBAD data • Since the FMU anomaly, attitude and ephemeris data are based on the OMI specific APID 1836/1837 data. • Differences between “old” and “new” attitude and ephemeris data turn out to be very small. Differences in geo-location are less than 1% of the ground pixel size (see KNMI Technical Note 908).

  10. Processing Summary

  11. PGE to App Transition • An App is similar to PGE and also runs in the SIPS. • Can be run directly from TLCF or user workstations. • Quicker delivery mechanism because it uses automatic checking of the App structure. • Uses subversion (svn) instead of CVS as a code repository. • Schedule 3-6 month transition period beginning in July although some PGE's have already been converted. SIPS team does conversion and training. • Existing and older PGE's will still be available but source code in CVS will be read only.

  12. Backup slides

  13. Impact of FMU anomaly on data processing

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