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Status Operations and Dataprocessing

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The GDPS needs attitude and ephemeris data for its ... Differences between 'old' and 'new' attitude and ephemeris data turn out to be very small. ... – PowerPoint PPT presentation

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Title: Status Operations and Dataprocessing


1
Statusof OMI Dataprocessing Jacques Claas
(KNMI)Phil Durbin (Adnet Systems, Inc.)
2
Processing Summary
3
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 has been running in
    forward stream from April 15th 2008 till Oct. 8th
    2008
  • Improvements gt improved wavelength assignment
    gt improved radiance goniometry gt setting noise
    levels for individual pixels gt added float
    field in irradiance product
  • GDPS 1.1.2
  • Running since Oct. 8th 2008
  • Static flagging (XTrackQualityFlags) of CCD rows
    affected by row anomaly

NRT image of tropospheric NO2 over Europe
NRT image of tropospheric NO2 over Beijing
4
Summary of data processing issues
  • FMU anomaly
  • Permanent data loss for 2 orbits 18027 18028
    (Dec 5, 2007).
  • No science data for 9 orbits 18235 18243 (Dec
    19-20, 2007).
  • Operations software anomaly
  • No science data for 51 orbits 22349 22399 (Sep
    27-30, 2008)
  • Row anomaly
  • Two row anomalies exist, affecting part of the
    OMI field of view.
  • Work on correction algorithm in GDPS is on-going.
  • L2 developers must carefully read the L1b readme
    file on the DISC.
  • AURA re-phasing
  • Due to the AURA re-phasing orbits now have
    different geo-location.
  • Current definition of NOSE parameters is not up
    to date. DO NOT USE!

5
Impact of FMU anomaly on data processing (1/3)?
  • 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 -gt 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
Impact of FMU anomaly on data processing (2/3)?
7
Impact of FMU anomaly on data processing (3/3)?
  • Summary
  • The GDPS needs attitude and ephemeris data for
    itsL0 -gt 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).

8
Row anomaly (1/4)?
  • A row anomaly was discovered in September
    2007.This anomaly has persisted since then.
  • On May 19th 2008, a new row anomaly was
    discovered.
  • Both row anomalies impact specific CCD rows (is
    specific part of the OMI field of view).
  • 2007 anomaly 2 rows are affected for complete
    illuminated orbit.
  • 2008 anomaly 4 rows are affected for northern
    part of illuminated orbit.
  • Current tentative explanation is that a small
    piece of MLI has moved into the field of view of
    the nadir port.
  • GDPS
  • The current GDPS 1.1.2 applies static flagging of
    the affected CCD rows in the L1b HDF files
  • A new GDPS version that will use a correction
    algorithm enabling dynamic flagging is under
    development.
  • Data users must carefully read the L1b readme
    file on how to treat the affected CCD rows in
    their retrieval algorithms.

9
Row anomaly (2/4) OMI L0 data
UV image from April 20
X-track
UV image from September 11
wavelength
10
Row anomaly (3/4) impact on L2
11
Row anomaly (4/4) impact on L2
12
Impact of the AURA re-phasing on data processing
(1/2)?
  • 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!). DO
    NOT USE!!
  • Decision - the timing of the monthly spatial
    zoom-in measurements will not be changed, hence
    will keep the changed geo-location.

13
Impact of AURA re-phasing on dataprocessing (2/2)?
Before re-phasing
OMImonthlyspatial zoom-inmeasurements
After re-phasing
De Bilt
Washington
14
PGE to App Transition
  • The OMI SIPS is re-designed to the ACPS
    (Atmospheric Composition Processing System)
  • Instead of developing L2 PGEs for the OMI SIPS,
    scientists must now develop Apps that run on the
    ACPS.
  • Main differences/advantages
  • 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.
  • A 3-6 month OSIPS/PGE -gt ACPS/App transition
    period began in July.SIPS team does conversion
    and training.
  • Existing and older PGE's will still be available
    but source code in CVS will be read only.
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