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Science Data Segment


4-Mirror Anastigmat. All Reflective. Aft Optics Imager. 3-Mirror Anastigmat. All reflective. Rotating telescope. FPIE. Solar Diffuser. Blackbody ... – PowerPoint PPT presentation

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Title: Science Data Segment

The NPOESS Preparatory Project NPP OSU MODIS
Workshop September 4 , 2003
Dr. Wayne Esaias NASA GSFC
What is NPP?
  • NPP is the NPOESS Preparatory Project
  • NPP is a bridging mission that provides for the
    continuation of measurement series initiated with
    EOS Terra Aqua for NASAs global change
  • Climate change
  • Global carbon cycle
  • Global water cycle
  • NPP provides risk reduction for the National
    Polar-Orbiting Operational Environmental
    Satellite System (NPOESS) which will continue
    these measurements into the indefinite future
  • NPP is a joint program of NASA and the Integrated
    Program Office (IPO), the tri-agency activity
    that is responsible for NPOESS
  • NPP will launch in the fall of 2006

What is the NPOES Mission?
  • Mission
  • Provide a national, operational, polar-orbiting
    environmental capability
  • Achieve National Performance Review savings by
    converging DoD and NOAA polar satellite programs
  • Incorporate new technologies from NASA and others
  • Incorporate, where appropriate, International
    Cooperation (EUMETSAT)

NPP Sensors
  • The Visible Infrared Imaging Spectroradiometer
    Suite (VIIRS) extends measurement series
    initiated by MODIS on EOS Terra Aqua
  • Design is evolutionary from MODIS
  • The Cross-track Infrared Sounder (CrIS) continues
    measurement series initiated by AIRS on EOS Aqua
  • Utilizes a Michelson interferometer in contrast
    to AIRS, which is a spectrometer
  • The Advanced Technology Microwave Sounder (ATMS)
    continues the measurement series initiated by the
    AMSU on NOAA-15
  • MMIC Technology used to reduce mass, power
  • The Ozone Mapping and Profiling Suite (OMPS)
    continues the measurement series of SBUV TOMS
    and adds a new limb profiler
  • The Clouds and Earth Radiant Energy Sensor
    (CERES) may be added to the payload to continue
    the radiation budget data record initiated by
    ERBE and continued by CERES on Terra and Aqua
  • Decision in late 2003

  • NPP has 824 km Sun synchronous orbit
  • 1030 AM descending node
  • 98.74 inclination
  • Mimics Terra ground track repeat
  • 16 day ground-track repeat
  • Swath width of 3,000 Km (56.06)
  • NPOESS has 833 km Sun synchronous orbits
  • All 3 satellites will carry a VIIRS
  • 0930 descending node
  • 1330 ascending node
  • 1730 ascending node
  • Swath width of 3,000 km (56.06)

Visible Infrared Imaging Radiometer Suite (VIIRS)
  • Purpose Global observations of land, ocean,
    atmosphere parameters at high temporal resolution
    ( daily)
  • Predecessor Instruments AVHRR, OLS, MODIS,
  • Management Integrated Program Office
  • StatusPhase C/D (Raytheon)
  • Approach Multi-spectral scanning radiometer (22
    bands between 0.4 ?m and 12 ?m) 12-bit
  • Swath width 3000 km
  • Changes to specifics of band dynamic ranges,
    bandpasses band centers negotiated
  • Consideration of adding 6.7 micrometer water
    vapor band to FM3 later models
  • CDR Completed March 2002

VIIRS Spectral Bands
  • 22 Bands
  • Subset of MODIS bands plus day-night panchromatic
  • Two spatial resolutions
  • Imagery resolution bands 370 m at nadir
  • Moderate resolution bands 740 m at nadir
  • Features
  • 8 (Moderate) or 16 (Imagery) detectors per scan
  • Bands spatially nested
  • Some bands have dual gain
  • Maximize dynamic range without precision
  • Constrained pixel growth with scan angle

Detector Aggregation Reduces Pixel Growth
to 1060km
VIIRS Reduces Pixel Size Along Scan Much Better
HSR, SNR Toward Nadir
AVHRR MODIS 1 km Bands 2x6km At
Edge Vs. VIIRS 1.6x1.6 km At Edge
Horizontal Sampling Interval
to 1060km
Horizontal Sampling Interval
Moderate and Imaging bands nest 2x2
Reduced Pixel Growth Along Scan
Ratio of Off-nadir pixel to nadir pixel
1500 km
Dual Gain Bands Meet Ocean Land Needs
412 nm Band
Low Gain a 1.1628E-04 b 1.6177E-02
High Gain a 1.1628E-04 b 3.4392E-03
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  • Stray light much better than MODIS
  • Driven by needs of the day-night (DNB)
  • Rotating telescope, extensive baffling reduces
    scattered light
  • V-grove blackbody similar to MODIS
  • Baffled to avoid Earth illumination
  • Emissivity of 0.9998
  • Controlled to 290K by pulsed voltage
  • Heat to 315K
  • Solar Diffuser (SD) evolutionary from MODIS
  • 1 time door
  • New design eliminates ripples
  • Solar Diffuser Stability Monitor (SDSM)
    evolutionary from MODIS
  • 7 bands
  • Views 70 of SD area
  • Planning to use 2nd order polynomial for all
  • Characterization plan similar to MODIS
  • Lunar views possible thru space-view port

VIIRS Status
  • Critical Design Review was held in March 2002
  • Algorithms delivered from Raytheon to Northrop
    Grumman Space Technologies (NGST) in Fall of 2002
  • Further algorithm testing by NGST until late 2004
  • Sequential release of algorithms to Raytheon
    Aurora for conversion to operational code
  • SST delivered March 31, 2003
  • Ocean color to be delivered April 30, 2003
  • Some additional algorithm work possible after
    delivery for operationalization
  • Problem with VIIRS optical design discovered in
    October 2002
  • Detectors see inside of rotating telescope which
    varies in temperature
  • 3 design options examined by Red Team in December
  • Design fix identified
  • Optics will be reduced from f/6.0 to f/6.2
    resulting in small performance degradation
  • CDR on new design May 8, 2003
  • No slip in delivery schedule

NRA Status
  • Approximately 70 proposals were received in
    response to the NPP NRA
  • The team will assist NASA in preparing to use the
    operational system for long term climate research
  • Which EDRs can be used as CDRs?
  • What steps need to be taken to assure climate
    quality data?
  • Use simulations based on real and synthetic data
  • Provide insight into sensor characterization
  • Selection of team planned for summer 2003
  • A second science team selection will be made
    closer to the launch of NPP
  • NASA HQ working on plans for discipline-based
    themes to produce Climate Data Records

Some Web Sites
  • A description of the NPP mission may be found at
  • http//
  • The VIIRS instrument is described at
  • http//
  • The VIIRS ATBDs are at
  • http//
  • The complete list of NPOESS requirements may be
    obtained at
  • http//

  • MODIS quality measurements will be continued in
    the operational system (NPOESS)
  • VIIRS draws heavily on its MODIS heritage
  • Some research capabilities (e.g. fluorescence,
    CO2 slicing bands) are not continued
  • Overall similar radiometric quality
  • Improved geometric resolution
  • Continued commitment to characterization and
  • NASA science team to be competed soon

Visible Infrared Imaging Spectroradiometer (VIIRS)
Yields Lower Scattered Light than MODIS
VIIRS 0ptimized Bandset Provides Rich Data for
All EDRs
Ocean Color/Chlorophyll EDR - RDR Data Summary
Performance Summary for Low-gain State of
Dual-gain Bands
Performance Summary for Single Gain or High Gain