Robert Wolfe NASA Goddard Space Flight Center

1
MODIS (and VIIRS Land) Current and Future use
of HDF

• Robert WolfeNASA Goddard Space Flight Center
• Code 614.5, Greenbelt, MDrobert.e.wolfe_at_nasa.gov

2
Terra and Aqua MODIS

• 3 Nadir Spatial Resolutions
• 250m (1,2), 500m (3-7), and 1km (8-36)
• 4 Focal Plane Assemblies (FPAs)
• VIS, NIR, SMIR, and LWIR
• 36 Spectral Bands
• Reflective solar bands (1-19, and 26), thermal
  emissive bands (20-25, 27-36)
• On-Board Calibrators (OBCs)
• Solar diffuser (SD)
• SD stability monitor (SDSM)
• Blackbody (BB)
• Spectro-radiometric calibration assembly (SRCA)
• Space view (SV)
• Science Applications
• Land, oceans, and atmosphere
• Nearly 40 science products generated and
  distributed

Terra (EOS-AM) Launched Dec.1999 First light Feb.
2000
Aqua (EOS-PM) Launched May 2002 First light June
2002
Page 2
3
Current MODIS HDF Usage

• MODIS Level 1 (L1), Atmosphere and Land product
  formats are
• HDF4
• HDF4-EOS structural metadata (swath and grid)
• ECS core metadata (ODL string)
• Mostly SDSs and Attributes (some VDATA)
• Internal compression
• Geolocation stored in swath products both
  internally (reduced resolution) and externally
  (full resolution)
• MODIS Oceans (SeaWiFS heritage) product formats
  are
• HDF4
• ECS core equivalent metadata stored as
  attributes (matches SeaWifs format)
• Mostly SDSs and Attributes (some VDATA for L3
  intermediate products)
• External compression (i.e. gzip)

3
4
MODIS HDF4 Commentary

• Commentary my views, not official MODIS views
• Simple HDF Attributes should have been used for
  both HDF-EOS structural metadata and ECS core
  metadata
• If attributes had been used then
• It would have been easier for users to read
  metadata fields using the standard HDF library
  (without SDP library)
• It would have made it easier for Science Team
  developers to read/write metadata
• Some lessons learned for Terra (and Aqua) were
  applied to the Aura mission data formats

4
5
Planned MODIS HDF Usage

• MODIS will (likely) provide products in HDF5 in
  2011 timeframe
• L1, Land, Atmosphere
• Initially, HDF5 will be offered as one format
  available as a Post-processing option (i.e. like
  GeoTIFF) for MODIS Collection 6 products
• MODIS Collection 6 reprocessing will start early
  2010 and be completed by end of 2010
• HDF5-EOS structural metadata
• ECS core metadata fields are likely to be stored
  as simple HDF5 attributes
• Internal compression will be used
• Later, PGEs (science software) I/O may be
  rewritten to read/write HDF5
• Oceans
• Switch to HDF5 will be driven by user community
• HDF5 will be used for Aquarius (produced by
  SeaWiFS group)
• SeaDAS user tool will be modified to read/write
  HDF5 as well as HDF4

5
6
VIIRS Land Bands
7
VIIRS Visible, NIR and SWIR Bands

• bbb
• ccc

8
Current VIIRS Land PEATE HDF Usage

• VIIRS Land PEATE converts NOAA IDPS provided
  products from HDF5 to HDF4 to be compatible with
  MODIS
• Aggregates data to L1/L2 data to 5 min. granules
• Simple HDF attributes used for metadata
• All VIIRS Science Data Record (SDR, L1) and EDR
  Environmental Data Record (EDR, L2/3) software
  have been converted to run with HDF4 data
• I/O wrapper is used in algorithms
• DDR (Diagnostic Data Record, L2/3) software
  reads/writes HDF4
• NASA Direct Broadcast (DB) Laboratory is
  modifying I/O wrapper to read/write standard IDPS
  HDF5 products to support DB community

8
9
VIIRS HDF5 Commentary

• Commentary my views, not official Land PEATE
  views
• HDF5 implementation by IDPS has several major
  flaws
• Complex data structures were developed to support
  aggregation by time and by products
• Simple HDF5 features (dimensions, units, etc.)
  are not being used instead these fields are
  stored as HDF attributes
• Un-aggregated granules are much shorter than 5
  minutes (1 minute) so they are many (many) files
  to deal with
• For SDRs, each band is stored separately, unless
  specifically ordered as band aggregates by users

9
10
Planned VIIRS Land PEATE HDF Usage

• Note The VIIRS Land PEATE is funded to help the
  NASA science team to evaluate the VIIRS SDR and
  Land EDR products, not to distribute them (or the
  DDRs) to the general science community
• There will likely be a convergence MODIS/VIIRS
  SDR and Land EDR HDF5 product formats
• A rational HDF5-EOS format will be used (see
  earlier MODIS Land HDF5 discussion)
• MODIS HDF4/5 converter will be modified to also
  work with VIIRS
• Likely to be available in the early VIIRS
  post-launch timeframe (mid-2011)
• This will only be available to the general
  science community if NASA policy changes

10
11
Planned VIIRS Ocean PEATE HDF Usage

• Note The VIIRS Ocean PEATE is funded to help
  the NASA science team to evaluate the VIIRS SDR
  and Land EDR products, not to distribute them (or
  the DDRs) to the general science community
• If the NASA policy changes, there will likely be
  a convergence MODIS/VIIRS Ocean EDR HDF5
  product formats produced by the VIIRS Ocean PEATE
  (see earlier MODIS Ocean HDF5 discussion)

11
12
MODIS/Aqua Haze over China and KoreaOct. 28, 2009
13
Thank you!