Published on February 17, 2014
MODIS (and VIIRS Land) Current and Future use of HDF Robert Wolfe NASA Goddard Space Flight Center Code 614.5, Greenbelt, MD firstname.lastname@example.org
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) • Terra (EOS-AM) Aqua (EOS-PM) Launched Dec.1999 Launched May 2002 First light Feb. 2000 First light June 2002 Science Applications – Land, oceans, and atmosphere – Nearly 40 science products generated and distributed Page 2
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) Wolfe - Nov 09 HDF Workshop 3
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 Wolfe - Nov 09 HDF Workshop 4
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 Wolfe - Nov 09 HDF Workshop 5
VIIRS Land Bands VIS NIR SWIR MWIR LWIR
VIIRS Visible, NIR and SWIR Bands • bbb – ccc CO2 O2 O3 O2 H2O H2O O2 H2O H2O H2O H2O CO2
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 Wolfe - Nov 09 HDF Workshop 8
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 Wolfe - Nov 09 HDF Workshop 9
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 (mid2011) – This will only be available to the general science community if NASA policy changes Wolfe - Nov 09 HDF Workshop 10
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) Wolfe - Nov 09 HDF Workshop 11
MODIS/Aqua Haze over China and Korea Oct. 28, 2009 Wolfe - Nov 09 HDF Workshop 12
... (and VIIRS Land) Current and Future use of HDF. 1. MODIS (and VIIRS Land) Current and Future use of HDF Robert Wolfe NASA Goddard Space Flight Center ...
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