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EOS Terra MODIS Quality Assurance Overview

EOS Terra MODIS Quality Assurance Overview. Joseph M Glassy, Director, MODIS Software Development at NTSG School of Forestry, Numerical Terradynamics Simulation Group University of Montana, Missoula Montana USA. Introduction. Goals:

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EOS Terra MODIS Quality Assurance Overview

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  1. EOS TerraMODIS Quality Assurance Overview Joseph M Glassy, Director, MODIS Software Development at NTSG School of Forestry, Numerical Terradynamics Simulation Group University of Montana, Missoula Montana USA

  2. Introduction • Goals: • Summarize our SCF Quality Assurance program (goals, protocols, interface to ECS) • Describe how QA/Validation information is organized, formatted, and retrieved. • Introduce key Quality Assurance concepts and techniques. • Invite feedback on how we can improve.

  3. Quality Assurance, Validation,and Evaluation • Distributed quality control measures integrated into a NASA operational mission is a relatively new approach (e.g. where SCF’s actively participate in QA beyond initial assignment). • Quality Control measures divided into QA, evaluation, and a formal validation program.

  4. Quality Assurance, Evaluation, and Validation • Quality Assurance: near-real-time, tile and pixel level evaluation of tile products. • Evaluation: reasonableness checks on trends towards “correctness” stopping short of saying outputs are “absolutely right” • Validation: after-the-fact analysis (formal, global) using sparse point comparisons (FluxNet, Core Validation sites, campaigns like Safari 2000, etc) to “try” to assess absolute accuracy…

  5. Quality Assurance • Two emphases: routine and trouble-ticket driven • Two scopes: tile level (ECS metadata) vs. pixel level (separate pixel QA, often as categorical scores) • Tile level QA: mandated EOSDIS Core System fields as searchable metadata, to qualify data orders, use of tiles in specific analysis applications • ECS Metadata :Object-Data-Lang./Parameter Value Lang (ODL-PVL) hierarchies.

  6. Quality Assurance Data Flow • Production at GSFC and/or MODAPS • Goal: SCF acquire(s) and analyze 5% of tiles • SCF check tile, pixel QA, then updates SCIENCEQUALITYFLAG and explanation… • SCF posts QA evaluation back to LDOPE • LDOPE updates DB at Eros Data Center • User orders, receives tile(s) with updated QA field(s).

  7. QA VALIDSfor SCIENCEQUALITYFLAG • Passed • Suspect • Failed • Inferred Passed • Inferred Failed • Being investigated • Not being investigated (default)

  8. ECS Tile Level Metadata • Appears in HDFEOS tiles as (3) file level character attributes: • StructMetadata.0 – tile geolocation parameters • CoreMetadata.0 – user searchable key fields to qualify Query/Orders and assessing usability in scientific analysis and field applications. • ArchiveMetadata.0 – overlapping info, more for ECS/EDC use in organizing archives. (ignore)

  9. CoreMetadata.0 Example • ODL/PVL information is organized into a nested hierarchy of object “stanzas” • QAPERCENTGOODQUALITY or, • QAPERCENTCLOUDCOVER may be helpful… • Example of a ODL/PVL stanza for LOCALGRANULEID • :CoreMetadata.0 = "\n", • "GROUP = INVENTORYMETADATA\n", • " GROUPTYPE = MASTERGROUP\n", • "\n", • " GROUP = ECSDATAGRANULE\n", • "\n", • " OBJECT = LOCALGRANULEID\n", • " NUM_VAL = 1\n", • " VALUE = \"MOD15A1.A2000208.h18v04.002.2000322020100.hdf\"\n", • " END_OBJECT = LOCALGRANULEID\n", • "\n", • " OBJECT = PRODUCTIONDATETIME\n", • " NUM_VAL = 1\n", • " VALUE = \"2000-11-17T02:01:01.000Z\"\n", • " END_OBJECT = PRODUCTIONDATETIME\n", • "\n",

  10. Embedded QA Bitfield Legend (via Noesys 2.0)

  11. ..all QA bitfields merged…

  12. MODLAND_QC ALGOR_PATH ...vs. each QA bitfield separated… CLOUD STATE (0=clear, 1=cloudy, 2=mixed, 3=not set) QC N. Pixels Rel. Frequency 0 648401 45.028 1 404148 28.066 2 82511 5.730 3 304940 21.176 CLOUD_STATE

  13. Quality Assurance Techniques • Tile level analysis using visualization tools like HDFLook, ENVI/IDL, Noesys, HDF-Explorer • Tile level statistical analysis & characterization • Multiple tile statistical characterizations, over time periods • Reprojection/mosaic post-processing, to import into GIS/RS environments, for formal comparison with other geo-spatial datasets.

  14. Quality AssuranceTools Available • Public domain: HDFLook (Lille,FR); Webwinds (JPL) • Commercial: Noesys, ENVI/IDL, HDF-Explorer • Future: ERDAS Imagine, PCI EasiPACE, ArcInfo • Open source utilities: reprojtool.exe, qcbits.exe, others as developed… • Ask your vendor to support HDF-EOS!

  15. Quality AssuranceResources Available • Consult MODIS Product User’s Guide and/or the product Abstract, available with orders at EDC • Consult main NASA EOSDIS Core System metadata web site: • observer.gsfc.nasa.gov/applied_tech/metadata • Main MODIS Quality Assurance URL is: • http://modland.nascom.nasa.gov/QA_WWW/qahome.html

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