Proposed Precipitation Metadata and Content Standards International Precipitation Working Group 27 O

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Proposed Precipitation Metadata and Content
StandardsInternational Precipitation Working
Group 27 October 2004

• H. Michael Goodman
• Earth-Sun System Division
• NASA Headquarters

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Outline of Presentation

• Basis for Standards
• Background Information
• Strawman Precipitation Standards
• Charge to the Working Groups

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Basis

• Data systems face obstacles in their contribution
  to science and applications
• Heterogeneous sensors, platforms, projects, and
  campaigns
• Changing content, multiple formats, disparate
  projections, etc.
• Multiple means of searching, discovery, packaging
  and delivery of data
• Standards enable data systems interoperability
• Standards can contribute to science success and
  interoperability within their discipline
• Downstream users have known, well documented
  path to use the data
• Operational benefit for a common set of protocols
  for discovery and interchange
• Engineering benefit to limiting the range of
  encoding (i.e., the number of different formats)

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Insights

• Interoperability does not require homogeneous
  systems, but rather coordination at the
  interfaces
• Discipline communities have wherewithal and the
  solutions
• NASA is seeking community leadership

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Background for Precipitation Standards

• NASAs Earth Science Data Systems Standards
  Process Group explored the possibility of
  identifying disciplines where metadata or content
  standards could have an impact
• Small focus group of precipitation scientists
  were identified
• George Huffman, Phil Arkin, John Bates, John
  Janowiak, Chris Kummerow, Jeff McCollum, and Joe
  Turk
• Initial discussion focused on
• Discussed feasibility of creating a content
  standard for precipitation data files
• Level-2 precipitation standards considered as a
  reasonable goal
• Standards must be extensible to allow for new
  parameters as innovations in algorithms improve
  the science
• Agreed that small number of mandatory metadata
  and data content parameters would be useful
• Suggested additional optional metadata and data
  parameters to improve the usability

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Strawman Level-2 Metadata Standards

• Metadata Content
• Orbit Segment Standard
• Start date and time (yyyymmdd and hhmmssss)
• End date and time
• Number of scans in the orbit segment
• Platform (satellite) identifier
• Sensor name
• Processing algorithm and version
• Processing date
• Point of contact information
• Pointer to documentation
• Optional Parameters permit but not require
• Orbit number of low-Earth orbit data (highly
  recommended)
• Number of leading scans duplicated from previous
  orbit segment
• Number of trailing scans duplicated from
  following orbit segment
• Calibration source data set and version number

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Strawman Level-2 Data Content

• Data Content
• Each Field of View Standard
• Latitude and longitude
• Date and time
• Surface precipitation estimate (mm/hr)
• specify instantaneous or time averaged
• Precipitation quality estimate
• e.g., RMS, bias, ambiguous flag
• Sensor quality flag
• Geolocation quality flag
• Scan position index (or fractional orbit number)
• Cell (location) number within scan

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Optional Level-2 Data Content

• Optional Parameters
• Precipitation type i.e., convective or
  stratiform
• Spacecraft position, velocity, and altitude at
  the start of the scan
• Surface flag (e.g., land, coast, or ocean)
• Fractional land coverage
• Additional precipitation variables (e.g.,
  near-surface, vertical structure
• Precipitation quality estimates for any
  additional precipitation variables
• Additional geophysical variables
• e.g., total precipitable water, total
  precipitable ice, latent heat structure

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Charge to Each Breakout

• Would like each breakout group to discuss the
  strawman metadata and data content standards.
  Consider
• Is there consensus for a need Level-2
  precipitation standards?
• Which parameters should be considered standard
  vs. optional?
• Is there agreement for date and time, satellite
  and sensor identifiers?
• Need to establish consistent algorithm versions
  across different satellites/sensors.
• Should data gaps be filled in with missing data
  values?
• Should there be provisions for identifying the
  number of leading and trailing scans in an orbit
  segment?
• How do we handle the difference in the parameters
  needed to describe low-Earth vs. geostationary
  observations (e.g., orbit )
• Should there be a similar agreement on the
  content of basic documentation provide by each
  dataset developer?

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Backup

• Backup

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The Standards Process

• Modeled on Internet Engineering Task Force RFC
  process and tailored to meet NASAs
  circumstances. The standards process provides
• Credibility - "peer" and "stakeholder" review of
  proposed standards will establish trust that
  standards are sound.
• Transparency - within NASA and allied
  communities, the progress of standards decisions
  will be evident
• Workability - implementation examples and
  evidence of operational success will encourage
  adoption of standards that are known to work
• Timeliness - standards adoption will keep up with
  technological innovation
• Relevance - standards will be responsive to
  science and data systems requirements
• Potential wider use of standard outside of
  proposing community

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Components of a Future Global System for Earth
Observation
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Current Earth Science Research Assets in Space
We have given the world its first capability to
study the Earth as a system
Jason
EO-1
SeaWiFS
ICESat
ACRIMSAT
TOMS-EP
ERBS
TOPEX/Poseidon