1. H. Michael Goodman Earth-Sun System Division NASA Headquarters
Proposed Precipitation Metadata and Content Standards International Precipitation Working Group 27 October 2004
H. Michael Goodman
Earth-Sun System Division
NASA Headquarters

2. Outline of Presentation
Basis for Standards
Background Information
Strawman Precipitation Standards
Charge to the Working Groups

3. 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)

4. 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

5. Background for Precipitation Standards
NASA’s 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

6. 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

7. Strawman Level-2 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

8. 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

9. 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?

10. Backup
Backup

11. The Standards Process
Modeled on Internet Engineering Task Force “RFC” process and tailored to meet NASA’s 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

12. Components of a Future Global System for Earth Observation

13. Current Earth Science Research Assets in Space
We have given the world its first capability to study the Earth as a system
Jason
Landsat 7
SORCE
Aqua
SAGE III
QuikScat
EO-1
SeaWiFS
ICESat
TRMM
SeaWinds
ACRIMSAT
TOMS-EP
ERBS
Terra
GRACE
TOPEX/Poseidon
UARS