using hdf5 archive information package to preserve hdf-eos2 data
DESCRIPTION
This one-year research project, funded by NOAA Climate Program Office (CPO) Scientific Data Stewardship (SDS), provides a solution to migrate data to a single standards-based archive format. Specifically, we investigate on how to store NASA ECS data and metadata into HDF5 Archival Information Packages (AIP). To achieve this, the HDF4 to HDF5 conversion tool has been enhanced so that converted ECS data can be read through the NetCDF4/CDM interface. In addition, metadata tools will be developed that convert ECS collection and granule level metadata to NOAA's collection level and NARA's METS standard. The enhanced HDF4 to HDF5 conversion tool has been released in May 2008 and it includes new functionality as the converted ECS data can be read through the NetCDF4 interface. We have tested 33 typical HDF-EOS2 swath, grid and point products at the National Snow and Ice Data Center (NSIDC). We also demonstrate the initial effort of the work to develop METS compliant metadata from granule metadata held in NASA's Earth Observing System (EOS) Data and Information System (EOSDIS) Core System (ECS).TRANSCRIPT
10/16/2008 HDF and HDF-EOS Workshop XII 1
Storing EOS data using HDF5 Archival Information Package
MuQun Yang (The HDF Group)
Choonghwan Lee (The HDF Group)
Ruth Duerr (NSIDC )
Definitions of some terms
• CDM(Common Data Model)• Unification of the data models of OPeNDAP,
netCDF and HDF5
• CF-Conventions• Convention of metadata providing spatial
properties, among climate research community…
• CLASS (Comprehensive Large Array-data Stewardship System)• Electronic library of NOAA environmental data
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Prerequisite
• METS(Metadata Encoding & Transmission Standard)• Standard for encoding structural metadata
• ISO-19115• International Schema for describing geographic
information
• File-level Metadata• Metadata about the individual file or granule
• Dataset-level Metadata• Metadata that applies to each and every
granule/file in the whole data set(product)
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HDF5 Archive Information Package
Data file HDF5
METS
Primary Schema Extension Schema
|<mets>|---<dmdSec>----------------<MODS>|---<amdSec>--------------|--<techMD>| |--<rightsMD>| |--<sourceMD>|----<fileGrp>|----<structMap>
http://www.hdfgroup.uiuc.edu/papers/papers/AIP/HDF5_AIP_White_Paper.pdf
HDF5 AIP Components
Metadata file
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NOAA SDS Program
NetCDF4/HDF5-data
NetCDF4 / HDF5 Data
METS
NSIDC/ ECS
HDF4-data
NCDC:CLASS
ISO-19115
HDF5-AIP
H4toH5
ECS to ISO-19115
NSIDC/ECS
Metadata
CDM/NetCDF4
ECS to METS
Enhanced H4toH5 conversion tool
• Convert HDF-EOS2 data to NetCDF4-compliant HDF5 data
• Official release (2.0) can be found at http://hdfgroup.org/h4toh5/
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$ ./h4toh5 –eos –nc4 input.he2 output.nc4$ ./h4toh5 –eos –nc4 input.he2 output.nc4
Challenges to do the conversion
• Retrieve geo-location information from HDF-EOS2 data
• Conform to NetCDF4 data model in the existing H4toH5 conversion tool
• ……
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• Grid lacks geolocation fields• Use predefined projections
• Geographic• Sinusoidal• Polar stereographic• …
• New converter creates geolocation fields• HDF-EOS2 API GDij2ll()
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Challenges: Handle EOS - Grid
Data [4][12]Lon[12]Data [4][8]Lon[4][8]
Geographic
Sinusoidal
• The size of geolocation fields can be different from data fields
• New converter has to handle geolocation fields correctly
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Challenges: Handle EOS - Swath
• Follow CF conventions• Create two variables: NewLongitude and
NewLatitude• Add to the data field an attribute coordinates=“NewLongitude NewLatitude”
• Keep the original Latitude and Longitude
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Challenges in conforming to NetCDF4
Data field has three columnsLongitude field has two columnsNew longitude has three columns
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Now some examples to show NetCDF4 files converted from EOS2
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A netCDF-4 file converted from EOS2 data at NSIDC
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A netCDF-4 file converted from EOS2 data at NSIDC
Deliverables and future work
• Deliverables1. Enhanced HDF4 to HDF5 conversion tool
http://hdfgroup.org/h4toh5/2. A validation tool to verify the correctness of the
conversion
Will be released soon!
• Potential future work
1. Reduce the output file size
2. Improve the performance
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Acknowledgement
This work was supported under NOAA Scientific Stewardship Program grant number NA07OAR4310286. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of NOAA.