10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 1

Storing EOS data using HDF5 Archival Information

PackageMuQun Yang (The HDF Group)

Choonghwan Lee (The HDF Group)Ruth Duerr (NSIDC )

2

Definitions of some terms• CDM(Common Data Model)

• Unification of the data models of OpenDAP, netCDF and HDF5

• netCDF-4(network Common Data Form 4)• Library manipulating array-oriented

scientific data• CF-Conventions

• Convention of metadata providing spatial properties, among climate research community…

• CLASS (Comprehensive Large Array-data Stewardship System)• Electronic library of NOAA environmental

data10/16/2008

HDF and HDF-EOS Workshop XII, Aurora, CO

3

Prerequisite• METS(Metadata Encoding & Transmission

Standard)• Standard for encoding structural metadata

digital library • ISO-19115

• Schema for describing geographic information(former FGDC)

• 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)10/16/2008

HDF and HDF-EOS Workshop XII, Aurora, CO

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 4

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

10/16/2008HDF and HDF-EOS Workshop XII,

Aurora, CO 55

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

ECS Users

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/

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 6

$ ./h4toh5 –eos –nc4 input.he2 output.nc4

7

Challenges to do the conversion

• Retrieve geo-location information from HDF-EOS2 data

• Conform to NetCDF4 data model in the existing H4toH5 conversion tool

• ……

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO

• Grid lacks geolocation fields• Use predefined projections

• Geographic• Sinusoidal• Polar stereographic• …

• New converter creates geolocation fields• HDF-EOS2 API GDij2ll()

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 8

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

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 9

. . .. . .. . .. . .. . .. . .. . .. . .. . .

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

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 10

Challenges in conforming to NetCDF4

. . .. . .. . .. . .. . .. . .. . .. . .. . .

. .. .. .. .. .. .. .. .. .

. . .. . .. . .. . .. . .. . .. . .. . .. . .

Data field has three columnsLongitude field has two columnsNew longitude has three columns

1110/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO

Now some examples to show NetCDF4 files

converted from EOS2

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 12

A netCDF-4 file converted from EOS2 data at NSIDC

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 13

A netCDF-4 file converted from EOS2 data at NSIDC

Deliverables and future work• Deliverables

1. Enhanced HDF4 to HDF5 conversion toolhttp://hdfgroup.org/h4toh5/

2. A validation tool to verify the correctness of the conversionWill be released soon!

• Potential future work1. Reduce the output file size2. Improve the performance

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 14

10/16/2008HDF and HDF-EOS Workshop XII, Aurora,

CO 15

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.