An Update on GrADS and the GDS and their Application to a

Searchable Metadata Catalog

Jennifer Miletta AdamsIGES/COLA

10-Minute Outline

• Changes planned for GrADS version 2

• GrADS and GDS, a coupled system

• Greta, the GrADS Metadata Search Engine

Relevant New Features in GrADS version 2

• A true 5th dimension for ensemble members‘set X, Y, Z, T, or E’

• A virtual dimension for forecast time‘display temp(ft=2)’‘display temp(ftime=12z19Jun2006)’

Ensembles: Same Length, Same Initial Time

Time Axis ---->

Ens

embl

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Ensembles: Same Length, Different Initial Times

Time Axis ---->

Ens

embl

e M

embe

r

Ensembles: Same Length, Different Initial Times

Time Axis ---->

Ens

embl

e M

embe

r

Ensembles: Same Length, Different Initial Times

Time Axis ---->

Ens

embl

e M

embe

r

Ensembles: Different Lengths, Different Initial Times

Time Axis ---->

Ens

embl

e M

embe

r

GrADS Metadata Requirements for Characterization of Ensemble Members

• Ensembles must all share common time axis

• Unique name / number

• Initial time

• Length (in time axis units)

The GrADS-GDS Coupled System

• The GDS serves all data sets that GrADS can read• GrADS is a client for all GDS data sets• The NetCDFification of the ensemble metadata

must be meaningful to GrADS • No known metadata standard for ensembles

A Searchable GrADS Metadata Catalog: “Greta”

Multiple disk servers fill up with scientific data. A nightly crawl finds all GrADS-readable data sets and configures a local GrADS Data Server (GDS).

Greta crawls each GDS in the suite of disk servers. All metadata for every data set on disk is indexed. The searchable catalog is updated nightly.

Users at their desktops search with a browser or the unix interface to find data of interest and then interactively look at it with GrADS.

1-Minute Wrap-Up• Changes planned for GrADS version 2 -- 5th dimension for ensemble members -- Virtual dimension for forecast time

• GrADS and GDS, a coupled system -- Wherever GrADS goes, GDS will follow

• Greta, the GrADS Metadata Search Engine -- A searchable metadata catalog for all of COLA’s data holdings

Overtime

Please talk to me during breaks about:• GRIB2 and compressed HDF data formats• OPeNDAP servers and clients for in situ data