NextGen Network-EnabledWeather (NNEW) Concepts

Aaron Braeckel

Representational Concepts

GIS Community (OGC)Feature“An abstraction of a real-world phenomenon”. !!!

Coverage“A feature that has multiple values for each attribute type”

Meteorological CommunityGridded DataRegular or *irregular multi-dimensional gridsNotable for several shared characteristics (efficiency, re-sampling, etc.)

Non-Gridded DataEverything else!

Service Mapping

WFS

WFS

WMS

WFS

•Point (PIREPs, METARs)•Area (AIR/SIGMETs)•Fronts•Others?

WCS WCS

WCS?

Thanks Oliver!

Integration

Gridded Data FormatsPrimary IOC products are regularly-spaced grids (including radar and other polar products!)

Standards-based options:•GML (XML)•GRIB 1•GRIB 2•HDF5 (with convention)•NetCDF 3 (with convention)•NetCDF 4 (with convention)•JPEG 2000?

Fastest growth in meteorological data volume is with gridded products

WCS and Gridded Data

Service ProviderService Provider

WCSRI

Gridded Data Store(Backing Store)

Request(HTTP, XML)

Data ConsumerSystem

Response

WCSRI Backing StoreThe WCSRI uses the NetCDF Java API for backing store access

Can acces many gridded file formats:•NetCDF 3 and 4 (with a convention)•HDF 4 and 5•GRIB 1 and 2•Gini•GeoTIFF•NEXRAD Level 2•NIDS/NEXRAD Level 3•McIDAS•…

To test whether a file is geo-locatable and an interpretable grid, use the most recent version of ToolsUI and open the file in the “Grids” section of the “Feature Types” tab

GML

Very flexible data modelTransparent (human-readable)

•Standard gridded data representations still being tuned•Extremely inefficient (CPU and compactness), even with binary/efficient XML techniques

Not supported as a backing store formatNot supported as a response format

GRIB 1 and 2

Undisputed leader in compactnessWMO Standard, in heavy use in operational MET

•Random access can be slow•Not always self-describing•Relatively restrictive model

GRIB 1 and 2 are supported as a backing store formatGRIB 2 will be supported as a response format*

HDF5

Heavily used within NASATypically used with a convention for geo-location and further standardizationGeneral-purpose formatA number of advanced features (parallel I/O, nodes, groups)

•Has some quirks•Used less frequently in meteorological communities

Supported as a backing store formatNot supported as a response format

NetCDF 3

General-purpose N-dimensional formatNASA and OGC standardHeavy use within research communitiesTypically used with a convention for geo-location and further standardization

•Limited compression (!)•Governed with less formality

Supported as a backing store formatNot supported as a response format

NetCDF 4

Nearly identical data model to NetCDF 3Based off of HDF5, with intentional restrictionsTypically used with a convention for geo-location and further standardization

•Governed with less formality

Supported as a backing store formatSupported as a response format

NetCDF Conventions

Large number in useTypically specify a “style” for specifying certain information

Climate and Forecast Convention (CF)Most popular NetCDF conventionExtends and generalizes several other conventions (COARDS, etc)

Covers:•Filenames•Standard field names•Missing data•Coordinate reference systems•Units (time, horizontal, vertical)

NetCDF Conventions

Several conventions in active useTypically formally managedSpecify a “style” for specifying certain information

Climate and Forecast Convention (CF)Most popular NetCDF conventionExtends and generalizes several other conventions (COARDS, etc)

Covers:•Filenames•Standard field names•Missing data•Coordinate reference systems•Units (time, horizontal, vertical)

CF Example

ResourcesNNEW – https://wiki.ucar.edu/display/NNEWD/NNEW+Dissemination+home+pageExperimental ADDS – http://weather.aeroOperational ADDS – http://adds.aviationweather.govOGC – http://opengeospatial.orgNNEW Phase 1 access - https://wiki.ucar.edu/display/NNEWD/NNEW+Phase+1+Access+Information