Information Technology: GrADS

INTEGRATEDUSER INTERFACE

Maps, Charts, Animations

Expressions, Functions of Original Variables

General slices of {

4D GridsIn Situ ObsImages

User Definable,Extensible

Arbitrary DomainsOptimized for Typical Queries

Accessing, SubsettingAnalyzing

Visualizing

Interactive Quantitative

GrADS Analysis Model

ENABLES VERY SOPHISTICATED ANALYSIS TASKSIN A HIGHLY ENCAPSULATED WAY

Scientists only need to specify:• dimension constraint• list of data sets • GrADS expression

This unique, innovative approach to geophysical data analysis is the major reason for GrADS’ popularity.

Data Access/Interoperability/Analysis

• Level 0: FTP & basic Web capability.

• Level 1: DODS server concept: general data subsetting; metadata. Client can support data interoperability.

• Level 2: Analysis server. Uses GrADS unique encapsulated analysis capability.

Example: Calculate – at the server! – sea level pressure anomaly

over N. America when tropical Pacific SSTA > 1.0. Return the result – as data ! – to the desktop.

Size of data sets: 3GB (Level 0)Data processed at server: 5 MB (Level 1) Returned to client: 10KB (Level 2)

Examples of GrADS Used on the Web to Deliver Images

NCDC - http://www.ncdc.noaa.gov/onlineprod/prod.html

CDC - http://www.cdc.noaa.gov/USclimate/

CPC - http://www.cpc.ncep.noaa.gov/products/

DOLMS - http://dao.gsfc.nasa.gov/monitoring/

DOLMS Ozone - http://dao.gsfc.nasa.gov/monitoring/

DAO – TerraNCDCNCEP – CPCNOAA – CDC

Data Access/Interoperability/Analysis

• Level 0: FTP & basic Web capability.

• Level 1: DODS server concept: general data subsetting; metadata. Client can support data interoperability.

• Level 2: Analysis server. Uses GrADS unique encapsulated analysis capability.

Example: Calculate – at the server! – sea level pressure anomaly

over N. America when tropical Pacific SSTA > 1.0. Return the result – as data ! – to the desktop.

Size of data sets: 3GB (Level 0)Data processed at server: 5 MB (Level 1) Returned to client: 10KB (Level 2)

DODS

• Client/server architecture• http protocol• Generic, flexible data model• Metadata distribution capability• “Open your data set with a URL

instead of a filename”

Data Access/Interoperability/Analysis

• Level 0: FTP & basic Web capability.

• Level 1: DODS server concept: general data subsetting; metadata. Client can support data interoperability.

• Level 2: Analysis server. Uses GrADS unique encapsulated analysis capability.

Example: Calculate – at the server! – 500 hPa geopotential height

anomaly over N. America when tropical Pacific SSTA > 1.0. Return the result – as data ! – to the desktop.

Size of data sets: 3GB (Level 0)Data processed at server: 5 MB (Level 1) Returned to client: 10KB (Level 2)

GrADS-DODS Analysis Server

GRIB dataNetCDF data

GrADS data

etc..

datasets in any format supported by GrADS

Result cache

holds temporary data (uploaded, generated by a previous operation, or transferred directly from another server) for use in remote analysis

GrADS batch mode

interface code

DODS server libraries

Server

performs analysis

operations

manages sessions, translates dataset

names

Java servlet

supports extended request types for analysis, upload

internet

DODS data and requests

Joe Wielgosz: 5/25/00

DODS client libraries

GrADS

Matlab

IDL

etc..

data appears to client as local file, in a standard format (i.e, NetCDF, etc.)

Client

Encapsulated Analysis Requests

Summary: GrADS-DODS Server

• Share data: Enterprise-wide; Internet-wide --- data-format independent

• Data interoperability: Consistent metadata for many data types

• Distributed analysis: Reduces network load; improves interactivity

• Automation of analysis techniques: Analysis techniques can be captured in the form of scripts and provided on server and/or client

Desktop Weather Forecasting

NCEP

Global Weather Forecasts

NCEPNCEPGlobal Weather

ForecastsGlobal Weather

Forecasts

COLACOLAGrADS-DODS

ServerGrADS-DODS

Server

Region-SpecificLateral BCs

WWWWWW

PC-BasedRegional NWP