Accessing the Data

DAP (Data Access Protocol)

OPeNDAP, an acronym for "Open-source Project for a Network Data Access Protocol", is a data transport architecture and protocol widely used by earth scientists. The protocol is based on HTTP and the current specification is OPeNDAP 2.0 draft. OPeNDAP includes standards for encapsulating structured data, annotating the data with attributes and adding semantics that describe the data. The protocol is maintained by OPeNDAP.org, a publicly funded non-profit organization that also provides free reference implementations of OPeNDAP servers and clients.

DAP Clients

Download NetCDF-C

To view the metadata for a dataset from a command line terminal with netcdf-4 C installed on the host:

$ ncdump -h http://tds.glos.us/thredds/dodsC/SST/LakeOntarioSST-Agg
        netcdf LakeOntarioSST-Agg {
        dimensions:
          lat = 842 ;
          lon = 1906 ;
          maxStrlen64 = 64 ;
          time = 171 ;
        variables:
          char crs(maxStrlen64) ;
            crs:grid_mapping_name = "latitude_longitude" ;
            crs:longitude_of_prime_meridian = 0. ; 
          ...

To download the dataset to your local machine from the command-line:

nccopy -k 3 http://tds.glos.us/thredds/dodsC/SST/LakeOntarioSST-Agg LakeOntarioSST-Agg.nc

Download NCTOOLBOX

nctoolbox is a Matlab toolbox that provides read-only access to common data model datasets. Under the hood, nctoolbox uses NetCDF-Java as the data access layer. This allows nctoolbox to access NetCDF, OPeNDAP, HDF5, GRIB, GRIB2, HDF4 and many (15+) other file formats and services using the same API. It works with Matlab 2008a and later.

Demos that display basic functionality are available on github: here

download netcdf-java

the netcdf java library implements the common data model (cdm) to interface netcdf files and other types of scientific data formats.

unidata’s common data model (cdm) is an abstract data model for scientific datasets. it merges the netcdf, opendap, and hdf5 data models to create a common api for many types of scientific data. the netcdf java library is an implementation of the cdm which can read many file formats besides netcdf. we call these cdm files, a shorthand for files that can be read by the netcdf java library and accessed through the cdm data model.

Download netCDF4 for Python

Opening Datasets in Python

The netCDF4 module does most of the work for us. In order to open up the dataset:

from netCDF4 import Dataset
nc = Dataset('http://tds.glos.us/thredds/dodsC/SST/LakeOntarioSST-Agg')

nc.variables
--> OrderedDict([(u'crs', ), (u'lat', ), (u'lon', ), (u'time', ), (u'sst', )])

Download Panoply


Opening Datasets in Panoply

Panoply Add Remote Dataset

Panoply Add URL

Create Dataset


WMS (Web Map Service)

A Web Map Service (WMS) is a standard protocol for serving georeferenced map images over the Internet that are generated by a map server using data from a GIS database. The specification was developed and first published by the Open Geospatial Consortium in 1999.

WMS Clients

Download ArcGIS Explorer

Explorer for ArcGIS lets you interact with your organization's maps and data no matter where you are. Whether you are a seasoned GIS professional or have no prior GIS knowledge, you can become immediately productive with the app to make more informed decisions.

Download Google Earth

Google Earth lets you fly anywhere on Earth to view satellite imagery, maps, terrain, 3D buildings, from galaxies in outer space to the canyons of the ocean.

See how to add WMS layers to Google Earth

Download NASA World Wind

World Wind is an open-source (released under the NOSA license) virtual globe first developed by NASA in 2003 for use on personal computers and then further developed in concert with the open source community since 2004. The original version relied on .NET Framework, which ran only on Microsoft Windows. The more recent Java version, World Wind Java, is cross platform, a software development kit (SDK) aimed at developers and, unlike the old .NET version, not a standalone virtual globe application in the style of Google Earth. The SDK includes a suite of basic demos, available at goworldwind.org. The World Wind Java version was awarded NASA Software of the Year in November 2009. The program overlays NASA and USGS satellite imagery, aerial photography, topographic maps, Keyhole Markup Language (KML) and Collada files.

Adding WMS to Nasa World Wind

NASA World Wind

Download uDig

uDig is a GIS software program produced by a community led by Canadian-based consulting company Refractions Research. It is based on the Eclipse platform and features full layered Open Source GIS. It is written in Java and released under EPL and BSD licences (formerly under GNU LGPL).

Adding WMS Layers in uDig

uDig Menu

uDig WMS

uDig URL

uDig Selection

See Godiva in action

Godiva 2 is a WMS client that is integrated directly into the THREDDS Data Server. It comes as part of a standard THREDDS installation and provides clients with the ability to see WMS datasets hosted on a THREDDS instance in a proper WMS interface. The nice thing about Godiva is that it requires no configuration other than enabling a WMS dataset on the THREDDS instance, and it has a decent featureset for being a micro-client.


SOS (Sensor Observation Service)

The Sensor Observation Service (SOS) is a web service to query real-time sensor data and sensor data time series and is part of the Sensor Web. The offered sensor data comprises descriptions of sensors themselves, which are encoded in the Sensor Model Language (SensorML), and the measured values in the Observations and Measurements (O & M) encoding format. The web service as well as both file formats are open standards and specifications of the same name defined by the Open Geospatial Consortium (OGC).

SOS Clients

Pyoos

A Python library for collecting Met/Ocean observations

Pyoos attempts to fill the need for a high level data collection library for met/ocean data publically available through many different websites and webservices.

Download Environmental Data Connector

RPS ASA

EDC

The Environmental Data Connector (EDC) is a tool that allows users to connect to THREDDS/OPeNDAP/SOS/ERDDAP servers and download environmental data. It was developed for the National Oceanic and Atmospheric Administration (NOAA) Fisheries by Applied Science Associates, Inc. (ASA). Version 1.3 of the EDC is available in five versions: EDC for ArcGIS 10.X, EDC for Matlab, EDC for R, EDC for Excel and EDC Standalone.

download sensor web client

the "sensor web client" (formaly known as thinsweclient) is a web-based client application which offers an easy to use interface to generate graphs from near-realtime sensor data. the client hides technical details of swe services and protocols, so that even non-experts can use components of the sensor web transparantly. to enable maximal platform independence the client is developed as a web-based browser application, making use of newest web technologies such as asynchronous client/server communication.


WCS (Web Coverage Service)

A WCS provides access to coverage data in forms that are useful for client-side rendering, as input into scientific models, and for other clients. The WCS may be compared to the OGC Web Feature Service (WFS) [4] and the Web Map Service (WMS) [5]. As WMS and WFS service instances, a WCS allows clients to choose portions of a server's information holdings based on spatial constraints and other query criteria.

Unlike OGC Web Map Service (WMS), which portrays spatial data to return static maps (rendered as pictures by the server), the Web Coverage Service provides available data together with their detailed descriptions; defines a rich syntax for requests against these data; and returns data with its original semantics (instead of pictures) which may be interpreted, extrapolated, etc., and not just portrayed.

WCS Clients

Download ArcGIS

Esri's ArcGIS is a geographic information system (GIS) for working with maps and geographic information. It is used for: creating and using maps; compiling geographic data; analyzing mapped information; sharing and discovering geographic information; using maps and geographic information in a range of applications; and managing geographic information in a database.

Download gvSIG

gvSIG is a geographic information system (GIS), that is, a desktop application designed for capturing, storing, handling, analyzing and deploying any kind of referenced geographic information in order to solve complex management and planning problems. gvSIG is known for having a user-friendly interface, being able to access the most common formats, both vector and raster ones. It features a wide range of tools for working with geographic-like information (query tools, layout creation, geoprocessing, networks, etc.), which turns gvSIG into the ideal tool for users working in the land realm.