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GlobWave Satellite Data

GlobWave will allow easy access to a harmonised set of Altimeter and SAR products.

Here we outline what the GlobWave data is and how it can be accessed.

For full details of all GlobWave data products and their content, please access the GlobWave Product User Guide.

What is the GlobWave satellite data?

The GlobWave satellite products give a “uniform” set of along track satellite wave data from all available Altimeters (spanning multiple space agencies) and from ESA Synthetic Aperture Radar (SAR) data.

The main parameters to be measured are:-

  • Altimeter: Significant Wave Height and Backscatter Coefficient (Sigma0)
  • SAR: Swell Significant Wave Height, dominant wavelength (per spectral partition) and mean direction (per spectral partition)

How is it different from the original native products provided by the Space Agencies?

One question that often gets asked is “how is a GlobWave satellite data stream different to the native data stream” e.g. the Envisat Altimeter delayed mode product vs the GlobWave delayed mode product?

The answer is that the corresponding GlobWave product file will contain the wave related parameters from the native product plus a series of important additional information. These include a consistent quality flag and error characterisation definition across all GlobWave data streams as well as ancillary data from ECMWF numerical models such as distance to coast, bathymetry and sea surface temperature. A full description of the additional information is provided by the blue text in section 4.3 of the Product User Guide.

Also, all GlobWave data streams come in the same format, which is netCDF-3 with CF (v1.4) conventions. This ensures that minimal time is spent writing ingestion routines and maximum time is spent doing interest science and applications with the data.

Exactly what data streams are supported?

We allow free access to both SAR and Altimeter data sets in both real time and delayed mode. The delayed mode data consists of 12 data streams from 9 satellites and stretches back as far as 1985 with GEOSAT. Further details are outlined in the following table:

Source

Type

Dates

ESA ERS-1

Altimeter

01/02/1992 – 02/06/1996

ESA ERS-2

Altimeter

15/05/1995 – 22/06/2003[1]

ESA ERS-1

SAR

01/01/1991– 01/12/1996

ESA ERS-2

SAR

01/01/1996 - 04/7/2011

ESA Envisat

Altimeter

26/08/2002 - 08/04/2012

ESA Envisat

SAR

17/12/2002 - 08/04/2012

CNES/NASA Topex/POSEIDON

Altimeter

25/09/1992- 08/10/2005

CNES/NASA Jason-1

Altimeter

15/01/2002 onwards

CNES/NASA Jason-2

Altimeter

01/12/2008 onwards

US Navy GEOSAT

Altimeter

31/03/1985-30/12/1989

US Navy/NOAA GEOSAT Follow On

Altimeter

08/01/2000 - 23/07/2008

ESA / NOAA CryoSAT-2

Altimeter

28/01/2011 onwards

The near-real-time data consists of 4 data streams from 3 satellites and is available from GlobWave within about 3 hours of the actual observation from space. Further details are outlined in the following table:

Source

Type

Dates

ESA Envisat

Altimeter

26/08/2002 - 08/04/2012

ESA Envisat

SAR

17/12/2002 - 08/04/2012

CNES/NASA Jason-1

Altimeter

15/01/2002 onwards

CNES/NASA Jason-2

Altimeter

01/12/2008 onwards

How I do I get access to the data?

The data is hosted on an ftp site. Username and password details can be obtained by e-mailing the CERSAT Help Desk at fpaf@ifremer.fr with the subject: GlobWave Data Access. We recommend that you consult sections 3 and 4.4.6 of the Product User Guide regarding essential information and known issues respectively.

If you already have a username and password then you can browse the data on the ftp site by clicking here.

READ MORE

Accessing GlobWave data

GlobWave data can be accessed in various ways in order to ease the user's life, depending on wether you want to retrieve a complete archive or just subsets of data.

Standard ftp access

All the data are hosted on an ftp site. Username and password details can be obtained by e-mailing the CERSAT Help Desk at fpaf@ifremer.fr with the subject: GlobWave Data Access. We recommend that you consult sections 3 and 4.4.6 of the Product User Guide regarding essential information and known issues respectively.Remember that satellite real-time data are usually available online within 3 hours after end of onboard acquisition, whereas the geophysical quality records (GDR products) are updated on the site every 6 months.

If you already have a username and password then you can browse the data on the ftp site by clicking here.

On-demand requests

If you can't retrieve the complete archive through ftp or any available online means, it is possible to ship the data to you. You will have first to ship us an external hard-drive with sufficient amount of free disk space, we will then copy the data on it and ship back to you your hard-drive at no cost. In order to set up such arrangement, please first contact the CERSAT Help Desk at fpaf@ifremer.fr.

The hard drive will have to be shipped to :

Jean-François Piollé
IFREMER - CERSAT
Site de la Pointe du Diable
29280 Plouzané
France

Naiad dataminer

Naiad is a third-party tool, developed by Ifremer, to select, subset, remap and extract satellite swath and gridded data through a user-friendly interface or webservices. It provides access to all GlobWave satellite GDR products (L2P). Check here for more information.

Scripting

The web services provided by Naiad allow users to build there own scripts to select, query, transform or extract the GlobWave data. As an example we provide here an example in python language of a script retrieving the list (and urls) of the data files matching a user selected area and time frame. This can be easily translated in any other language if you are not familiar with python and can be used for instance to automate queries for NRT data once there will ingested into Naiad system (before Summer 2011).

Scripting access to GlobWave L2P data

The following script is intended to retrieve the list and urls of the data files of a given GlobWave product matching a user defined area and time period of interest.

Read more...
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Demo Products

The GlobWave portal will provide a facility to archive and distribute demonstration wave products.

Such demonstration wave products should be at least partly derived from satellite data, based on new techniques of new types of satellite data. An initial set of demonstration products has been made available by the GlobWave Consortium which are outlined in the subsections below.

We plan to grow the set of demonstration products available via the GlobWave Web Portal during the lifetime of the project and this will depend on members of the wave community working with us so that we can host some of their exciting research concepts!

As innovators within your field, we are looking to the wave user community to offer existing products that could be integrated as part of the GlobWave initiative. This offers a fantastic outreach opportunity for your organisation and helps us to stimulate involvement from the wave community at large, a key objective of GlobWave.

Please find an application form here with which to inform us about your exciting demonstration products. Please contact geoff.busswell@logica.com or clive.farquhar@logica.com with any questions.

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The following links may also prove useful for access to existing SAR and Altimeter wave products:

Data Product Levels are the classification of data products by the sort of processing used in their generation and, to a lesser extent, the sort of uses to which these products might be put.

While the project will strive to ingest more in situ data sources a number of in situ data sources will be used as a starting point based on the geographic location, size of network and the provision of quality checked data.

This section area has been constructed to allow users to easily reach all the GlobWave data/services of interest.