SO2 data and alert service

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Product information

Introduction
 
Slant column density vs.
vertical column density
Geographic regions
Data presentation
and delivery
Solar Zenith Angle
What is the Dobson Unit?
 
Slant column retrieval
Background correction
Reference spectrum
Cloud cover fraction
 
Near-real time service
Criteria for exceptional
SO2 concentrations
 
Air-mass factor using
look-up tables
Air-mass factor using a
chemistry transport model
SO2 column from OMI
 
Time period of
available data
Data format specification
Data and Service
version history
Validation of the
data products
South Atlantic Anomaly
 
Downloading
data & image files
Documentation
References
Acronyms
Acknowledgments

 
NOTE:   This is the OLD product info. Some parts of it are no longer up to date, while other parts are missing -- see the remark on the main product info page.

Specification of the data file formats

The data used to make the images (maps) available at the website are in general also available in some form. Both the availability and the form depend on the satellite instrument: See also the section on the Presentation and delivery of the data. Links to the relevant data files -- if available -- are given on the web pages showing the images (maps).

 

SCIAMACHY based data

The SO2 data based on SCIAMACHY is delivered in two forms:
  • as ASCII files for daily data at the coordinates of the measurements, in other words: at orbit coordinates

  • as HDF-4 files for dialy data, 3-day composites [SCIAMACHY and GOME-1 only] and monthly averages at the coordinates of a rectangular latitude-longitude grid
The data product files mention, among others, version number (see the chapter Process version history). They also have been given a product status, for a quick-look indication on the status of the data product:

 
status description
NRT data for SO2 column data delivered via the Near-real time Service (only for the ASCII data files)
preliminary data for data delivered via the Archive Service, either just the slant column, or including a preliminary vertical column
archive data for slant column and vertical column data delivered via the Archive Service

 
The data file structure is described on separate pages:

 
===> Some notes regarding downloading of data files and images

 

OMI based data

The SO2 data based on OMI measurements at orbit coordinates is provided by NASA in their HDF5-EOS format. The NRT data used for the images is not available for download to third parties. The off-line data usually follows 2 or 3 days later and is available via the NASA website via this page, which also gives access to a description of the (rather complex) data format.

It is not yet certain whether daily composites of OMI data on a latitude-longitude grid will be made. Monthly average data will be provided on the same grid as the SCIAMACHY data, in the same format: HDF-4; see the links above for more information.

 

 

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