Global Atmosphere Watch (GAW): monitoring of the ozone layer world map
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Ozone hole

GAW Research on Stratospheric Ozone

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What is ozone? How the ozone layer protects against harmful ultraviolet radiation from the sun

Ozone is a special form of oxygen with the chemical formula
O3. The oxygen we breathe and that is so vital to life on earth is O2.

Ozone constitutes a very small part of our atmosphere, but its presence is nevertheless vital to human well-being. Most ozone resides high up in the atmosphere, between 10 and 40km above Earth's surface. This region is called the stratosphere and it contains about 90% of all the ozone in the atmosphere.

Why do we care about atmospheric ozone?

Ozone in the stratosphere absorbs some of the Sun’s biologically harmful ultraviolet radiation. Because of this beneficial role, stratospheric ozone is considered “good” ozone. In contrast, excess ozone at Earth’s surface that is formed from pollutants is considered “bad” ozone because it can be harmful to humans, plants, and animals. The ozone that occurs naturally near the surface and in the lower atmosphere is also beneficial because ozone helps remove pollutants from the atmosphere.

Video about atmospheric ozone:

English version: "The ozone hole" , Q&A with Geir Braathen, WMO Senior Scientific Officer, Atmospheric Environment Research Division, Research Department.
French Version: "Le trou dans la couche d'ozone" Questions et réponses avec Geir Braathen, Fonctionnaire Scientifique Principal, Bureau de la Recherche Atmosphérique et de l’Environnement, Département de la Recherche, OMM.

WMO informs about the ozone layer

WMO informs about the state of the ozone layer in several ways:

Near-real time plots from Antarctic stations

Click here to access the page with NRT plots.



WMO Antarctic Ozone Bulletins

The third Bulletin for 2013 was published on 14 October. Click on the link below.


2012 2011
2010 Bulletin-1-2009
bulletin no. 1, 2008 cover_o3_bull07
Antarctic ozone bulletins 2005


An Overview of the 2005 Antarctic Ozone Hole,
by Geir O. Braathen (Warning: 26 MByte)

Ozone web page of the Servicio Meteorológico Nacional of Argentina

WMO Antarctic Ozone Bulletins from earlier years

Background information and summaries (1995-2003) by Andreas Fischer


WMO Arctic Ozone Bulletins

The Secretariat of the World Meteorological Organization, in collaboration with the European Ozone Research Coordinating Unit, issues annual bulletins containing information on the development of the Arctic ozone layer over the course of each winter.  The bulletins are based on data provided by WMO Members that operate atmospheric monitoring stations in the Arctic and satellites to observe ozone and related parameters globally.

Arctic ozone bulletin 2005-06

The 2006 issue is the first joint WMO/EC Arctic Ozone Bulletin.

Posters at conferences

Poster on the Antarctic ozone hole from 2003 to 2012.

Presentations at meetings, workshops and conferences

Presentation on the GAW Ozone Observing System given at the 14th Biennial Brewer User Group Meeting, Tenerife, 25 March 2014.

The 8th Ozone Research Managers' Meeting: Geneva 2-4 May 2011

The World Meteorological Organization, in collaboration with the United Nations Environment Programme (UNEP) is arranging the 8th Meeting of the Ozone Research Managers of the Parties to the Vienna Convention for the Protection of the Ozone Layer. Practical information can be found here.

The 7th Ozone Research Managers' Meeting: Geneva 18-21 May 2008

Information on the 7th ORM can be found here.


WMO/UNEP Scientific Assessment of Ozone Depletion

cover page main report 2002 assessment


More information about the WMO/UNEP Scientific Assessments of Ozone Depletion can be found at the ozone assessment web pages of NOAA.


Description of the GAW Ozone Observing System

The GAW total ozone and profile ozone networks were designated at baseline networks of the Global Climate Observing System (GCOS) in 2007. The documentation to describe the ozone observing system can be found here.

WMO brochure on the protection of the ozone layer




WMO coordinates the global ozone observing network

ozone observations

The WMO-GAW ozone observing system comprises more than 100 stations worldwide that measure total column ozone and ozone profiles in the troposphere and stratosphere. The WMO secretariat coordinates training and calibration excercises. The WMO-GAW World Calibration Centre for Dobson total ozone measurements is located at the Global Monitoring Division of NOAA. The WMO-GAW World Calibration Centre for Brewer total ozone measurements is located at Environment Canada.The WMO-GAW World Calibration Centre for ozonesonde measurements is located at Forschungszentrum Jülich, Germany.

The WMO-GAW ozone observing system provides important data for the assessment of the state of the ozone layer and the data are used in the quadrennial WMO/UNEP Scientific Assessment of Ozone Depletion (see above). Data from Antarctica are delivered in near-real time and used in the WMO Antarctic Ozone Bulletins (see above).

Data from the WMO-GAW ozone observing system are collected and stored at the WMO World Ozone and Ultraviolet Radiation Data Centre (WOUDC) at Environment Canada, Toronto.

Contributing Networks

Several observational networks are contributing to the overall GAW system. In the field of ozone observations these two networks are linked to GAW. Click on them to go to their respective web sites.

Network for the Detection of Atmospheric Composition Change (NDACC)

NDACC logo

Southern Hemisphere Additional Ozone Sonde Network (SHADOZ)



Useful links to stratospheric ozone and UV radiation web sites

WMO World Ozone and UV radiation Data Centre (WOUDC)

Ozone maps from WOUDC


NASA Ozonewatch

DLR World Data Centre for Remote Sensing of the Atmosphere (WDC-RSAT)

NOAA-NCEP: Meteorological Conditions and Ozone in the Polar Stratosphere

British Antarctic Survey: Jonathan Shanklin's web site with data in near-real time

CNRS, Service d'Aéronomie, Web site with SAOZ data in near-real time

NOAA/ESRL Global Monitoring Division's Home Page (data from South Pole and other stations)

Brewer data from the Argentine station Marambio (maintained by the Czech Hydrometeorological Inst.)

Ground based and satellite data from the University of Bremen

Data from the Microwave Limb Sounder (MLS) on the AURA Satellite

UV data from Dirección Meteorológica de Chile

Data on ozone and UV radiation from the Antarctic Network of NILU-UV radiometers

UV and ozone web site of NIWA with UV Index forecasts

TOMS and OMI web site at NASA

University of Cambridge Ozone Hole Tour






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