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Environment Canada

Ozone and UV monitoring

Monitoring of the ozone layer and ultraviolet radiation is performed by Environment Canada, Science and Technology Branch, Atmospheric Science and Technology Directorate, Air Quality Research Division.

Environment Canada scientists, and scientists in many other countries and organizations, measure ozone and UV in several ways. They pool their results, which are collected and turned into maps. All going well, the maps for a day are available by 1500h UTC the following day.

Canadian ozone and UV monitoring

Canada maintains a network of Brewer Ozone Spectrophotometers, which measure the total thickness of the ozone layer (known as “total column ozone”) several times per hour, when the weather permits (i.e. is not so cloudy that the stratosphere can not be seen).

In addition, balloons carrying ozonesondes are launched, usually once per week, into the stratosphere, which measure the altitude of the ozone layer above the surface of the earth.

  • Most recent Brewer observations

    This page shows the most recent measurements of the ozone layer and UV index, as measured by Brewer Ozone Spectrophotometers in the Canadian network. The page is updated every five minutes.

  • Ozone forecast

    The forecast of the ozone layer over Canada today. There are two maps of Canada, one showing the absolute thickness of the ozone layer, and the other showing the thickness compared to normal for this day of the year. The page is updated every day.

  • Current Ozone Maps over Canada

    Maps of Canada showing the ozone layer as it was yesterday and the day before. These maps are updated every day.

  • Realtime maps

    Maps of the ozone layer over Canada, from measurements taken today. The page is updated every hour.

  • Year-to-Date Total Ozone Graphs

    The ozone layer as measured by Brewer Spectrophotometers for the year to date. Presented as time-series graphs. The page is updated every day.

  • Year-to-Date Ozonesonde Graphs

    The ozone layer as measured by ozonesonde instruments suspended from balloons for the year to date. Presented as three-dimensional time-series graphs with the third dimension shown by colour. The page is updated when ozonesonde flights take place, which is generally every Wednesday.


UV index information

Canada maintains a network of Brewer Ozone Spectrophotometers, which measure the UV index several times per hour during daylight hours. During nighttime hours, including the Polar Night, the UV index is always zero.

When the sky is clear, it is possible to calculate what the UV index will be at any place on the earth, any day of the year, and any time of the day, given a few assumptions. A calculator is provided.

  • UV index today in Canada

    The UV index measured today by Brewer Spectrophotometers in the Canadian network. Presented as time-series graphs. This page is updated every five minutes.

  • Year-to-Date Daily Maximum UV Index Graphs

    The maximum daily UV index measured by Brewer Spectrophotometers in the Canadian network for the year to date. Presented as time series graphs showing three types of information. Thie graphs are updated every day.

  • Year-to-Date UV Index Graphs

    The UV index measured by Brewer Spectrophotometers in the Canadian network for the year to date. Presented as three-dimensional graphs, with the x-axis being day of the year, the y-axis being time of the day, and the UV index for each day and time being shown as a colour. This page is updated every day.

  • UV Index Calculator

    You are presented with a map of the world, from which you click on a location. It shows you a time-series graph of the maximum (noon) UV index for each day of the year at that location. Then you can click on a date on the graph and it gives you another graph showing how the UV index varies during the day. There is a form where you can vary such things as the altitude and the thickness of the ozone layer, which change the UV index.

  • WOUDC - The World Ozone and Ultraviolet Radiation Data Centre

    The World Ozone and Ultraviolet Radiation Data Centre (WOUDC) is an official WMO (World Meteorological Organization) repository for measurements of UV radiation. It is managed by Environment Canada personnel.


World ozone

Environment Canada scientists work with scientists in many other countries and organizations. The World Meteorological Organization has assigned them to manage the World Ozone and Ultraviolet Radiation Data Centre, and through it a World Ozone Mapping Centre.

  • Ozone map archive

    The archive of ozone-layer maps of the Northern Hemisphere, Southern Hemisphere or the Earth, either as an absolute thickness, or compared to the normal for that day of the year, for every day since 1970. These maps are a blend of observations from several sources. This archive is updated every day.

  • Ozone maps, individual sources

    Similar to the Ozone Map Archive, but maps are prepared from individual measurement sources. This archive is updated every day.

  • Recent Ozone Maps

    Maps of yesterday and the day before of the thickness of the ozone layer over the Northern Hemisphere, or Southern Hemisphere, or the Earth. Shown as absolute amounts, or deviation from normal for the day of the year. This archive is updated every day.

  • Maps of normal ozone

    Maps of the Northern Hemisphere, Southern Hemisphere and the Earth, showing the normal (i.e. average) thickness of the ozone layer for each month of the year.

  • WOUDC - The World Ozone and Ultraviolet Radiation Data Centre

    The World Ozone and Ultraviolet Radiation Data Centre (WOUDC) is an official WMO (World Meteorological Organization) repository for measurements of stratospheric ozone. It is managed by Environment Canada personnel.



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