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.
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.
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.
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.