Feb. 19, 2016

The Odin satellite was launched in February 2001 from Svobodny, in eastern Siberia. Originally planned for a two-year mission, it continues to orbit 600 km above Earth, collecting measurements that are extremely valuable for studying climate and long-term changes in the atmosphere.

Canada's instrument – OSIRIS
Canada's Optical Spectrograph and InfraRed Imaging System (OSIRIS) is the optical payload on Sweden's Odin satellite. It works in synergy with Sweden's advanced radiometer and measures atmospheric composition.
Since 2001, OSIRIS has obtained valuable information on the upper atmosphere. It focuses its attention on altitudes from 7 to 90 km—between the highest mountains and the edge of space—and measures concentrations of ozone, aerosols and nitrogen dioxide.
Data provided by OSIRIS helps scientists better understand the impact of human activities and natural phenomena on the environment and climate.

Monitoring signs of climate change from space
Climate change is one of the greatest threats of our time. Space-based instruments like OSIRIS are valuable tools for studying various aspects of the Earth and atmosphere and support evidence-based decision making at the highest levels.
Canada's OSIRIS instrument has been measuring and mapping ozone and detecting aerosols and nitrogen dioxide in the atmosphere since 2001—longer than any other currently operational space instrument. The long duration and consistent quality of OSIRIS measurements are internationally recognized and used to validate and improve climate models worldwide. The resulting datasets have historical value and play an important role in international efforts like the ESA Climate Change Initiative and are used in the Intergovernmental Panel on Climate Change (IPCC) and theWorld Meteorological Organization (WMO) ozone reports, to name a few.

Understanding ozone
Ozone molecules in Earth's atmosphere shield the surface of the Earth from a large percentage of the Sun's harmful ultraviolet rays. Keeping the ozone layer healthy is essential for sustaining life on Earth.
OSIRIS has been providing daily, monthly, and annual measurements of the ozone layer since 2001. The data shows that the ozone layer has been stabilizing gradually since the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer—often described by the international community as one of the most successful international agreements to date. Steady progress has been made under the Protocol: The rate of ozone depletion slowed between 1995 and 2000 and is now showing signs of recovery.

The "ozone hole" continues to appear over the South Pole every spring, but it is no longer getting larger.
Ozone-depleting substances such as chlorine-containing gases react and destroy ozone molecules under the right sunlight conditions. The conditions for extreme ozone destruction, leading to what is commonly known as the "ozone hole," are generally present only during the spring season over the South Pole.
Surprising ozone depletion over the Canadian Arctic
OSIRIS measured an unexpectedly large reduction in ozone over the North Pole for the first time in 2011. The explanation: stratospheric temperatures in the spring allowed chlorine-containing gases to react more strongly and destroy more ozone molecules than usual. Thankfully, such low concentrations have not been observed since.

Aerosols and global cooling
Aerosols also play an important role in Earth's climate, reflecting or absorbing sunlight.
Did you know that a volcanic eruption can lead to a temporary drop in global temperatures?
When a volcano erupts, the concentration of aerosols in the stratosphere increases. These aerosols can remain in the stratosphere for months and even years, causing worldwide temperatures to drop during this period because of the way these tiny particles reflect sunlight.
A real-life example: When the Nabro Volcano erupted in June 2011, OSIRIS measured a significant increase in aerosols, first over Asia but eventually around the Northern Hemisphere, including over Canada. OSIRIS has measured the impact of nine volcanic eruptions like this since the beginning of its mission.

Image:
(A) OSIRIS
(B) Typical seasonal variations of ozone concentration over the South Pole
The left image shows higher concentrations of ozone in February 2015, and the right image shows very low ozone concentrations, the "ozone hole," in October 2015.
(C) The first ozone hole over Canada
On the left, very low ozone concentrations were measured over the North Pole in March 2011. The typical ozone concentration levels measured over Canada in the spring are illustrated in this image from March 2015.

(D) Eruption at Nabro Volcano
The Nabro Volcano, along the border between Eritrea and Ethiopia, emitted a thick plume of volcanic gases on June 15, 2011.
(E) Aerosol concentrations over Canada following the July 2011 Nabro Volcano eruption
This series of images illustrates the changing concentration of aerosols over Canada, as measured by the OSIRIS instrument in 2011 and 2012. From left to right: low concentration of aerosols are measured just before the Nabro eruption; higher concentrations mostly over Asia about a month later; higher concentrations spread throughout the Northern Hemisphere by stratospheric winds two months after the eruption; and finally, after ten months, a return to pre-eruption levels with some residual remaining.