The neutral atmosphere of planet Earth below 100 km is the research domain of Doug Degenstein, Adam Bourassa, Ted Llewellyn(Emeritus) and Alan Manson(Emeritus), who use a mixture of ground-based and space-borne instrumentation, along with models and general circulation (GCM)models to obtain information relating to the processes in the upper troposphere here - upper troposphere lower stratosphere (UTLS) and the Middle Atmosphere (15-100km). The composition there is controlled by energy from the sun, by chemical activities on the ground, and by the dynamical exchange-processes that 'move' the constituents around.

Ozone Depletion

Atomic oxygen, which is essential to the formation of ozone, is formed in the upper atmosphere, from the photodissociation of molecular oxygen, and then transported downward, where it is eventually converted to ozone. Control over the quantity of ozone in the atmosphere occurs in both the region of maximum concentration, where it is attacked by chemicals resulting from human activity, and in the high atmosphere (>100 km) far removed from the `biological shield'. It is the significant reduction in the ozone column that occurs In late winter (related to "Sudden Stratospheric Warmings" (SSW) and in early spring that has provided direct evidence for the impact of human activities on the atmosphere. However, the full details of the processes for ozone-loss, and those which control global warming are still not adequately understood.

Infra Red Aeronomy and Atmospheric Remote Sensing

One way to improve our measurement database and understanding of those processes responsible for ozone deletion and global change is through the development of new and improved satellite-borne remote sensing instrumentation. The OSIRIS instrument onboard the Odin spacecraft measures vertical profiles of spectrally dispersed, limb scattered sunlight from the upper troposphere into the lower mesosphere.  OSIRIS has been in standard operation since November 2001 and routinely produces height profiles of O3, NO2 and stratospheric aerosols.  These products have been used to investigate the effects of volcanic eruptions on climate, the long term trends in changes in the ozone layer, and the physics and chemistry of the mesosphere.  The OSIRIS instrument concept (and the related atmospheric science) was developed by the ISAS "Infra Red Aeronomy Group" led by Ted Llewellyn.

Atmospheric Dynamics

The wind and weather systems that transport ozone and other GHG (Green House Gases) into the High Arctic, while determining the annual Polar Vortex structures, provide the isolated northern polar environments for the late winter (SSW) and spring-time destruction of ozone.  These are observed and studied with ISAS's ground based radars and the highly sophisticated spectrograph and IR imager of OSIRIS. The three MF radars of Alan Manson's "Atmospheric Dynamics Group" at Saskatoon, Platteville and Tromso, as well as the Meteor Winds Radar at Eureka 80N, Ellesmere Island, measure atmospheric motions from 60-100 km and provide data for the background winds and atmospheric tidal, planetary, and gravity waves. Such waves re-distribute solar energy, and energy associated with weather systems, throughout the entire earth's atmosphere, which stretches from the ground to over 100 km and includes equatorial structures and the "Polar Vortex" of the winter's northern latitudes. These ISAS radars are part of a growing global network of wind sensors, and tell us much about the controlling processes for climate change. Satellite optical interferometers (eg.  WINDII, TIDI) measure wind speed and direction by looking at the change in the colour of light (Doppler effect). The combination of high resolution spatial and temporal observations, provided by satellite and ground-based systems, is very synergistic.  Already we know that equatorial processes modify the "Polar Vortex", which is the dominant thermal and wind system for middle to polar latitudes during winter and adjacent equinoctial months.

Global Studies of Climate Change

Collaborations within programs such as the new 2014 international VarSITI program (Variablilty of the Sun and Its Terrestrial Impact) within SCOSTEP (Scientific Committee on Solar Terrestrial Physics) and SPARC (a project of the "World Climate Research Program") allow processes of 'Climate Change' to be studied globally. The new "Probing the Atmosphere of the High Arctic" (PAHA) Program (2013-2017 within NSERC's new "Climate Change and Atmospheric Science" Program, is centred on PEARL [Eureka 80N], and includes an ISAS-led project on the "Polar Vortex".  Led by Alan Manson, studies already show that disturbances in the structure of the Polar Vortex during the winters of 2012/13 and 2013/14 are leading to strong outflows of frigid Arctic air over Canada, USA and Europe, throughtout the winter season (November-March)...causing dangerous and "unseasonable" wind, snow and ice conditions, with human and livestock deaths and injuries along with interference in travel and commercial activity.  Collaborations with Environment Canada's Meteorological Service are focused upon incorporating these proecesses into Weather Forecasts of expanded duration using their GEM numberical model.  Many of these dynamical processes have dimensions which are hemispheric or global. It is also vital to investigate trends in ozone concentration, temperature, and atmospheric dynamics which are occurring over time scales longer than solar cycles (about 11 years), and which also contribute to "Global Climate Change".