Grant: Discovery Grants Program - Individual

The University of Western Ontario's Purple Crow Lidar (PCL) measures temperature and composition of Earth's atmosphere from the surface to 110 km altitude. The PCL is able to make these measurements at unprecedented accuracy by using a 2.65 m diameter liquid mirror telescope. The liquid mirror is a Canadian technology which allows large mirrors to be built at a fraction of the cost of traditional glass mirrors. The long-term objectives of this research program are to search for atmospheric change and to help improve weather forecasting. The proposed measurements program will look for atmospheric change in three ways. First, PCL temperatures measurements will be used to study temperature change. Temperature change in the middle atmosphere is not directly affected by land, cities or oceans like surface temperature measurements. Second, ozone and water vapor composition change will be measured at both middle and high latitudes. Third, layers of smoke particles at 14 to 16 km altitude associated with forest fires, injected into the stratosphere via a process called pyroconvection, will be investigated. The smoke particles can travel great distances, and affect both ozone and temperature. With the number and severity of forest fires increasing, forest fires play a more complex role in global warming than anticipated, and we are trying to understand these effects. The PCL also measures disturbances in the air density similar to waves on the surface of a lake called gravity waves. These waves break like ocean waves on a beach, primarily at altitudes above 50 km. Remarkably, even waves that break 100 km above the surface play an important role in determining the behaviour of weather systems which affect us on the surface. Furthermore, the gravity waves alter composition and thus affect ozone.