Limb sounding upper tropospheric and stratospheric trends and processes

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Over the last decade there have been great advances in atmospheric science that have been made possible by new satellite instruments that take measurements of a high altitude region of the atmosphere, called the stratosphere, using a side-view technique called limb-sounding. These advances have improved our understanding of both short term weather related processes and long term climate related processes. Canada has played an important role through the operation of the Canadian-built OSIRIS satellite instrument. The projects funded by this proposal make further use of the OSIRIS measurements to study long term trends in the make-up of the stratosphere as well as processes that occur on much shorter time scales, such as the effects of large volcanic eruptions. We also propose to continue to develop the technology, both hardware and knowledge-based, for new satellite instrumentation using this limb sounding technique for measuring the stratosphere. One of the important atmospheric parameters in this work is stratospheric aerosol. These tiny droplets, which can last in the stratosphere for many years, are caused in part by volcanic eruptions and by scattering sunlight away from the Earth, cool the planet. We will work with multiple satellite measurements to reconcile the global distributions of aerosol over the last few decades. These measurements will also help us understand several poorly understood aspects about volcanic eruptions, such as the details of how the plumes evolve throughout the atmosphere. In addition, we will study methods for obtaining improved aerosol and water vapour information from two new satellite instruments that we are developing with the Canadian Space Agency for future missions. Water vapour is a particularly important atmospheric component and its variability in the atmosphere is poorly understood. Finally, we will work on computational models for these satellite measurements that will help us to understand three dimensional effects in the satellite measurements, such as patches of cloud and thin plumes of aerosol. An important impact of this project will be a greatly increased readiness level for future Canadian space technology with the potential to make key advances in atmospheric science, along with advancement in the knowledge of how to best utilize and understand satellite measurements of the atmosphere.