Speaker: Lindsay Goodwin
Location: Physics 175
Time: 3:30, August 21 2014
Abstract: Multi-point in situ measurements from the Swarm spacecraft in a string-of-pearls configuration provide a novel tool to investigate the creation, transport, and evolution of polar cap patches. Swarm observes a sequence of density features being created and structured in the northern Scandinavian dayside cusp by particle impact ionization. These features become entrained in the polar-cap convection pattern, and evolve into lower-density polar cap patches. Equatorward, a long-lived and robust westward flow channel is seen eroding dayside plasma. This channel prevents the dayside solar-ionized plasma from directly entering the cusp precipitation region, but possibly allows for the creation of higher-density plasma further in the polar cap. These are the first observations of a series of patches entrained in the polar cap flow, on the way from their source (the cusp) to the nightside auroral oval.
Speaker: Ashton Reimer
Location: Physics 175
Time: 3:30pm, May 29, 2014
(Updated): Here is a link to the presentation here.
Abstract: Since Christian Hülsmeyer’s first use of radio waves to detect distant objects, radio detection and ranging or radar has expanded across many technological and scientific fields. This talk will focus on radar as it is used to probe the plasma environment of the upper atmosphere. An introduction to some of the radar theory and physical operation of the radars will be followed with a brief discussion of my PhD thesis work with the Canadian SuperDARN radars.
Speaker: Landon Rieger
Location: Physics 175
Time: 3:30pm, May 22, 2014
(Updated): A pdf of Landon’s talk can be found here.
Abstract: Solving underdetermined and ill-posed inverse problems is a common theme in geophysics, image processing and many other fields dealing with remote sensing. Although the problems vary widely, many similar techniques are used across disciplines. The OSIRIS aerosol inversion makes use of linear techniques to explore the information content of the measurements and sensitivity to various retrieved quantities. This information is used to develop a non-linear inversion technique to retrieve stratospheric aerosol profiles.
Congratulations to Gareth Perry for being awarded a PEGASUS travel scholarship to attend the 2013 Canadian American Mexican Graduate Student Physics Conference (CAM) in Waterloo, Ontario, Canada! Gareth is currently working on his PhD in Space Physics in the Institute for Space and Atmospheric Studies.
Gareth presented some interesting observations regarding plasma patches in the polar ionosphere. You may find a copy of his presentation here.
Who (supervisor): Gareth Perry (J.P. St. Maurice)
Venue: PEGASUS Student Summer Seminar, July 12, 2012.
The spatial and temporal evolution of an F-region plasma patch, detected over Resolute Bay, has been studied with a suite of instruments. For this case study, the Resolute Incoherent Scatter Radar – North (RISR-N) is used to construct a three-dimensional image of the plasma parameters of the patch. Three Super Dual Auroral Radar Network (SuperDARN) systems along with optical imagers at Resolute Bay and Qaanaaq, Greenland are used to provide a multi-instrument overview of the both the patch and the high latitude F region during the event. SuperDARN was used to track the patch for nearly an hour, from the cusp region to Resolute Bay. During a 10 minute period, the patch was detected and identified in the RISR-N, Optical Mesosphere Thermosphere Imagers (OMTI) and SuperDARN instruments, yielding a unique opportunity to study the patch with multiple instruments. Of the more interesting findings of this study, one indicates significant density fluctuations within the patch, without any clear evidence for an external driver such as precipitation. The techniques and results of this case study will be described in this presentation, along with the insight which they provide to patch research. Also, a brief introduction to space physics will be given.
Who (supervisor): Landon Reiger (Adam Bourassa)
Venue: PEGASUS Student Summer Seminar, May 31, 2012.
Limb scattered sunlight measurements made by the Optical Spectrograph and InfraRed Imaging System (OSIRIS) onboard the Odin satellite are used to retrieve vertical profiles of ozone, NO2 and aerosol extinction. The retrievals are performed through forward modelling of the atmosphere using SASKTRAN, a fully spherical, successive orders radiative transfer model developed at the University of Saskatchewan. The current aerosol extinction data product is retrieved using an assumed lognormal particle size distribution for typical background conditions. This assumption can produce a systematic error in the result for cases where the size distribution is affected by volcanic aerosol. This work explores the feasibility of retrieving particle size distribution parameters directly from the measurements. Explored here is the possibility of using both multi-spectral extinction and coincident measurements at different scattering angles, obtained on the ascending and descending portions of the orbit, to retrieve particle size information. These results will be used to improve the current aerosol extinction retrieval.