Dr. Shepherd is Principal Investigator for Canada’s Wind Imaging Interferometer (WINDII), in orbit on NASA’s Upper Atmosphere Research Satellite (UARS) from September 1991 to September 2003. Using photochemically produced visible region “airglow” emissions as a target, he determines winds and temperatures over the altitude range 80 to 300 km. The emission strength also provides information on the concentration of atomic oxygen, an important constituent in the upper atmosphere. Migrating tides, non-migrating tides and planetary waves are dominant features of the dynamics of this region, and they move the atomic oxygen up and down by as much as 7 km. The non-migrating tides originate in severe weather associated with continental landmasses, and propagate into the upper atmosphere, where WINDII observes them as a pattern of four waves around the Earth. Other unusual features such as polar mesospheric clouds and the impact of solar flares on the atmosphere have been observed. The analysis of the 23 million images collected continues today.

Figure above showing the four waves of a non-migrating tide as seen in the zonal (eastward) wind, appearing strongly to WINDII at 100 km altitude but continuing to propagate upwards to 200 km, on day 221 of 1992.