Space Science Seminar: Particle Precipitation into the Polar Atmosphere

Professor Craig Rodger, Department of Physics, University of Otago, New Zealand

Tuesday 10 March 2015, 1600-1700
Bowland North Seminar Room 20

The space around the Earth is filled with fast moving particles trapped in two "belts" by our magnetic field. The belts were named the "Van Allen radiation belts" in 1958 honour of their discoverer, James Van Allen. Earth-orbiting satellites can be damaged or even lost due to increased high-energy electron fluxes in the Earth's radiation belts. Electron fluxes are highly variable, with fluxes changing by many orders of magnitudes on time-scales of hours to days, due to competing acceleration and loss processes. In August 2012 NASA launched a two spacecraft mission specifically focused on improving our understanding of radiation belt physics as part of a US$680 million research programme.

There is increasing international interest in losses from the Van Allen belts. Some of this comes from the community focused on radiation belt physics, trying to understand the fundamental processes occurring in the belts. However there are also complementary questions in ionospheric, atmospheric and climate science as to the importance of energetic electron loss, termed precipitation, into the polar atmosphere. There is a growing scientific realisation that atmospheric changes due to these electrons may be "significant" - leading to important changes in the chemical makeup and dynamics of the upper atmosphere, as well as suggestive studies showing links to polar surface temperatures, i.e. polar climate. In this talk I will give an overview on this research area, and focus particularly on our efforts to quantify the time-varying energetic electron precipitation fluxes.