Magnetosphere sawtooth oscillations induced by ionospheric outflow
Brambles, O. J., Lotko, W., Zhang, B., Wiltberger, M., Lyon, J., & Strangeway, R. J. (2011). Magnetosphere sawtooth oscillations induced by ionospheric outflow. Science, 332, 1183-1186. doi:10.1126/science.1202869
The sawtooth mode of convection of Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O⁺ outflows can generate sawtooth oscillations. As t... Show moreThe sawtooth mode of convection of Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O⁺ outflows can generate sawtooth oscillations. As the outflowing ions fill the inner magnetosphere, their pressure distends the nightside magnetic field. When the outflow fluence exceeds a threshold, magnetic field tension cannot confine the accumulating fluid; an O⁺-rich plasmoid is ejected, and the field dipolarizes. Below the threshold, the magnetosphere undergoes quasi-steady convection. Repetition and the sawtooth period are controlled by the strength of the SW-M-I interaction, which regulates the outflow fluence. Show less