Localized ion outflow in response to a solar wind pressure pulse

Neutrals created by charge-exchange of low-energy (similar to10-100 eV) ion outflow from the ionosphere are imaged by the Low Energy Neutral Atom (LENA) imager on the IMAGE spacecraft. Comparing the neutral flux with changes in the solar wind during an ion outflow event on 24 June 2000 indicates that changes in solar wind density (and therefore dynamic pressure) are associated with episodic bursts of ion outflow. LENA images show that these bursts are confined to the duskside. Simultaneous images of the aurora from the IMAGE FUV Wideband Imaging Camera indicate that these episodic bursts on the duskside are associated with increased duskside auroral emissions. The pitch angle and charge exchange altitude for the ion outflow distributions are estimated by applying field line tracing in a model magnetic field and assuming that the outflow occurs in the auroral zone. The pitch angle information places constraints on the neutral atom images, indicating that the ion outflow observed on the duskside probably consists of high pitch angle conics and that field-aligned ion outflow from other parts of the oval cannot be observed from the IMAGE spacecraft location.