Effect of transient solar wind pulses on atmospheric heating at Jupiter

TL;DR

This study investigates how transient solar wind pulses impact Jupiter's atmospheric heating and auroras, revealing significant increases in thermospheric heating, temperature, and auroral emissions during such events.

Contribution

It is the first to model and analyze the effects of transient solar wind events on Jupiter's thermosphere and auroras using a coupled global circulation and magnetosphere model.

Findings

Transient events cause at least a twofold increase in Joule heating.

Main oval UV emissions increase by up to 4.5 times during compressions.

Temperature variations of at least 25 K occur locally in the thermosphere.

Abstract

Previously, we have presented the first study to investigate the response of the Jovian thermosphere to transient variations in solar wind dynamic pressure, using a coupled, azimuthally symmetric global circulation model coupled with a simple magnetosphere model. This work (Yates et al., 2013, submitted) described the response of thermospheric flows, momentum sources, and the magnetosphere-ionosphere coupling currents to transient compressions and expansions in the magnetosphere. The present study describes the response of thermospheric heating, cooling and the auroral emissions to the aforementioned transient events. We find that transient compressions and expansions, on time scales <= 3 hours, cause at least a factor of two increase in Joule heating per unit volume. Ion drag significantly changes the kinetic energy of the thermospheric neutrals depending on whether the magnetosphere is compressed or expanded. These processes lead to local temperature variations >= 25 K and a ~2000 TW increase in the total power dissipated in the thermosphere. In terms of auroral processes, transient compressions increase main oval UV emission by a factor of ~4.5 whilst transient expansions increase this main emission by a more modest 37%. Both types of transient event cause shifts in the position of the main oval, of up to 1 deg latitude.