Solar Wind Control of Jets Impacting the Magnetopause

Abstract:

Magnetosheath jets are high dynamic pressure pulses that originate at the quasi-parallel bow shock and propagate Earthward through the magnetosheath. Upon impacting the magnetopause, jets are able to trigger magnetic reconnection and may create space weather effects. It appears, however, that only a small proportion of jets make it to the magnetopause, with most being braked or dissipated in the magnetosheath. New statistical analysis is presented in which we attempt to determine how solar wind conditions upstream of the bow shock can influence the penetrative abilities of jets and the probability of them hitting the magnetopause. Making use of 13,096 jet observations made by the THEMIS spacecraft from 2008 to 2018, we find that low IMF cone angles and high solar wind speeds, amongst other factors, promote the likelihood of both jet occurrence and jet penetration. This is an important first step towards forecasting the space weather effects generated by geoeffective jets.