Citation: | Liu, D., Yao, Z. H., Wei, Y., Rong, Z. J., Shan, L. C., Arnaud, S., Jared, E., Wei, H. Y., and Wan, W. X. (2020). Upstream proton cyclotron waves: occurrence and amplitude dependence on IMF cone angle at Mars — from MAVEN observations. Earth Planet. Phys., 4(1), 51–61.. doi: 10.26464/epp2020002 |
Proton cyclotron waves (PCWs) can be generated by ion pickup of Martian exospheric particles in the solar wind. The solar wind ion pickup process is highly dependent on the “IMF cone angle” — the angle between the solar wind velocity and the interplanetary magnetic field (IMF), which also plays an important role in the generation of PCWs. Using data from 2.15 Martian years of magnetic field measurements collected by the Mars Atmosphere and Volatile Evolution (MAVEN) mission, we have identified 3307 upstream PCW events. Their event number distribution decreases exponentially with their duration. A statistical investigation of the effects of IMF cone angle on the amplitudes and occurrence rates of PCWs reveals a slight tendency of PCWs’ amplitudes to decrease with increasing IMF cone angle. The relationship between the amplitude and IMF cone angle is weak, with a correlation coefficient