Wave Mode Occurrence Distribution Around Venus: A VEX Statistical Study

Abstract

In this work, plasma and magnetic field data from Venus Express (VEX) were analyzed through the entire mission span (2006-2014) in order to statistically study wave mode occurrence around Venus considering different solar wind conditions. The wave mode occurrence distribution in terms of solar activity (maxima and minimum periods), solar wind pressure, and interplanetary magnetic field (IMF) east-west component orientation (By>0 and By<0) were computed. Our results reveal that mirror mode occurrence does not seems to be affected by changes in the analyzed parameters. The most significant influence was observed in the Alfvén mode by the solar wind dynamic pressure, which has its occurrence rate clearly increased, during periods of high solar wind dynamic pressure. The fast mode seems to be influenced by the three analyzed parameters and tends to occur more often during periods of positive IMF By and high solar activity. Further, a higher occurrence of fast wave mode during enhanced dynamic pressure was observed, which may be related to KH instability.