Correlation of ULF and Whistler Wave Frequencies Across Mercury’s Bow Shock

This study investigates ultra low frequency (ULF) and whistler waves observed across Mercury's bow shock using magnetic field data from NASA's MESSENGER spacecraft. A total of 240 bow shock crossings from November and December 2011 were analyzed. Dominant frequencies in both the upstream solar wind and downstream magnetosheath were extracted using discrete Fourier transforms. Of these, only 13 crossings exhibited clear and identifiable ULF peaks and 12 whistler peaks suitable for comparison. A Pearson correlation coefficient of 0.697 was found between the upstream and downstream frequencies, indicating a moderately strong positive correlation, while the whistler wave correlation only measured 0.202. These results suggest a partial transmission of wave frequencies through the bow shock for the ULF waves. However, the limited number of usable cases highlights the need for further studies. The findings contribute to a better understanding of magnetic field interactions and wave dynamics in planetary magnetospheres.