The Wave Normal Angle Characteristic of Whistler‐Mode Waves in the Dayside Terrestrial Space Based on MMS Observations

Abstract Wave normal angle (WNA) is an important parameter in the analysis of wave‐particle interactions. The WNA distribution may significantly influence the effective interaction between the waves and solar wind electrons. As a region of direct interaction with the solar wind, the WNA distribution of whistler‐mode waves in the dayside terrestrial space is still unclear. This paper reports statistical work on the WNA distribution of whistler‐mode waves in the dayside terrestrial region. The results show that whistler‐mode waves with quasi‐parallel WNA tend to increase gradually near the magnetopause, while the occurrence rate of oblique waves increases significantly in the magnetosheath with increasing solar wind dynamic pressure . Under the strong condition, the distribution of WNAs both in quasi‐parallel and oblique decreases sharply within the 0.5–0.8 frequency range. Moreover, we find that strong can effectively affect the amplitude of oblique whistler‐mode waves. These results can improve understanding of the kinetic process associated with whistler‐mode waves.