Immediate Impact of Solar Wind Dynamic Pressure Pulses on Whistler‐Mode Chorus Waves in the Inner Magnetosphere

• Published in: Geophysical research letters Vol. 49; no. 5
• Main Authors: Jin, Yuyue, Liu, Nigang, Su, Zhenpeng, Zheng, Huinan, Wang, Yuming, Wang, Shui
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 16.03.2022
• Subjects: Amplitudes; Auroral kilometric radiation; Chorus waves; Dynamic pressure; Electron acceleration; Electron precipitation; Geomagnetic field; Geomagnetism; Growth; Inhomogeneity; Magnetism; Magnetospheres; Magnetospheric-solar wind relationships; Modelling; Nonlinear control; Particle dynamics; Pressure; Pressure pulses; Probes; Radiation; radiation belt; Radiation belts; Saturn; Sensors; Solar wind; solar wind disturbances; Solar wind dynamics; solar wind‐magnetosphere coupling; Space weather; wave generation; Waves; wave‐particle interaction; Whistlers
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL097941

Solar wind‐magnetosphere coupling is a key link of the space weather chain. There have been increasing reports of solar wind dynamic pressure pulses influencing the whistler‐mode chorus wave growth in the inner magnetosphere, but the response conditions and mechanisms of chorus growth remain under debate. Here we present a statistical study of the immediate impact of solar wind dynamic pressure pulses on inner magnetospheric chorus waves using Van Allen Probes data from 2012 to 2019. A stronger pulse is found to have a greater likelihood to change the chorus amplitude particularly on the dayside. Positive pulses can significantly enhance chorus amplitudes, while negative ones result in a weakening in chorus amplitudes. As supported by direct observations, these pulses alter the linear growth of waves by modifying energetic electron distributions; in contrast, geomagnetic field modeling indicates no significant changes in the geomagnetic field inhomogeneity controlling the nonlinear growth threshold of waves. Plain Language Summary The geospace environment is highly controlled by the solar wind. In the inner magnetosphere, the whistler‐mode chorus waves, contributing significantly to the radiation belt electron acceleration and the auroral electron precipitation, have been increasingly reported to respond to the solar wind dynamic pressure pulses upstream of the Earth. However, how positive and negative solar wind dynamic pulses affect the inner magnetospheric chorus waves remains under debate. By statistically analyzing and modeling Van Allen Probes data, we show that solar wind dynamic pressure pulses mainly alter the linear growth of waves by modifying energetic electron distributions, with stronger pulses leading to a greater likelihood of causing observable enhancement or weakening in wave amplitudes. The present study contributes to our understanding of the evolution of chorus waves and the chorus‐driven particle dynamics in the inner magnetosphere. Key Points A stronger solar wind pressure pulse has a greater likelihood to change the magnetospheric chorus amplitude particularly on the dayside Positive (negative) pressure pules can immediately increase (decrease) chorus amplitudes in the inner magnetosphere These pulses mainly alter the linear growth of chorus waves by modifying the source electron distributions in the inner magnetosphere