The interaction between ULF waves and thermal plasma ions at the plasmaspheric boundary layer during substorm activity

The interaction between ULF waves and thermal plasma ions at the plasmaspheric boundary layer during substorm activity Jie Ren¹([email protected]),Qiugang Zong¹,Yongfu Wang¹,Xuzhi Zhou¹

¹School of Earth and Space Sciences, Peking University, 100871 Beijing, China

During a substorm on 27 January 2004, energetic particle injections associated with ULF waves have been detected when Cluster fleet was travelling inbound in the southern hemisphere. Substorm injected energetic particles are strong and clearly modulated by these ULF waves. The ULF waves with the period of 1 minutes are probably the third harmonic mode. The periodic pitch angle dispersion signatures at 5.2-6.9 keV energy channel were detected by Cluster satellite. These thermal plasma have high coherence with the electric field of the third harmonic poloidal mode, and satisfy the drift-bounce resonant condition of N="2." In addition, ion outflows from the Earth’s ionosphere (tens to hundreds of eV) are also observed to be modulated by these ULF waves. To the best of our knowledge, this is the first report to show that ULF waves can simultaneously interact with both substorm injected "hot" particles from the magnetotail and cold outflow ions from the Earth's ionosphere.

This work was supported by National Natural Science Foundation of China (41421003) and Major Project of Chinese National Programs for Fundamental Research and Development (2012CB825603). The data for this paper are avaliable at Cluster Active Archive (http://caa.estec.esa.int/caa/home.xml) and Cluster Science Archive (http://www.cosmos.esa.int/web/csa). We acknowledge Geoff Reeves ([email protected]) for providing LANL geosynchronous electron data. The authors most gratefully acknowledge many useful discussions with A.T.Y. Lui, R. Rankin and A.W. Degeling.

Ren, J., Zong, Q. G., Wang, Y. F. and Zhou, X. Z. (2015), The interaction between ULF waves and thermal plasma ions at the plasmaspheric boundary layer during substorm activity. J. Geophys. Res. Space Physics, 120: 1133–1143. doi:10.1002/2014JA020766.