EMIC waves observed by Cluster at middle magnetic latitudes in the dayside magnetosphere

Electromagnetic ion cyclotron (EMIC) waves are preferably excited in the local regions of minimum magnetic field strength, which is associated with a low characteristic energy for wave-particle cyclotron interactions. The generation and propagation of EMIC waves are also profoundly controlled by plasma properties such as temperature anisotropy of energetic (a few tens of keV) H+, ion composition, total plasma density, and energetic H+ density. From 0348 to 0530 UT on 9 April 2005, Cluster observed intense EMIC wave activity, identified from the wavelet spectrograms of high-resolution (22.4 vectors/second) magnetic field data from the Fluxgate Magnetometer (FGM). The wave event occurred at middle magnetic latitudes (MLAT = 36.3-46.5 deg.) on the dayside (MLT = 10.3-10.4), where L = 10.5-11.0 and the distance from the Earth is in the range of 7.4-8.5 RE. The power spectra of the wave emissions indicate that they are probably originated from two source regions. In this study, we perform a case study to investigate the wave event and associated plasma and geomagnetic conditions such as wave properties, local plasma properties, upstreaming solar wind plasma/interplanetary magnetic field (IMF) parameters, and geomagnetic activity.