Improved Empirical Models of Plasmaspheric Hiss Intensity and Spectral Distribution

Abstract:

Plasmaspheric hiss is a whistler mode emission that permeates the Earth’s plasmasphere and is a significant driver of energetic electron losses through cyclotron-resonant pitch angle scattering. The EMFISIS instrument on the Van Allen Probes mission provides vastly improved measurements of the hiss wave environment including continuous measurements of the wave magnetic field cross-spectral matrix and enhanced low frequency coverage. Here, we develop empirical models of hiss wave intensity and spectral distribution using two years of Van Allen Probes data. First, we describe the construction of the hiss database. Then, we compare the hiss spectral distribution and integrated wave amplitude obtained from Van Allen Probes to those previous extracted from the CRRES mission. We present new models of the hiss frequency distribution that extend to lower frequency than conventional models of hiss. Next, we develop a multiple regression model of the average hiss magnetic field intensity as a function of Kp, L, magnetic latitude and magnetic local time. We use the full regression model to explore general trends in the data and use insights from the model to develop a simplified model of wave intensity for straightforward inclusion in quasi-linear diffusion calculations of electron scattering rates.