Modeling of microburst electron precipitation using pitch angle diffusion theory

Microburst electron precipitation is characterized by short bursty (duration similar to 0.2-0.3 s) quasiperiodic precipitation of electrons in the dayside auroral zone. Pitch angle diffusion of electrons due to the interaction with whistler waves has been suggested previously as a possible mechanism for scattering electrons into the loss cone to cause microburst precipitation. In this paper we investigate the viability of the above mechanism through modeling. We assume the scattering to occur near the equatorial plane and solve the pitch angle diffusion equation numerically to find the time-dependent form of the electron distribution function F, which results from a given time-dependent diffusion coefficient D. Different aspects of our results (burst size, pitch angle dependence, risetime, burst width) are compared with observations from a recent rocket experiment on microburst launched from Poker Flat, Alaska. The comparison shows very good agreement, further supporting the idea that the pitch angle diffusion process is the driving mechanism for microbursts.