Replenishment of electrons lost in the south atlantic anomaly by gyroresonant pitch-angle diffusion

Experimental data describing the effect of the South Atlantic anomaly on E⩾ 280 keV electron flux at L = 2 and high B values, are compared to the numerical solution of a pitch-angle diffusion equation with a varying loss cone. The diffusion coefficient needed to explain replenishment of the electrons lost over the anomaly is found to be 3.2 × 10 −2 sec −1 Calculation of the diffusion coefficient due to cyclotron resonant interaction with VLF electro-magnetic waves leads to the conclusion that the observed wave spectral density can yield the needed diffusion coefficient.