Investigate the Effect of Plasma Density Perturbation on the Hiss Wave Amplitude

Using nine years of plasma density and hiss wave observations from the Van Allen Probes, we have compiled a substantial dataset of time intervals featuring significant plasma density perturbations and hiss wave power. We extracted the upper and lower bounds of the plasma density variation as well as the hiss amplitude variation. Statistical analysis shows that the density difference (ΔlogN) has a strong positive correlation with both the hiss amplitude (logA) and the hiss amplitude difference (ΔlogA), indicating the modulation effect of plasma density on the hiss wave amplitude.

Using machine learning techniques, we developed a regression model to predict the hiss amplitude (logA and ΔlogA) from plasma density information, spatial position, and geomagnetic indexes. The modeling results show that incorporating the density difference ΔlogN into the model improves prediction accuracy. Feature importance analysis indicates that ΔlogN is the most important feature for predicting the hiss amplitude difference ΔlogA.