Prediction of relativistic electron flux at geostationary orbit following storms: Multiple regression analysis

Abstract

Many solar wind and magnetosphere parameters correlate with relativistic electron flux following storms. These include relativistic electron flux before the storm; seed electron flux; solar wind velocity and number density (and their variation); interplanetary magnetic field B z , AE and Kp indices; and ultra low frequency (ULF) and very low frequency (VLF) wave power. However, as all these variables are intercorrelated, we use multiple regression analyses to determine which are the most predictive of flux when other variables are controlled. Using 219 storms (1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002), we obtained hourly averaged electron fluxes for outer radiation belt relativistic electrons (>1.5 MeV) and seed electrons (100 keV) from Los Alamos National Laboratory spacecraft (geosynchronous orbit). For each storm, we found the log 10 maximum relativistic electron flux 48-120 h after the end of the main phase of each storm. Each predictor variable was averaged over the 12 h before the storm, the main phase, and the 48 h following minimum Dst. High levels of flux following storms are best modeled by a set of variables. In decreasing influence, ULF, seed electron flux, Vsw and its variation, and after-storm B z were the most significant explanatory variables. Kp can be added to the model, but it adds no further explanatory power. Although we included ground-based VLF power from Halley, Antarctica, it shows little predictive ability. We produced predictive models using the coefficients from the regression models and assessed their effectiveness in predicting novel observations. The correlation between observed values and those predicted by these empirical models ranged from 0.645 to 0.795.

ULF wave power index for space weather and geophysical applications: A review

“…The daily maximum relativistic electron flux at geostationary orbit was attempted to predict with a set of variables including previous day's flux −1, seed electron (∼ 100 keV) flux, SW velocity and density, index, IMF , , and ground ULF and VLF wave power [Simms et al, 2014]. As predictor variables are intercorrelated, used multiple regression analyses to determine which are the most predictive of flux when other variables are controlled.…”

“…As many of these factors are correlated among themselves, Simms et al [2014] developed model that attempted to determine which of these factors correlated with and predicted flux best. However, Simms et al…”

Relativistic electrons of the outer radiation belt and methods of their forecast (review)

“…//www.swpc.noaa.gov/products/Relativistic-Electron-forecast-the model] to 26 [Simms et al, 2014]. As forecasting A.S.…”

“…As forecasting A.S. Potapov 62 methods researchers most often employ linear filters [Baker et al, 1990], formed on the basis of the multivariate analysis [Simms et al, 2014[Simms et al, , 2016, in particular using the Kalman filter [Sakaguchi et al, 2015], as well as nonlinear methods such as neural networks Wide et al, 2016] and nonlinear autoregressive moving average modeling (NARMAX) [Balikhin et al, 2011]. By the lead time, forecasts are divided into short-, medium-, and long-term.…”

“…Unlike other studies relying on the multivariate statistical analysis [Simms et al, 2014[Simms et al, , 2015[Simms et al, , 2016Sakaguchi et al, 2015], in this case, there is an additional element in the forecast procedure, which allows us to revise regression coefficients obtained from the preliminary analysis of regression relationships . [Potapov et al, 2014] As predictors we take daily averages of the following parameters: 1) solar wind velocity (V sw ); 2) amplitude of Pc4-5 ULF oscillations as inferred from ground-based (A gr ) and solar wind (A sw ) observations; 3) horizontal component of the magnetic field at geosynchronous orbit (H p ); 4) density of solar wind protons (N p ); 5) solar wind dynamic pressure (p dyn ); 6) interplanetary electric field (E y ); 7) maximum daytime flux J 600 of seed electrons with energy of about 600 keV, measured at geosynchronous orbit.…”