Forecasting GOES 15 >2 MeV Electron Fluxes From Solar Wind Data and Geomagnetic Indices

Abstract

The flux of > 2 MeV electrons at geosynchronous orbit is used by space weather forecasters as a key indicator of enhanced risk of damage to spacecraft in low, medium, or geosynchronous Earth orbits. We present a methodology that uses the amount of time a single input data set (solar wind data or geomagnetic indices) exceeds a given threshold to produce deterministic and probabilistic forecasts of the >2 MeV flux at GEO exceeding 1,000 or 10,000 cm−2 s−1 sr−1 within up to 10 days. By comparing our forecasts with measured fluxes from GOES 15 between 2014 and 2016, we determine the optimum forecast thresholds for deterministic and probabilistic forecasts by maximizing the receiver‐operating characteristic (ROC) and Brier skill scores, respectively. The training data set gives peak ROC scores of 0.71 to 0.87 and peak Brier skill scores of −0.03 to 0.32. Forecasts from AL give the highest skill scores for forecasts of up to 6 days. AL, solar wind pressure, or SYM‐H give the highest skill scores over 7–10 days. Hit rates range over 56–89% with false alarm rates of 11–53%. Applied to 2012, 2013, and 2017, our best forecasts have hit rates of 56–83% and false alarm rates of 10–20%. Further tuning of the forecasts may improve these. Our hit rates are comparable to those from operational fluence forecasts, that incorporate fluence measurements, but our false alarm rates are higher. This proof‐of‐concept shows that the geosynchronous electron flux can be forecast with a degree of success without incorporating a persistence element into the forecasts.

Deep Neural Networks With Convolutional and LSTM Layers for SYM‐H and ASY‐H Forecasting

“…For example, SYM‐H index is used by Forsyth et al. (2020) to construct forecasts of the >2 MeV flux or by Tshisaphungo et al. (2018) to model the ionospheric F2 layer (foF2) changes during geomagnetic storms.…”

“…Indeed, both Dst and SYM-H are proxies of the symmetric ring current, while the longitudinally asymmetric part of geomagnetic disturbance field at low latitude to midlatitude is quantified by ASY indices (Iyemori, 1990;Iyemori et al, 1992). For example, SYM-H index is used by Forsyth et al (2020) to construct forecasts of the >2 MeV flux or by Tshisaphungo et al (2018) to model the ionospheric F2 layer (foF2) changes during geomagnetic storms.…”

Evaluating Auroral Forecasts Against Satellite Observations

“…ROC and reliability analysis are standard methods used in forecast verification by the weather community (e.g., Dube et al, 2017). They have been used to evaluate flare forecasts from the Met Office Space Weather Operations Centre (MOSWOC) in studies by Murray et al (2017) and Sharpe and Murray (2017), to evaluate the performance of a new radiation belt forecast model (Forsyth et al, 2020) and to assess a sudden storm commencement probabilistic forecast model (Smith et al, 2020).…”

“…Binary event analysis is a method of comparing model forecasts with a ground-truth observational data set and is widely used in many applications. The approach of using binary event analysis has been applied to evaluate nowcast and forecast models, for example, in the verification study of OP-2010 by Machol et al (2012) and verification studies of other space weather models including predicting magnetopause crossings (Lopez et al, 2007;Welling & Ridley, 2010), radiation belt models (Forsyth et al, 2020;Ganushkina et al, 2015Ganushkina et al, , 2019, temporal changes in the induced ground magnetic field ( / ) dB dt (Pulkkinen et al, 2013), and solar flare forecasts (Barnes et al, 2016;Kubo et al, 2017;Leka et al, 2019;Murray et al, 2017;.…”

The ionospheric condition and GPS positioning performance during the 2013 tropical cyclone Usagi event in the Hong Kong region

“…Figure 5c shows the variation of E2 electron fluxes from 13 September 2013 and 11 October 2013. During this TC period, as denoted by the period of two vertical red dashed lines, it started to increase on 19 September and kept a high value larger than 1000 cm −2 s −1 sr −1 between 20 and 24 September, which would affect the operation of spacecraft systems (Forsyth et al 2020). However, the reason for this high electron flux cannot be easily attributed to the solar radiations and geomagnetic activities, because other indices, including Kp, Dst, F10.7, X-ray Time series of X-ray (a), solar X-ray flare count (b), and electron flux (c) during the period from 13 September to 11 October 2013, which were measured by the GOES 15 geostationary satellite.…”