One to 10Day Forecasts of Ionospheric Total Electron Content Using a Statistical Model
Journal Article - Open Access
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
Pagination or Media Count:
A new, rapid, nonassimilative technique is demonstrated for forecasting the ionospheres vertical total electron content TEC on time scales longer than 1 day. The approach uses a statistical model constructed by regressing solar extreme ultraviolet irradiance and seasonal, diurnal, and geomagnetic predictors at multiple lags against the 2-hourly International Global Navigation Satellite Systems Service observations, with a formulation that accounts for solar modulation of the seasonal oscillations and solar and seasonal modulation of the diurnal oscillations. Solar irradiance inputs to the statistical model are forecast at successive 2-hr intervals from 1999 to 2015 using an autoregressive model of irradiance variations during the prior 100 days. As the forecast time increment increases from 1 to 10 days, the average over the globe of the mean absolute error of TEC observations and the forecasts increases from 2.5 to 3.2 TECU total electron content unit, 1 TECU 1016 elm2 the root-mean-square error increases from 3.7 to 4.8 TECU. Averaged over the equatorial ionization anomaly region 30 degrees S-30 degrees N the mean absolute error of the forecasts increases from 3.2 to 4.3 TECU and the root-mean-square error increases from 4.6 to 6.4 TECU. The skill of the TEC forecasts at time increments of 3, 5, and 8 days ahead exceeds persistence by 9 , 13 , and 15 and climatology by 9 , 12 , and 10 , respectively. Forecast skill is higher in April than in July. Long-range, multiyear forecasts from 2018 to 2030 are demonstrated based on current expectations that solar activity in cycle 25 will be comparable to that in cycle 24.
- Atmospheric Physics