The Ionospheric Data Assimilation Four-Dimensional (IDA4D) technique has been coupled to Sami3 is Another Model of the Ionosphere (SAMI3). In this application, ground- and space-based GPS Total Electron Content (TEC) data have been assimilated into SAMI3, while in situ electron densities, autoscaled ionosonde NmF2 and reference GPS stations have been used for validation. IDA4D/SAMI3 shows that Night-time Ionospheric Localized Enhancements (NILE) are formed following geomagnetic storms in November 2003 and August 2018. The NILE phenomenon appears as a moderate, longitudinally extended enhancement of NmF2 at 30-40o N MLAT, occurring in the late evening (20-24 LT) following much larger enhancements of the equatorial anomaly crests in the main phase of the storms. The NILE appears to be caused by upward and northward plasma transport around the dusk terminator, which is consistent with eastward polarization electric fields. Independent validation confirms the presence of the NILE, and indicates that IDA4D is effective in correcting random errors and systematic biases in SAMI3. In all cases, biases and root-mean-square errors are reduced by the data assimilation, typically by a factor of 2 or more. During the most severe part of the November 2003 storm, the uncorrected ionospheric error on a GPS 3D position at 1LSU (Louisiana) is estimated to exceed 34 m. The IDA4D/SAMI3 specification is effective in correcting this down to 10-m.

An empirical model of radiation belt relativistic electrons (m = 560–875 MeV G–1 and I = 0.088–0.14 RE G0.5) with average energy ~ 1.3 MeV is developed. The model inputs solar wind parameters (velocity, density, interplanetary magnetic field (IMF) |B|, Bz, and By), magnetospheric state parameters (SYM-H, AL), and L*. The model outputs radiation belt electron phase space density (PSD). The model is operational from L* = 3 to 6.5. The model is constructed with neural network assisted by information theory. Information theory is used to select the most effective and relevant solar wind and magnetospheric input parameters plus their lag times based on their information transfer to the PSD. Based on the test set, the model prediction efficiency (PE) increases with increasing L*, ranging from –0.043 at L* = 3 to 0.76 at L* = 6.5. The model PE is near 0 at L* = 3–4 because at this L* range, the solar wind and magnetospheric parameters transfer little information to the PSD. This baseline model complements well a class of empirical models that input data from Low Earth Orbit (LEO). Using solar wind observations at L1 and magnetospheric index (AL and SYM-H) models solely driven by solar wind, the radiation belt model can be used to forecast PSD 30–60 min ahead.

The equatorial ionosopheric anomalies (EIA) at night are the slowly recombining remnants of the dayside ionosphere, and charged particle densities slowly decay during the course of the night. Thus the electron density in ionosphere in the early morning (0300-0400 Local time) is usually very low and the ionospheric UV 135.6 nm O+ recombination emission is rarely detectable from current UV remote sensing instruments. However, there are times when the EIA have unusually high density even during these morning times and are observable by the DMSP/SSUSI and TIMED/GUVI instruments. By using other UV ‘colors’ - 130.4 nm (from monatomic Oxygen) and N2 Lyman Birge Hopfield bands - we can establish that this emission is definitely from the ionosphere recombination emission. We will show examples of this phenomenon, and correlate these occurrences to geomagnetic storm events. We estimate the electron density in the early morning EIA and compare with other ionosphere observations and climatological models. In the figure below, we show the 135.6 nm radiance seen by DMSP F16 SSUSI as it crosses the equator around 210 degrees longitude (over the Pacific Ocean) at 03:45 local time. The equatorial anomaly peaks are clearly visible in the SSUSI data. These radiances are background subtracted, which is not perfect and introduces a small (-1 Rayleigh) bias to the resulting radiances. DMSP = Defense Meteorological Satellite Program, SSUSI = Special Sensor Ultraviolet Spectrographic Imager; TIMED = Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics, GUVI = Global UltraViolet Imager