ANCHOR is a novel data assimilation model developed at the U.S. Naval Research Laboratory for nowcasting ionospheric parameters relevant to space weather applications. ANCHOR incorporates electron density observations from ionosondes, Abel inverted radio occultation data, and ground-based GNSS receivers data into a PyIRI driven model background using the Kalman filter technique. The purpose of this study is to validate the estimated model parameters with direct electron density observations from incoherent scatter radars (ISR) at various levels of solar activity. A six year dataset spanning from 2018 to 2024, has been collected from four operating ISRs located at varying latitudes left of the prime meridian: Arecibo, Jicamarca, Millstone Hill, and Poker Flat. The validation includes four distinct events, with two events at low solar activity, one at moderate, and one at high solar activity, each with data coverage from at least two radars. Parameter extraction is achieved using Epstein functions to derive the bottom and topside of the F2 layer after the peak density (NmF2) and altitude (hmF2) have been found. The ISR-extracted parameters are used to directly compare with the model outputs using the root mean square error (RMSE) analysis method. Up to 75% improvement relative to the background model for NmF2 and hmF2 parameters with consistency across all latitudes is found. Additionally, ANCHOR assimilative model was compared to PyIRTAM model, showing a good agreement between the performances of both systems.

Sporadic-E (Es) layers are characterized as thin layers (1-5 km) of enhanced electron density that occur between 90-120 km in altitude. Sporadic E at mid- and low-latitudes has a reasonably well established climatology, while at high latitudes there have been fewer investigations that have characterized the climatology of sporadic E occurrence using altitude resolved measurements. Incoherent scatter radar provides direct altitude resolved measurements of the E-region ionosphere with relatively high altitude resolution. Since 2008, the Poker Flat Incoherent Scatter Radar (PFISR) has been operating in nearly continuous operations through a low duty cycle mode, thus enabling observations of sporadic E. The distinction between Es and auroral precipitation is detectable and is generally associated with the differences in structure height with Es being on average smaller in altitudinal range and shorter time duration. The purpose of this investigation is to present observations of sporadic E derived from this nearly continuous database of alternating code and Barker code PFISR data spanning the years from 2007-2021. We visually identified the sporadic E layers and have found approximately 300 events. We present statistical results of the occurrence, duration, and characteristics of high latitude sporadic E derived from these events. The preponderance of events manifested within 95 to 120 km, typically lasted 1 to 3 hours, and mostly occurred during May through September with observance peaking in July. In addition, the trends indicated a potential disconnect between sporadic-E events and auroral activity, which was previously considered the primary driving force behind high latitude sporadic-E events. The climatology of high latitude sporadic E is an important contribution that must be considered in future high latitude models of the ionosphere.