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The Rocket Investigation of Current Closure in the Ionosphere (RICCI) sounding rocket mission concept will use the novel deployment of multiple CubeSats as miniature sub-payloads to obtain the first direct in-situ measurement of ionospheric closure currents. These ionospheric currents are critical to understanding the nature of atmosphere-ionosphere-magnetosphere coupling and have relevance to space weather parameters such as ionospheric densities, thermospheric heating, and satellite drag. Previous attempts to measure these ionospheric closure current in-situ have been limited by poor attitude knowledge resulting in large uncertainties in the magnetic field measurement that compromise the ability to measure the gradient of the magnetic field beyond the precision necessary to resolve the current densities. To address this, RICCI uses dedicated star trackers and currently-available CubeSat subsystems to obtain the high-precision attitude knowledge necessary to directly measure these elusive currents.

This study exploits the volumetric sampling capabilities of the Resolute Bay Incoherent Scatter Radar (RISR-N) in collaboration with all-sky imagery and in-situ measurements (DMSP) to examine the i...

We report one of the first comprehensive ground-based investigations of energy transfer rates in the E-region ionosphere compared relative to geomagnetic activity, seasonal effects, and solar activ...

Joule heating deposits a significant amount of energy into the high-latitude ionosphere and is an important factor in many magnetosphere-ionosphere-thermosphere coupling processes. Although the int...

Key Points: 8 • E region energy transfer rates are estimated from PFISR measurements for the 9 first time. 10 • The electromagnetic energy transfer rate and the Joule heating rate are larger in 11 ...

In this study, we present a bottomside model representation to be used by the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM). This model features a new approach to modeling the bottomside electron density; namely, instead of modelling electron density directly, E-CHAIM models the altitude profile of the scale thickness of a single bottomside layer. In this approach, the curvature in the bottomside associated with the E region and F1 layer is represented in the scale thickness domain as a peak function centered at the layer peak altitude. The use of this approach ensures the production of explicitly doubly differentiable bottomside electron density profiles and directly avoids issues known to exist within current standards, such as the International Reference Ionosphere (IRI), which has discontinuities in space, time, and in the vertical electron density gradient. In terms of performance, after removing the impacts of hmF2 and NmF2, the new E-CHAIM profile function generally performs comparably to the IRI, with bottomside TEC from both models within 2.0 TECU (1 TECU = 10 16 e/m 3 ) of observations. More specifically, the E-CHAIM bottomside is demonstrated to outperform the IRI bottomside function in the F region during low solar activity periods with respect to incoherent scatter radar observations. At high latitudes, E-CHAIM tends to outperform the IRI during winter months by between 10% and 40% of NmF2 while being outperformed by the IRI by between 10% and 25% of NmF2 during summer periods, mainly during the daytime at high solar activity.

The southward pointing field of view of the Canadian component of the Resolute Bay Incoherent Scatter Radar (RISR-C) is well suited for observing the ionospheric signatures of flux transfer events and subsequent polar patch formation in the cusp. The fast azimuthally oriented flows and associated density depletions often show an enhanced ion temperature from Joule heating caused by the sudden change in plasma flow direction. The newly formed polar patches are then observed as they propagate through the field-of-views of both RISR-C and RISR-N. In the ionosphere, the electron density gradients imposed in the cusp, and small-scale irregularities resulting from gradient-drift instability, particularly in the trailing edges of patches, cause GPS TEC and phase variations, and sometimes amplitude scintillation. The neutral atmosphere is affected by ionospheric currents resulting in Joule heating. The pulses of ionospheric currents in the cusp launch atmospheric gravity waves (AGWs) causing traveling ionospheric disturbances, as they propagate equatorward and upward. On the other hand, the downward propagating AGW packets can impact the lower atmosphere, including the troposphere. Despite significantly reduced wave amplitudes, but subject to amplification upon over-reflection in the upper troposphere, these AGWs can trigger/release existing moist instabilities, initiating convection and latent heat release, the energy leading to intensification of storms.

We have taken a key step in evaluating the importance of ionospheric outflows relative to electrodynamic coupling in the thermosphere’s impact on geospace dynamics. We isolated the thermosphere’s m...

An examination of the high latitude performance of the bottomside and topside F-layer parameterizations of the NeQuick electron density model is presented using measurements from high latitude ionosonde and Incoherent Scatter Radar (ISR) facilities. For the bottomside, we present a comparison between modeled and measured B2Bot thickness parameter. In this comparison, it is seen that the use of the NeQuick parameterization at high latitudes results in significantly underestimated bottomside thicknesses, regularly exceeding 50%. We show that these errors can be attributed to two main issues in the NeQuick parameterization:(1) through the relationship relating foF2 and M3000F2 to the maximum derivative of F2 electron density, which is used to derive the bottomside thickness, and (2) through a fundamental inability of a constant thickness parameter, semi-Epstein shape function to fit the curvature of the high latitude F-region electron density profile. For the topside, a comparison is undertaken between the NeQuick topside thickness parameterization, using measured and CCIR-modeled ionospheric parameters, and that derived from fitting the NeQuick topside function to Incoherent Scatter Radar-measured topside electron density profiles. Through this comparison, we show that using CCIR-derived foF2 and M3000F2, used in both the NeQuick and IRI, results in significantly underestimated topside thickness during summer periods, overestimated thickness during winter periods, and an overall tendency to underestimate diurnal, seasonal, and solar cycle variability. These issues see no improvement through the use of measured foF2 and M(3000)F2 values. Such measured parameters result in a tendency for the parametrization to produce a declining trend in topside thickness with increasing solar activity, to produce damped seasonal variations, and to produce significantly overestimated topside thickness during winter periods.

Sudden commencement (SC) induced by solar wind pressure enhancement can produce significant global impact on the coupled magnetosphere-ionosphere (MI) system, and its effects have been studied extensively using ground magnetometers and coherent scatter radars. However, very limited observations have been reported about the effects of SC on the ionospheric plasma. Here we report detailed Poker Flat Incoherent Scatter Radar (PFISR) observations of the ionospheric response to SC during the 17 March 2015 storm. PFISR observed lifting of the F region ionosphere, transient field-aligned ion upflow, prompt but short-lived ion temperature increase, subsequent F region density decrease, and persistent electron temperature increase. A global magnetohydrodynamic (MHD) simulation has been carried out to characterize the SC-induced current, convection, and magnetic perturbations. Simulated magnetic perturbations at Poker Flat show a satisfactory agreement with observations. The simulation provides a global context for linking localized PFISR observations to large-scale dynamic processes in the MI system.

Plasma density cavities are correlated with heavy ion outflow where ions are heated transversely by wave particle interactions (WPIs). This paper presents the first result of a 3D ionospheric fluid model that incorporates plasma temperature anisotropies and a phenomenological treatment of WPIs, leading to transversely accelerated ions (TAIs). It is demonstrated that O+ outflow can generate density cavities in the topside ionosphere. With the empirical heating rate applied in a designated heating region on the dayside, the O+ species in the heating region is accelerated upward by the mirror force. The O+ species below the heating region upflows under the parallel pressure gradient force and the parallel electric force. As the O+ species flows upward, the plasma is eroded both below and inside the heating region. Parametric modeling studies show that the depth of density cavities in the upper ionosphere increases as the heating rate increases. The percent change in the density of the cavity relative to the local background density is practically independent of the low-altitude cutoff of the heating region, but the altitude of the relative density minimum moves upward with the increasing altitude of cutoff. The O+ flux is insensitive to the change of the heating rate, while depends strongly on the altitude of cutoff. Using empirical values of the initial heating rate and the height of the low-altitude boundary as input, the ranges of the modeled electron density and the O+ outflow moments are in reasonable agreement with observations of a storm-time density cavity observed by the FAST satellite. The 3D ionospheric model has the potential to be coupled to magnetospheric models for magnetosphere-ionosphere (MI) coupling.

Joint observations of the Rankin Inlet (RKN) and Inuvik (INV) Super Dual Auroral Radar Network (SuperDARN) HF radars and Resolute Bay incoherent scatter radar (RISR) are used to assess consistency in their plasma flow velocity measurements. The analysis covers more than 500 hours of successful concurrent measurements. We demonstrate that, overall, the radars show close velocities, though there were minor differences including SuperDARN velocity underestimation, in line with previous publications, and the persistent occurrence of measurements with a SuperDARN velocity magnitude above the RISR velocity magnitude. We argue that, for one event, the velocity overestimation occurs owing to echo detection from a laterally refracted RKN beam while, generally, the effect should be fairly wide-spread in SuperDARN data because of microstructures with enhanced electron density in the scattering volume that might have either weak irregularities or increased local electric fields. We estimate that the correction of RKN velocity data by considering the effect of the index of refraction improves RKN-RISR velocity agreement but only for 63% of points. This implies that care should be exersised when attempting to correct raw SuperDARN velocity data by the index of refraction.

We present the first simulations of magnetospheric sawtooth oscillations under steady solar wind conditions that are driven internally by heavy ion outflow from a physics-based model. The simulations presented use the multifluid Lyon-Fedder-Mobarry magnetohydrodynamics model two-way coupled to the ionosphere/polar wind model (IPWM). Depending on the type of wave-particle interactions utilized within IPWM, the coupled simulations exhibit either sawtooth oscillations or steady magnetospheric convection. Contrasting the simulations that do and do not develop sawtooth oscillations yields insights into the relationship between outflow and sawtooth oscillations. The total outflow rate is not an adequate predictor of the convection mode that will emerge. The simulations that develop sawtooth oscillations are characterized by intense outflow concentrated in the midnight auroral region. This outflow distribution mass loads the tail reconnection region without excessively mass loading the dayside reconnection region and leads to an imbalance between the dayside and nightside reconnection rates.

Thermal ion retarding potential analyzers (RPAs) are used to measure in situ auroral ionospheric plasma parameters. This article analyzes data from a low-resource RPA in order to quantify the capability of the sensor. The RPA collects a sigmoidal current-voltage (I-V) curve, which depends on a non-linear combination of Maxwellian plasma parameters, so a forward-modeling procedure is used to match the best choice plasma parameters for each I-V curve. First, the procedure is used, given constraining information about the flow moment, to find scalar plasma parameters-ion temperature, ion density, and spacecraft sheath potential-for a single I-V curve interpreted in the context of a Maxwellian plasma distribution. Second, two azimuthally separated I-V curves from a single sensor on the spinning spacecraft are matched, given constraining information on density and sheath potential, to determine the bulk plasma flow components. These flows are compared to a high-fidelity, high-resource flow diagnostic. In both cases, the procedure's sensitivity to variations in constraining diagnostics is tested to ensure that the matching procedure is robust. Finally, a standalone analysis is shown, providing plasma scalar and flow parameters using known payload velocity and International Reference Ionosphere density as input information. The results show that the sensor can determine scalar plasma measurements as designed, as well as determine plasma DC flows to within hundreds of m/s error compared to a high-fidelity metric, thus showing their capability to replace higher-resource methods for determining DC plasma flows when coarse-resolution measurements at in situ spatial scales are suitable.