Ring Current-atmosphere Interactions Model Research Articles

RAM‐SCB Runs on Request at CCMC

AbstractThe Ring current–Atmosphere interactions Model (RAM) with Self‐Consistent magnetic (B) field (SCB) combines a large‐scale kinetic model of ring current plasma with a three‐dimensional (3‐D) force‐balanced model of the terrestrial magnetic field. RAM‐SCB simulates the evolution of major ion species (H+, O+, and He+ by default) and electrons as a function of azimuth, radial distance, energy, and pitch angle. Simulation outputs include the Dst index, and pressure and differential flux of the modeled species, thus providing benefit as a science code and to inform surface charging hazard within the model domain. Version 2.2 of this open‐source simulation code has now—as of 8 August 2023—been made available for Runs‐On‐Request via the Community Coordinated Modeling Center.

The RAM-SCB model and its applications to advance space weather forecasting

Energetic particle fluxes that are part of the Earth’s ring current and radiation belts can intensify significantly during space weather events like geomagnetic storms and could cause severe damage to satellite-based technologies. Understanding the physical processes that control their dynamics and improving our capability for their prediction is thus extremely important. In the context of space weather applications and user needs, this paper provides a brief description of our kinetic ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB) and its further extension to implement a self-consistent electric (E) field. Specific examples that demonstrate RAM-SCB capabilities and limitations to reproduce the near-Earth space weather environment are given. The current status of RAM-SCB is assessed and plans for its further improvement are discussed.

Simulating the effects of warm O[formula omitted] ions on the growth of electromagnetic ion cyclotron (EMIC) waves

Electromagnetic ion cyclotron (EMIC) waves are believed to play a crucial role in the dynamics of the Earth’s magnetosphere. It has been widely accepted that plasma compositions can influence the growth rate of EMIC waves in the inner magnetosphere, but how warm O+ ions change the wave growth rate is not well known. In this study, we investigate the impact of ring current O+ concentration on the EMIC growth rate during a specific storm when the O+ ion flux significantly increases. We calculate the growth rate of EMIC waves by using physics-based ion distributions output from the Ring current–Atmosphere interactions Model with Self-Consistent magnetic (B) and Electric (E) fields (RAM-SCBE) model. The percentage of warm O+ is parametrically varied to examine how the maximum EMIC growth rate changes over time and how the global distribution of the maximum EMIC growth rate is affected. We found that the maximum growth rate of H-band appears in the dusk-to-midnight sector near the plasmapause, while O-band is excited at a slightly outer region. The maximum growth rate of He-band is closely related to the cold plasma density. With the increase of warm O+ density, the maximum growth rate of H-band and He-band EMIC wave is reduced, while that of O-band EMIC wave is increased, and the region with this wave excitation is widened. Such variation in the maximum EMIC growth rate implies a potential impact on the associated wave–particle interactions and change of the decay rate in the ring current.

Contribution of Electron Pressure to Ring Current and Ground Magnetic Depression Using RAM‐SCB Simulations and Arase Observations During 7–8 November 2017 Magnetic Storm

AbstractUnderstanding the physical processes that control the dynamics of energetic particles in the inner magnetosphere is important for both space‐borne and ground‐based assets essential to the modern society. The storm time distribution of ring current particles in the inner magnetosphere depends strongly on their transport in the evolving electric and magnetic fields along with particle acceleration and loss. In this study, we investigated the ring current particle variations using observations and simulations. We compared the ion (H+, He+, and O+) and electron flux and plasma pressure variations from Arase observations with the self‐consistent inner magnetosphere model: Ring current Atmosphere interactions Model with Self Consistent magnetic field (RAM‐SCB) during the 7–8 November 2017 geomagnetic storm. We investigated the contribution of the different species (ions and electrons) to the magnetic field deformation observed at ground magnetic stations (09°–45° MLat) using RAM‐SCB simulations. The results show that the ions are the major contributor with ∼88% and electrons contribute ∼12% to the total ring current pressure. It is also found that the electron contribution is non‐negligible (∼18%) to the ring current in dawn‐side during the main phase of the storm. Thus, the electron contribution to the storm time ring current is important and should not be neglected.

Global Simulation of Electron Cyclotron Harmonic Wave Instability in a Storm‐Time Magnetosphere

AbstractElectron cyclotron harmonic (ECH) waves are electrostatic emissions between the ECHs and play a dominant role for precipitating energetic electrons in the magnetotail. Statistically, the ECH wave intensity is stronger at nightside and dawnside than at dayside and duskside. In this study, we, for the first time, simulate the global ECH wave evolution during a geomagnetic storm event using Ring current Atmosphere interactions Model with Self‐Consistent Magnetic field (RAM‐SCB) combined with a linear growth rate solver. We find that the simulation results are generally consistent with the statistical and real‐time observations. The ECH wave instability is much stronger at nightside and dawnside, compared to the instability at dayside and duskside. Before a geomagnetic storm (quiet time), the unstable regions of the ECH waves lie beyond with a weak instability level. During the main phase of a geomagnetic storm, the unstable regions can extend to a lower altitude ( ) with a strong instability level. During the recovery phase, the unstable regions return to . We also find that the inner boundary of unstable ECH wave regions is coincident with the plasmapause location during the whole geomagnetic storm event.

Integration of RAM-SCB into the Space Weather Modeling Framework

Numerical simulations of the ring current are a challenging endeavor. They require a large set of inputs, including electric and magnetic fields and plasma sheet fluxes. Because the ring current broadly affects the magnetosphere-ionosphere system, the input set is dependent on the ring current region itself. This makes obtaining a set of inputs that are self-consistent with the ring current difficult. To overcome this challenge, researchers have begun coupling ring current models to global models of the magnetosphere-ionosphere system. This paper describes the coupling between the Ring current Atmosphere interaction Model with Self-Consistent Magnetic field (RAM-SCB) to the models within the Space Weather Modeling Framework. Full details on both previously introduced and new coupling mechanisms are defined. The impact of self-consistently including the ring current on the magnetosphere-ionosphere system is illustrated via a set of example simulations.

RAM-SCB simulations of electron transport and plasma wave scattering during the October 2012 "double-dip" storm.

Mechanisms for electron injection, trapping, and loss in the near‐Earth space environment are investigated during the October 2012 “double‐dip” storm using our ring current‐atmosphere interactions model with self‐consistent magnetic field (RAM‐SCB). Pitch angle and energy scattering are included for the first time in RAM‐SCB using L and magnetic local time (MLT)‐dependent event‐specific chorus wave models inferred from NOAA Polar‐orbiting Operational Environmental Satellites (POES) and Van Allen Probes Electric and Magnetic Field Instrument Suite and Integrated Science observations. The dynamics of the source (approximately tens of keV) and seed (approximately hundreds of keV) populations of the radiation belts simulated with RAM‐SCB is compared with Van Allen Probes Magnetic Electron Ion Spectrometer observations in the morning sector and with measurements from NOAA 15 satellite in the predawn and afternoon MLT sectors. We find that although the low‐energy (E< 100 keV) electron fluxes are in good agreement with observations, increasing significantly by magnetospheric convection during both SYM‐H dips while decreasing during the intermediate recovery phase, the injection of high‐energy electrons is underestimated by this mechanism throughout the storm. Local acceleration by chorus waves intensifies the electron fluxes at E≥50 keV considerably, and RAM‐SCB simulations overestimate the observed trapped fluxes by more than an order of magnitude; the precipitating fluxes simulated with RAM‐SCB are weaker, and their temporal and spatial evolutions agree well with POES/Medium Energy Proton and Electron Detectors data.

The two‐way relationship between ionospheric outflow and the ring current

AbstractIt is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first‐principles‐based numerical models to test the dependence of ionospheric outflow on ring current‐driven region 2 field‐aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptive Tree Solar wind Roe‐type Upwind Scheme, BATS‐R‐US), a polar wind model (Polar Wind Outflow Model), and a bounce‐averaged kinetic ring current model (ring current atmosphere interaction model with self‐consistent magnetic field, RAM‐SCB). Initially, each code is two‐way coupled to all others except for RAM‐SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS‐R‐US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the noncoupled results. The additional outflow further energizes the ring current, establishing an ionosphere‐magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere‐magnetosphere‐ring current system.

Validation study of the magnetically self‐consistent inner magnetosphere model RAM‐SCB

The validation of the magnetically self‐consistent inner magnetospheric model RAM‐SCB developed at Los Alamos National Laboratory is presented here. The model consists of two codes: a kinetic ring current–atmosphere interaction model (RAM) and a 3‐D equilibrium magnetic field code (SCB). The validation is conducted by simulating two magnetic storm events and then comparing the model results against a variety of satellite in situ observations, including the magnetic field from Cluster and Polar spacecraft, ion differential flux from the Cluster/CODIF (Composition and Distribution Function) analyzer, and the ground‐based SYM‐H index. The model prediction of the magnetic field is in good agreement with observations, which indicates the model's capability of representing well the inner magnetospheric field configuration. This provides confidence for the RAM‐SCB model to be utilized for field line and drift shell tracing, which are needed in radiation belt studies. While the SYM‐H index, which reflects the total ring current energy content, is generally reasonably reproduced by the model using the Weimer electric field model, the modeled ion differential flux clearly depends on the electric field strength, local time, and magnetic activity level. A self‐consistent electric field approach may be needed to improve the model performance in this regard.

Self‐consistent inner magnetosphere simulation driven by a global MHD model

We present results from a one‐way coupling between the kinetic Ring Current Atmosphere Interactions Model with Self‐Consistent B field (RAM‐SCB) and the Space Weather Modeling Framework (SWMF). RAM‐SCB obtains plasma distribution and magnetic field at model boundaries from the Block Adaptive Tree Solar Wind Roe Upwind Scheme (BATS‐R‐US) magnetohydrodynamics (MHD) model and convection potentials from the Ridley Ionosphere Model within SWMF. We simulate the large geomagnetic storm of 31 August 2005 (minimum SYM‐H of −116 nT). Comparing SWMF output with Los Alamos National Laboratory geostationary satellite data, we find SWMF plasma to be too cold and dense if assumed to consist only of protons; this problem is alleviated if heavier ions are considered. With SWMF inputs, we find that RAM‐SCB reproduces well storm time magnetosphere features: ring current morphology, dusk side peak, pitch angle anisotropy, and total energy. The RAM‐SCB ring current and Dst are stronger than the SWMF ones and reproduce observations much better. The calculated field‐aligned currents (FAC) compare reasonably well with 2 h averaged pictures from Iridium satellite data. As the ring current peak rotates duskward in the storm main phase, the region 2 FACs rotate toward noon, a feature also seen in observations. Finally, the RAM‐SCB magnetic field outperforms both the dipole and the BATS‐R‐US field at Cluster and Polar spacecraft locations. This study shows the importance of a kinetic self‐consistent approach and the sensitive dependence of the storm time inner magnetosphere on plasma sheet conditions and the cross polar cap potential. The study showcases the RAM‐SCB capability as an inner magnetosphere module coupled with a global MHD model.

Excitation of whistler mode chorus from global ring current simulations

We simulate ring current dynamics during the 22 April 2001 geomagnetic storm (Dstmin = −102 nT) using our global ring current–atmosphere interactions model (RAM) extended to relativistic energies and electrons. The model retains four dimensions by solving the bounce‐averaged kinetic equation as a function of radial distance in the equatorial plane, magnetic local time (MLT), energy, and pitch angle. RAM includes time‐dependent convective transport and radial diffusion, all major loss processes, and is coupled with a dynamic 2‐D plasmasphere model. The global electric fields, as well as the boundary conditions at geosynchronous orbit, are specified from the Rice Convection Model (RCM) driven by a plasma sheet source population that depends on interplanetary conditions. The 1–30 keV electron fluxes simulated with RAM during the main phase of the storm at 4 ≤ L ≤ 6.5 agree reasonably well with THEMIS statistical data for active times (AE* &gt; 300 nT). We calculate the pitch angle anisotropy of ring current electrons and the linear growth rate of whistler mode chorus in the equatorial plane at L ≤ 6.5 and for all MLT. Intense chorus waves are generated outside the plasmasphere (L &gt; 4) in the premidnight to dawn local time sector by ring current electrons with ∼5 keV resonant energy. The chorus intensification on the dayside is smaller, and it is caused by higher‐energy ∼10 keV electrons. We present first results of the path‐integrated amplification of chorus obtained with the HOTRAY code using RAM outputs at selected locations. Significant chorus amplification with wave gain G ≥ 200 dB is obtained near local midnight after the fresh injections of ring current electrons from the plasma sheet. The global distribution of enhanced chorus waves on the nightside shows good agreement with recent surveys of near‐equatorial plasma wave data from satellites.

Comparative Study of Subauroral Polarization Streams with DMSP Observation and RAM Simulation

AbstractSubauroral Polarization Streams (SAPS) are fast westward plasma flows, located mainly at dusk and premidnight subauroral region. They are one of the important magnetosphere‐ionosphere‐thermosphere coupling processes. This work has simulated one storm time SAPS event with the Ring current‐Atmosphere Interaction Model (RAM) developed by University of Michigan. The model results are compared with the DMSP observations. It shows: the model results can be comparable with the observations in general; the latitude of the modeled SAPS peak velocity differed greatly from the observations; the observed SAPS velocities have two peaks around 18:00 UT and 20:00 UT, while the modeled have only one peak around 18:00 UT, which is due to the model's inability in the modeling of the substorm process.

Ring current development during high speed streams

Episodes of southward ( B z < 0 ) interplanetary magnetic field (IMF) which lead to disturbed geomagnetic conditions are associated either with coronal mass ejections (CMEs) and possess long and continuous negative IMF B z excursions, or with high speed solar wind streams (HSS) whose geoeffectiveness is due to IMF B z profiles fluctuating about zero with various amplitudes and duration. We simulate ring current evolution during a HSS-driven storm that occurred during 24–26 October 2002 and compare its dynamics with a CME-driven storm of similar strength during 22–23 April 2001. We use our kinetic ring current–atmosphere interactions model (RAM), and investigate the mechanisms responsible for trapping particles and for causing their loss. Ring current evolution depends on the interplay of time-dependent inflow of plasma from the magnetotail, particle acceleration and loss (mainly due to charge exchange) along adiabatic drift paths, and outflow of plasma from the dayside magnetopause; all of these processes are incorporated in our model. We compare results from simulations using a newly developed, Cluster data based, University of New Hampshire inner magnetospheric electric field (UNH–IMEF) convection model with simulations using a Volland–Stern (V–S) type convection model. We find that, first, periods of increased magnetospheric convection coinciding with enhancements of plasma sheet density are needed for strong ring current buildup. Second, during the HSS-driven storm the convection potential from UNH–IMEF model is highly variable and causes sporadic shallow injections resulting in a weak ring current. The long period of enhanced convection during the CME-driven storm causes a continuous ion injection penetrating to lower L shells and stronger ring current buildup. V–S model predicts larger ring current injection during both storms. Third, the RAM driven by either convection model underestimates the total ring current energy during the recovery phase of the HSS storm, thus indicating that additional injections from substorm-induced electric fields and/or radial diffusion are needed to better reproduce its several-day long geomagnetic activity.

Analyzing electric field morphology through data‐model comparisons of the Geospace Environment Modeling Inner Magnetosphere/Storm Assessment Challenge events

The storm time inner magnetospheric electric field morphology and dynamics are assessed by comparing numerical modeling results of the plasmasphere and ring current with many in situ and remote sensing data sets. Two magnetic storms are analyzed, 22 April 2001 and 21–23 October 2001, which are the events selected for the Geospace Environment Modeling (GEM) Inner Magnetosphere/Storms (IM/S) Assessment Challenge (IMSAC). The IMSAC seeks to quantify the accuracy of inner magnetospheric models as well as synthesize our understanding of this region. For each storm, the ring current‐atmosphere interaction model (RAM) and the dynamic global core plasma model (DGCPM) were run together with various settings for the large‐scale convection electric field and the nightside ionospheric conductance, while keeping all other simulation settings the same. DGCPM plasmaspheric parameters were compared with IMAGE‐EUV plasmapause extractions and LANL‐MPA plume locations and velocities. RAM parameters were compared with Dst*, LANL‐MPA fluxes and moments, IMAGE‐MENA images, and IMAGE‐HENA images. Both qualitative and quantitative comparisons were made to determine the electric field morphology that allows the model results to best fit the plasma data at various times during these events. The simulations with self‐consistent electric fields were, in general, better than those with prescribed field choices. This indicates that the time‐dependent modulation of the inner magnetospheric electric fields by the nightside ionosphere is quite significant for accurate determination of these fields (and their effects). It was determined that a shielded Volland‐Stern field description driven by the 3‐hour Kp index yields accurate results much of the time but can be quite inconsistent. The modified McIlwain field description clearly lagged in overall accuracy compared to the other fields, but matched some data sets (like Dst*) quite well. The rankings between the simulations varied depending on the storm and the individual data sets, indicating that each field description did well for some place, time, and energy range during the events, as well as doing less well in other places, times, and energies. Several unresolved issues regarding the storm time inner magnetospheric electric field are discussed.

Evolution of the proton ring current energy distribution during 21–25 April 2001 storm

Three ring current models are used to follow the evolution of the proton ring current during the 2001‐04‐21–25 storm: The ring current model combined with tracing particles numerically in the drift approximation by Ganushkina et al. (2005), the empirical model of proton fluxes in the inner magnetosphere developed by Milillo et al. (2003), and the kinetic ring current‐atmosphere interaction model (RAM) by Liemohn et al. (2001). The paper focuses on the effects of the electric and magnetic field models and initial particle distributions on the final energy distribution. We examine a variety of large‐scale magnetic field and convection electric field models as well as substorm‐associated, smaller‐scale, and time‐varying electric fields. We find that (1) using more realistic magnetic field models leads to reduction of the ring current energy content by ∼30%; (2) details of the global convection field have little influence on the overall ring current evolution; (3) smaller‐scale impulsive electric field have profound effects on the ring current evolution, particularly with regard to the acceleration of the higher‐energy particles; and (4) in the ring current models, the choice of the initial and boundary conditions have significant effects on the modeled ring current intensity and energy spectrum.

Storm‐time plasma signatures observed by IMAGE/MENA and comparison with a global physics‐based model

We present energetic neutral atom (ENA) fluxes measured by the medium energy neutral atom (MENA) imager onboard the IMAGE satellite for the geomagnetic storm of 21 October 2001 at energies of 6 and 12 keV. The fluxes indicate strong low altitude emissions close to the Earth and a nightside peak close to local midnight. The fluxes are compared with theoretical ENA fluxes calculated using the ring current‐atmosphere interaction model (RAM). We find good quantitative agreement between MENA data and RAM results, both of which indicate a peak in ENA emissions on the nightside, close to local midnight which varies in radial location between ∼2 and ∼5 Re during the period of study. We demonstrate the validity of comparing RAM results with MENA data and pave the way for further study of plasma sheet entry to the inner magnetosphere during storm‐times.

Reconciling prediction algorithms forDst

The Burton et al. equation and the Ring Current Atmosphere Interaction Model (RAM) code give about equally good fits to Dst profiles of strong magnetic storms, yet they are driven by different functions of the interplanetary electric field, one rising linearly and the other eventually saturating. We show that by reformulating the Burton et al. equation such that a quadratic form of the driving term replaces the original linear form, the new prediction algorithm driven by the saturation form of the driving electric field produces about equally good fits to Dst as the original Burton et al. equation and the RAM code. The form of the quadratic driving term is constructed by specializing a general form given by dimensional analysis.

New Insights on Geomagnetic Storms from Model Simulations Using Multi-Spacecraft Data

The forecast of the terrestrial ring current as a major contributor to the stormtime Dst index and a predictor of geomagnetic storms is of central interest to ‘space weather’ programs. We thus discuss the dynamical coupling of the solar wind to the Earth's magnetosphere during several geomagnetic storms using our ring current-atmosphere interactions model and coordinated space-borne data sets. Our model calculates the temporal and spatial evolution of H+, O+, and He+ ion distribution functions considering time-dependent inflow from the magnetotail, adiabatic drifts, and outflow from the dayside magnetopause. Losses due to charge exchange, Coulomb collisions, and scattering by EMIC waves are included as well. As initial and boundary conditions we use complementary data sets from spacecraft located at key regions in the inner magnetosphere, Polar and the geosynchronous LANL satellites. We present recent model simulations of the stormtime ring current energization due to the enhanced large-scale convection electric field, which show the transition from an asymmetric to a symmetric ring current during the storm and challenge the standard theories of (a) substorm-driven, and (b) symmetric ring current. Near minimum Dst there is a factor of ∼ 10 variation in the intensity of the dominant ring current ion specie with magnetic local time, its energy density reaching maximum in the premidnight to postmidnight region. We find that the O+ content of the ring current increases after interplanetary shocks and reaches largest values near Dst minimum; ∼ 60% of the total ring current energy was carried by O+ during the main phase of the 15 July 2000 storm. The effects of magnetospheric convection and losses due to collisions and wave-particle interactions on the global ring current energy balance are calculated during different storm phases and intercompared.

Ring current dynamics during the 13-18 July 2000 storm period

We study the development of the terrestrial ring current during the time interval of 13–18 July, 2000, which consisted of two small to moderate geomagnetic storms followed by a great storm with indices Dst=−300 nT and Kp=9. This period of intense geomagnetic activity was caused by three interplanetary coronal mass ejecta (ICME) each driving interplanetary shocks, the last shock being very strong and reaching Earth at ∼ 14 UT on 15 July. We note that (a) the sheath region behind the third shock was characterized by B z fluctuations of ∼35 nT peak-to-peak amplitude, and (b) the ICME contained a negative to positive B z variation extending for about 1 day, with a ∼ 6-hour long negative phase and a minimum B z of about −55 nT. Both of these interplanetary sources caused considerable geomagnetic activity (Kp=8 to 9) despite their disparity as interplanetary triggers. We used our global ring current-atmosphere interaction model with initial and boundary conditions inferred from measurements from the hot plasma instruments on the Polar spacecraft and the geosynchronous Los Alamos satellites, and simulated the time evolution of H+, O+, and He+ ring current ion distributions. We found that the O+ content of the ring current increased after each shock and reached maximum values of ∼ 60% near minimum Dst of the great storm. We calculated the growth rate of electromagnetic ion cyclotron waves considering for the first time wave excitation at frequencies below O+ gyrofrequency. We found that the wave gain of O+ band waves is greater and is located at larger L shells than that of the He+ band waves during this storm interval. Isotropic pitch angle distributions indicating strong plasma wave scattering were observed by the imaging proton sensor (IPS) on Polar at the locations of maximum predicted wave gain, in good agreement with model simulations.

Effects of a high‐density plasma sheet on ring current development during the November 2–6, 1993, magnetic storm

The growth and recovery of the November 2–6, 1993 magnetic storm was simulated using a drift‐loss ring current model that was driven by dynamic fluxes at geosynchronous orbit as an outer boundary condition. During the storm main phase, a high‐density plasma sheet was observed by the Los Alamos National Laboratory geosynchronous satellites to move into and flow around the inner magnetosphere over a period of ∼12 hours [Borovsky et al., 1997; this issue] during the storm main phase. Densities at the leading edge of this structure reached 3 cm−3 as compared with more typical values &lt;1 cm−3. The factor of 3 change in the plasma sheet density from quiet to active times produced a factor of 3 enhancement in the strength of the simulated ring current. In addition, a short‐timescale recovery in the Dst index at 1600 UT on November 4 was driven by changes in the outer boundary condition and appeared even in the absence of collisional losses. An overshoot in the minimum Dst* occurred in the simulated ring current compared with observed values at ∼0200 UT on November 4 and is taken as evidence of a loss process not included in the ring current‐atmosphere interaction model (RAM). The storm onset was associated with a compression of the entire dayside magnetopause to within geostationary orbit starting at 2307 UT and continuing for a half hour. It is suggested that a possible additional loss may have resulted as ions drifted to the compressed dayside magnetopause. In fact such losses were found in another simulation of the inner magnetosphere for the same storm by Freeman et al. [1996]. The energy supplied to the inner magnetosphere, relative to the total energy input during this magnetic storm, was examined by comparing two widely used energy input functions, the ε parameter [Akasofu, 1981] and the F parameter [Burton et al., 1975] against energy input to the ring current model based on geosynchronous plasma observations at the outer boundary. It is found that the ε parameter [Akasofu, 1981] overestimates the ring current energy input compared to the drift‐loss model by almost an order of magnitude during the main phase. However, the integrated energy input from ε, over the 4 day interval of the storm, is in very good agreement with the total energy input inferred from observations. On the other hand, F more closely approximates the magnitude of the ring current energy input alone as calculated in the drift‐loss model. An energy budget is constructed for the storm that shows energy inputs from the solar wind and energy dissipation due to ring current buildup and decay, auroral electron precipitation, Joule heating, ion precipitation, and energy storage in the magnetotail in reasonable balance. The ring current energy input accounts for only 15% of the total dissipated energy in this storm interval. A more complete energy budget that extends to November 11, 1993, was compiled by Knipp et al. [this issue].