Big data technology provides a detailed development of English language teaching, which is targeted through the assessment of cognitive level. In this paper, ConvSLSTM is used to describe the problem ...of learners’ knowledge level and build a cognitive framework. With the support of the framework, “recall rate” was introduced to quantify the English vocabulary test results, PSTM ability was adopted to reflect the acquisition of syntactic variants, and attention control was borrowed to evaluate pronunciation characteristics. Based on the initial quantification mentioned above, a hierarchical-level calculation was accomplished by combining fuzzy logic. Meanwhile, based on the estimation of different sides, a rule space model was created, and some corrections were made to achieve the cognitive diagnosis of the group level. In terms of the syntactic developmental trajectory of the girl learners, the maximum value of the range of syntactic variation of the subjects appeared in the middle and late stages. During the early stages of development, the variation range is between 10-35, and the bandwidth is 25, with very little variation. However, in the middle stage of development, it basically starts to oscillate significantly between 10-85, at which time the bandwidth increases to 75. Big data technology has created a comprehensive measurement framework for learners’ English proficiency.
During the Earth's magnetic reversal, the dipole component of the magnetic field weakens, and the non‐dipole component becomes dominant, resulting in a far more complex magnetospheric topology than ...that of a dipole. In this study, we used a particle tracing technique to investigate the motion of ions within an irregular magnetosphere during the Matuyama‐Brunhes magnetic polarity reversal. Compared to the scenario in which the geomagnetic field is dominated by a dipole component, earthward‐moving particles can be hardly “trapped” in the inner magnetosphere when the geomagnetic field experiences the polarity reversal, and particles can directly precipitate into the Earth's atmosphere on a global scale. It suggests that under an irregular magnetospheric configuration, the traditional trapped region of particles (e.g., radiation belt or ring current) no longer exists.
Plain Language Summary
During the Earth's paleomagnetic reversal, the strength of the Earth's magnetic field was approximately 10% of its current value, accompanied by a weakening of the dipole component and an enhancement of the non‐dipole component. Under the superposition of this non‐axisymmetric multipole magnetic field, the magnetospheric structures may undergo significant changes. How charged particles travel in such an irregular magnetosphere and how different their trajectories are compared to the well‐known textbook scenario are still unknown. In this study, by utilizing global MHD simulations and test‐particle tracing techniques, we trace the charged particle's trajectory within the magnetosphere during the Matuyama‐Brunhes magnetic polarity reversal. We found that under an irregular magnetosphere in the middle stage of the geomagnetic reversal, particles in the inner magnetosphere cannot be constantly trapped around the Earth. The traditional trapped region (e.g., radiation belt or ring current) no longer exists. Particles moving Earthward do not gain the same acceleration effect as those under the present‐day magnetic field topology, resulting in a globally distributed pattern of particle precipitation. These differences can affect the global energy deposition and particle distribution in near‐Earth space.
Key Points
We simulated charged particles' trajectories in the magnetosphere during the Matuyama‐Brunhes reversal
Particles cannot be “trapped” in an irregular magnetosphere
The irregular geomagnetic field results in global particle precipitation
In the ring current dynamics, various loss mechanisms contribute to the ring current decay, including losses to the upper atmosphere through particle precipitation. This study implements the field ...line curvature (FLC) scattering mechanism in a kinetic ring current model and investigates its role in precipitating ions into the ionosphere during the 17 March 2013 storm. Simulation results indicate that (1) the FLC scattering process exerts on energetic ions on the nightside where the magnetospheric configuration is more stretching. It is more effective on heavy ions (e.g., O+). These ion losses thereafter lead to a faster recovery of the ring current. (2) The FLC‐associated ion precipitation mainly occurs in the outer region (L > 5 for protons and L > 4.5 for oxygen ions) on the nightside. The O+ precipitation takes places in a wider region than protons although its intensity is much lower. Comparisons with POES observations suggest that more proton precipitation is needed in the inner region. This is probably caused by the less stretched configuration in the simulation that prevents more precipitation. It may also imply that other loss process is required in the model such as wave‐particle interactions. (3) The storm time precipitating proton flux of tens of keV due to the FLC scattering sometimes becomes comparable to that of electrons on the nightside, although electrons usually dominate the ionospheric energy deposition from the midnight eastward toward the dayside. (4) The FLC scattering process seems to be capable of explaining the formation of isotropic boundary in the ionosphere during the investigated event.
Key Points
Ion precipitation related to FLC scattering is confined outside L = 4–5 in the simulation; additional precipitation is needed in the inner zone
With associated FLC loss of major ions (H+, O+, He+), the ring current decays faster; FLC scattering can roughly explain the formation of IB
The precipitating energy flux of tens of keV protons due to FLC scattering is comparable to that of electrons at 18 < MLT < 03 and 56° < MLAT < 62°
Radial diffusion (RD) induced by ULF waves can contribute to particle acceleration and scattering. Past global simulations that incorporate RD often use dipole magnetic fields, which could not ...realistically reveal the role of RD. To better understand the effects of RD and identify whether a background magnetic field model matters in understanding the ring current dynamics in response to RD, we simulate a storm event with different magnetic configurations using a global kinetic ring current model. Results indicate that RD can effectively diffuse protons of hundreds of keV to inner regions (L ∼ 3.5), especially in recovery phase. Comparisons with in‐situ observations demonstrate that simulations with TS05 overall capture both the intensity and variations of proton fluxes with the aid of RD, whereas that with a dipole field significantly overestimates low‐L region fluxes. This study implies adopting realistic magnetic fields is important for correctly interpreting the role of RD.
Plain Language Summary
Ultra‐low‐frequency (ULF) waves in the magnetosphere can scatter particles and diffuse them radially, called radial diffusion, resulting in particle acceleration and scattering and even precipitation down to the upper atmosphere. The interaction between ULF waves and particles is highly dependent on the strength of the magnetic field. This study quantified the role of ULF wave radial diffusions in the ring current dynamics using a global ring current model under different magnetic field configurations. Results indicate that radial diffusion could efficiently migrate energetic particles inward to L ∼ 3.5, especially during storm recovery phase when the convection is weak. With a more realistic magnetic field configuration, distributions of energetic ring current particles agree much better with satellite observations than using a dipolar magnetic field. Adding the radial diffusion process in the simulation helps to accelerate particles and yield better data‐model comparisons.
Key Points
Radial diffusions are able to effectively diffuse energetic (80 ∼ 300 keV) ring current protons to L ∼ 3.5 especially during recovery phase
Simulations with a dipole field may overestimate the role of radial diffusion in low L regions, but underestimate in high L regions
Adopting a more realistic magnetic field model is necessary to correctly interpret the role of radial diffusion
Double‐peak subauroral ion drifts (DSAIDs), characterized by two high‐speed flow channels, is a newly identified flow structure in the subauroral ionosphere. He et al. (2016, ...https://doi.org/10.1002/2016GL069133) proposed that two region 2 field‐aligned currents (R2 FACs) might cause the DSAIDs. However, the underlying physical process that drives the double R2 FACs is unknown. This study reports a DSAIDs event and reveals its magnetospheric drivers. Defense Meteorological Satellite Program F18 satellite observed DSAIDs in the duskside subauroral region, which corresponded well to two low‐density troughs and two R2 FACs. The Van Allen Probe B demonstrated that intense substorm ion injections recurrently occurred prior to the formation of DSAIDs, suggesting a potential magnetospheric driver of DSAIDs. Simulation confirms that recurrent ion injections intensify the partial ring current and create double pressure peaks in the near‐Earth dusk‐to‐midnight region, leading two R2 FACs to flow into the ionosphere. The two R2 FACs are thus responsible for the DSAIDs formation. This study unveils the generation mechanism of DSAIDs and deepens the knowledge of the complex magnetosphere‐ionosphere system.
Key Points
Clear DSAIDs structures are observed in the ionosphere after multiple ion injections from the magnetotail
Modeling study confirms the causal relationship between recurrent injections and DSAIDs
Recurrent injections give rise to enhanced ring current with double pressure peaks, resulting in double R2 FACs and hence DSAIDs
Abstract
We investigate the seasonal variations of ion precipitation, utilizing observations from the Mars Atmosphere and Volatile Evolution mission spanning from 2014 January 4 to 2023 February 14. ...Our analysis reveals that a diminishing pattern characterizes the transition from Mars season
L
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0°–180° to Mars season
L
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180°–360°, manifesting as a reduction in precipitating ion fluxes. Additionally, we discern a significant influence of the crustal magnetic field on the seasonal variations in precipitating ion fluxes. Intriguingly, within regions where the crustal magnetic field exhibits a strong quasi-horizontal orientation, opposite seasonal trends become evident. The underlying physical mechanism driving these seasonal variations in ion precipitation is probably attributed to the mass loading effect that may decelerate the solar wind and influence the magnetic pileup. A detailed investigation is further demanded in the future.
Energetic particles precipitation, which transmits energy from the magnetosphere to the ionosphere, represents an important coupling process between two systems. In this study, we investigate the ...spatial distribution and temporal evolution of medium-energy (tens to hundreds of keV) energetic particle precipitation (both ions and electrons) with NOAA/POES observations. We found the following results: (1) During storm time, both energetic electron and proton precipitations exhibit dawn-dusk asymmetry in the equatorial plane, possibly caused by plasma waves that are excited and then interact with energetic electrons and protons at different local times. (2) The energetic proton precipitation appears to contain greater energy flux than electrons in storm time, which is contrary to the low-energy particle precipitation where the electrons carry the dominant precipitation energy. (3) The depth of the earthward inner boundary of precipitation in statistics is linearly correlated with geomagnetic activity levels, represented by the SYM-H index.
•Medium-energy (tens to hundreds of keV) energetic precipitation of electrons and protons both exhibits global asymmetry.•Energetic proton precipitation contains more energy flux than electrons, unlike the scenario in low-energy precipitation.•The Earthward extension of precipitation linearly correlates with the storm intensity measured by SYM-H index.
Heavy ions of ionospheric origin (O+) play an important role in altering global magnetospheric dynamics. While the heavy ions mainly originate from the dayside cusp and the nightside auroral region, ...the impact of these heavy ions on magnetospheric dynamics has not been differentiated. Controversy also remains on the role of heavy ions on tail stability and their energization mechanism in the magnetosphere. Two global MHD simulations are carried out to investigate the influence of heavy ion outflow from different source regions on reconnection rates, tail stability, and ring current energization. The local reconnection rate at the subsolar point and the total dayside reconnection rate are reduced after the outflow begins, but the decrease is more significant when the outflow comes out of the cusp region. Furthermore, the magnetotail is more disturbed when heavy ions flow out of the dayside cusp region as opposed to the nightside auroral zone. This implies that the role of O+ on tail stability is not definitively positive or negative; instead, the location of the source of heavy ions may be important in determining tail dynamics. Finally, the simulation reveals that the heavy ions originating from the dayside cusp region experience first adiabatic heating while traveling from the tail reconnection site toward the Earth and then further energization caused by flow braking near the outer boundary of the ring current.
Key Points
reconnection rates reduced more when outflow is originated from the cuspheavy ions energized through two steps after tail reconnectiontail stability depends on where the O+ comes out
During geomagnetic storms, magnetospheric wave activity drives the ion precipitation which can become an important source of energy flux into the ionosphere and strongly affect the dynamics of the ...magnetosphere‐ionosphere coupling. In this study, we investigate the role of Electro Magnetic Ion Cyclotron (EMIC) waves in causing ion precipitation into the ionosphere using simulations from the RAM‐SCBE model with and without EMIC waves included. The global distribution of H‐band and He‐band EMIC wave intensity in the model is based on three different EMIC wave models statistically derived from satellite measurements. Comparisons among the simulations and with observations suggest that the EMIC wave model based on recent Van Allen Probes observations is the best in reproducing the realistic ion precipitation into the ionosphere. Specifically, the maximum precipitating proton fluxes appear at L = 4–5 in the afternoon‐to‐night sector which is in good agreement with statistical results, and the temporal evolution of integrated proton energy fluxes at auroral latitudes is consistent with earlier studies of the stormtime precipitating proton energy fluxes and vary in close relation to the SYM‐H index. Besides, the simulations with this wave model can account for the enhanced precipitation of < 20 keV proton energy fluxes at regions closer to Earth (L < 5) as measured by NOAA/POES satellites, and reproduce reasonably well the intensity of <30 keV proton energy fluxes measured by DMSP satellites. It is suggested that the inclusion of H‐band EMIC waves improves the intensity of precipitation in the model leading to better agreement with the NOAA/POES data.
Key Points
Three different empirical Electro Magnetic Ion Cyclotron (EMIC) wave models are used in the simulation
A recent Van Allen Probes data‐based EMIC wave model produces precipitation patterns consistent with statistical and in‐situ observations
The inclusion of H‐band EMIC waves enhances precipitation intensity, leading to better agreement with data
A few to tens of keV electron precipitation that carries substantial energy source down to the upper atmosphere to create aurora is manifested as an important magnetosphere‐ionosphere coupling ...process. The precipitation is usually caused by scattering processes associated with plasma waves in the magnetosphere. The scattering process is often quantified by wave diffusion rates that indicate how fast an electron is scattered. Global models commonly use diffusion coefficients that are derived from statistical wave models. However, due to the statistical nature, many localized, transient features could be smeared out. In this study, we investigate electron precipitation using event‐specific diffusion coefficients that are obtained based on simultaneous in‐situ measured/inferred, rather than statistical, chorus wave dynamics. We find that the application of the event‐specific diffusion coefficients associated with a more dynamic and intense chorus wave model leads more electrons, particularly at several to tens of keV in the dawn‐to‐noon sector at L > 3, to precipitate than using statistical coefficients. The new simulation roughly captures both the intensity and variability of the precipitating flux as detected by the NOAA/POES satellites. Ionospheric electron density in the lower E region (100–120 km) observed by the mid‐latitude Millstone Hill radar is also much better reproduced, while the case using statistical diffusion coefficients underestimates the ionization rate. This study implies the importance of using event‐specific diffusion rates in simulating the diffuse electron precipitation and understanding the magnetosphere‐ionosphere coupling.
Plain Language Summary
Plasma waves in the Earth magnetosphere can knock energetic electrons down to the atmosphere, causing severe disturbances in the ionosphere and affecting satellite communication and navigation. Because of the practical importance, understanding the sources and subsequent impact on the upper atmosphere is one popular scientific subject in the magnetosphere‐ionosphere community. It is known that whistler‐mode chorus waves, right‐hand polarized electromagnetic waves propagating along magnetic field lines, could interact with electrons at a gyrofrequency similar to the wave frequency and scatter them down to the ionosphere. Global simulations of wave–particle interactions and subsequent electron precipitation often adopt statistical chorus wave model, which however is incapable of quantitatively explaining the transient or localized enhancements in the electron precipitation. Therefore this study incorporates wave dynamics that is simultaneously measured/inferred to simulate the wave‐particle diffusion process. It is found that the new simulation causes more precipitation in the dawn‐to‐noon sector and displays much better agreement with satellite and radar observations, such as enhanced ionization around 100–120 km above the surface on the dayside. The study thus not only captures the causal relationship from the magnetosphere to low atmosphere in a global context, but also improves the model performance with a promising solution.
Key Points
Diffuse electron precipitation due to chorus wave scattering is simulated with either statistical or event‐specific diffusion coefficients
Simulation results are compared with observations from NOAA/POES satellites and Millstone Hill radar
Event‐specific chorus wave‐induced pitch angle diffusion coefficients help produce more realistic results than statistical coefficients
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