Our studies report the first observation of L‐value and energy sorted correlation of differential fluxes of 0.1–50 keV O+, He+, and H+ ions with different geophysical parameters for 29 Coronal Mass ...Ejected (CME) and 40 Corotating Interaction Region (CIR)‐driven geomagnetic storms during the entire Van Allen Probes era. For both solar wind drivers, ions with ≥1 keV energies show more variability in response to the solar wind changes, while the lower energy (<1 keV) ions are relatively stable. During the in‐storm interval, O+ ions show maximum flux enhancement and become further prominent during CME storms. O+ ion (≥10 keV) fluxes show good correlation with − VswBz, and Sym‐H index during CME‐driven storms in the L ∼2.5–5.5. Apart from this, the average duration of persistence (〈Δt〉) for enhanced fluxes is higher for CIR‐driven storms with 〈Δt〉O+ ${\langle {\Delta}t\rangle }_{{O}^{+}}$>〈Δt〉He+ ${\langle {\Delta}t\rangle }_{H{e}^{+}}$>〈Δt〉H+ ${\langle {\Delta}t\rangle }_{{H}^{+}}$ at E ≤ 50 keV in the L ∼2.5–5.5. Moreover, the observed value of 〈Δt〉i (where i is O+, H+ or He+) increases with the increasing L. We discuss the plausible mechanisms to provide a comprehensive overview of L‐values and energy sorted O+, He+ and H+ ion dynamics for two different categories of solar wind drivers.
Plain Language Summary
O+, He+, and H+ ions having energies ranging from ∼10 eV to 50 keV contribute to a majority of the ring current density that provides significant information about the important processes in the inner magnetosphere. In this study, we acquire high‐resolution data over the entire Van Allen Probes era to understand storm time dynamics of ion fluxes for the two different categories of solar wind drivers. We find a characteristic difference upon correlating the ion flux enhancement during the storm main phase with the solar wind parameters and strength of the magnetic storm at different L‐values and energies for both the category of solar wind drivers. Not all the energies and L‐values respond in a similar manner. Moreover, O+, He+, and H+ do not appear at the spacecraft location for the same duration of time. The time duration for which the ion fluxes remain at high is more for Corotating Interaction Region (CIR)‐driven storms than Coronal Mass Ejected (CME) ones. Our studies give a comprehensive overview of spatio‐temporal characteristics of the inner magnetospheric O+, He+, and H+ ions at different energies using a long‐term data set for CME and CIR‐driven geomagnetic storms.
Key Points
Coronal Mass Ejection (CME) storms produce more enhancements down to the lower L‐values for O+, He+, and H+ ions at ≤50 keV energies
For L = 2–5.5, ≥1 keV O+, He+, and H+ ion fluxes show highest correlation with −Sym‐H during CME storms
During CIR storms, O+, He+, and H+ ion fluxes remain at high for a longer period of time than during CME storms
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We examined rapid variations in the electron zebra stripe patterns, specifically at L = 1.5, over a three‐month duration, using twin Van Allen Probes within Earth's inner magnetosphere. During ...geomagnetically quiet intervals, these stripes exhibit a peak‐to‐valley ratio (Δj) ∼1.25 in detrended electron fluxes. However, during geomagnetic storms, they became highly prominent, with Δj > 2.5. The correlation between Δj and net field‐aligned currents (FACs) is observed to be high (0.70). Global magnetohydrodynamic (MHD) simulation results indicate that the westward electric field at midnight at low latitudes in the deep inner magnetosphere correlates well with net FACs. An increase in net FACs could amplify the dawn‐to‐dusk electric field in the deep inner magnetosphere, thereby causing the inward transport of electrons. Given that FACs are linked to the interaction between solar wind and the magnetosphere, our findings emphasize the importance of solar wind‐magnetosphere coupling in the deeper regions of the inner magnetosphere.
Plain Language Summary
The intensity of hundreds of keV electron fluxes displays a distinctive pattern in the energy versus L‐value spectrogram, characterized by periodic valleys and peaks, commonly referred to as zebra stripes. These patterns have been observed in the magnetospheres of multiple planets, including Earth, Jupiter, and Saturn. Our study reveals that during geomagnetically quiet intervals, Earth's inner magnetospheric zebra stripes exhibit well‐defined banded features. However, these bands become highly pronounced during geomagnetic storms. The peak‐to‐valley ratio (Δj) of detrended electron fluxes shows a correlation with net field‐aligned currents (FACs), and these FACs, in turn, align with the westward component of the electric field at midnight. Consequently, FACs play a significant role in controlling electron flux dynamics deep within the inner magnetosphere. This research illuminates the solar wind‐magnetosphere‐ionosphere couplings.
Key Points
Electron zebra stripes are a persistent feature in Earth's inner magnetosphere, although they become intensified during geomagnetic storms
Peak‐valley ratio (Δj) in detrended electron flux within the zebra stripes enhances by ≥1 factor at L = 1.5 during three geomagnetic storms
Δj is well correlated with the net field‐aligned current (FAC) in polar region, suggesting the dominant role of convection driven by FAC
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Relativistic electron flux responses in the inner magnetosphere are investigated for 28 magnetic storms driven by corotating interaction region (CIR) and 27 magnetic storms driven by coronal mass ...ejection (CME), using data from the Relativistic Electron‐Proton Telescope instrument on board Van Allen Probes from October 2012 to May 2017. In this present study we analyze the role of CIRs and CMEs in electron dynamics by sorting the electron fluxes in terms of averaged solar wind parameters, L‐values, and energies. The major outcomes from our study are the following: (i) At L = 3 and E = 3.4 MeV, for >70% cases the electron flux remains stable, while at L = 5, for ~82% cases it changes with the geomagnetic conditions. (ii) At L = 5, ~53% of the CIR storms and 30% of the CME storms show electron flux increase. (iii) At a given L‐value, the tendency for the electron flux variation diminishes with the increasing energies for both categories of storms. (iv) In case of CIR‐driven storms, the electron flux changes are associated with changes in Vsw and Sym‐H. (v) At L ~ 3, CME storms show increased electron flux, while at L ~ 5, CIR storms are responsible for the electron flux enhancements. (vi) During CME‐ and CIR‐driven storms, distinct electron flux variations are observed at L = 3 and L = 5.
Key Points
At L = 5, 53% of the CIR storms and 30% of the CME storms show electron flux increase
Relativistic electron flux variations at L = 5 is largely independent of geomagnetic storm strength but strongly depends upon averaged Vsw and IMF Bz
At L = 3, >71% geomagnetic storms show no remarkable electron flux variations, irrespective of the storm driver
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We report a rare regime of Earth's magnetosphere interaction with sub‐Alfvénic solar wind in which the windsock‐like magnetosphere transforms into one with Alfvén wings. In the magnetic cloud of a ...Coronal Mass Ejection (CME) on 24 April 2023, NASA's Magnetospheric Multiscale mission distinguishes the following features: (a) unshocked and accelerated low‐beta CME plasma coming directly against Earth's dayside magnetosphere; (b) dynamical wing filaments representing new channels of magnetic connection between the magnetosphere and foot points of the Sun's erupted flux rope; (c) cold CME ions observed with energized counter‐streaming electrons, evidence of CME plasma captured due to by reconnection between magnetic‐cloud and Alfvén‐wing field lines. The reported measurements advance our knowledge of CME interaction with planetary magnetospheres, and open new opportunities to understand how sub‐Alfvénic plasma flows impact astrophysical bodies such as Mercury, moons of Jupiter, and exoplanets close to their host stars.
Plain Language Summary
Like supersonically fast fighter jets creating sonic shocks in the air, planet Earth typically moves in the magnetized solar wind at super‐Alfvénic speeds and generates a bow shock. Here we report unprecedented observations of Earth's magnetosphere interacting with a sub‐Alfvénic solar wind brought by an erupted magnetic flux rope from the Sun, called a coronal mass ejection (CME). The terrestrial bow shock disappears, leaving the magnetosphere exposed directly to the cold CME plasma and the strong magnetic field from the Sun's corona. Our results show that the magnetosphere transforms from its typical windsock‐like configuration to having wings that magnetically connect our planet to the Sun. The wings are highways for Earth's plasma to be lost to the Sun, and for the plasma from the foot points of the Sun's erupted flux rope to access Earth's ionosphere. Our work indicates highly dynamic generation and interaction of the wing filaments, shedding new light on how sub‐Alfvénic plasma wind may impact astrophysical bodies in our solar and other stellar systems.
Key Points
MMS observed a rare regime of magnetosphere interaction with unshocked low‐beta CME plasma
Wing filaments represent dynamical channels of magnetic connection between the magnetosphere and foot points of the Sun's erupted flux rope
Cold CME ions observed on closed field lines, likely generated by dual‐wing reconnection
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Solar wind particles and ionospheric O
+
ions influence the near-Earth plasma sheet and inner magnetospheric composition. We studied the behavior of H
+
, O
+
and He
+
ions (9–210 keV) for intense ...and moderate geomagnetic storms of solar cycle 23 and 24. An average energy density <
ε
> of ions over a given interval and flux enhancement is estimated using observations from satellites at different L values, namely STICS sensor on-board Geotail spacecraft and HOPE spectrometer on-board Radiation Belt Storm Probes. It provides a comprehensive understanding of the energy density variation of H
+
, O
+
and He
+
ions with the strength of IMF Bz, Psw, intensity of storms and
L
value. Statistically, we observed that (1) In the plasma sheet region, during main phase of the intense geomagnetic storm, <
ε
O+/H+
> and <
ε
He+/H+
> enhances, (2) <
ε
O+/H+
> is well correlated with Psw (CC = 0.86) and IMF Bz (CC = 0.85), (3) <
ε
O+/H+
> shows higher correlation (CC = 0.73) with Kp than <
ε
He+/H+
> (CC = 0.65), indicating a fairly good dependence on the strength of geomagnetic activity, (4) <
ε
O+/H+
> and <
ε
He+/H+
> dependence on
L
value indicates that O
+
/H
+
and He
+
/H
+
is more pronounced near
L
= 3. It is a cumulative extension of the previous studies on ion composition change which is in accordance with the existing picture of the plasma sheet and inner magnetosphere.
We present multi‐spacecraft observations of the proton fluxes spanning from 1.5 to 433 MeV for the largest solar proton event of solar cycle 24, i.e., September 7 and 10, 2017. In September 2017, ...M5.5 flare on September 4, X9.3 flare on September 6 and X8.2 flare on September 10 gave rise to solar proton event when observed by near‐Earth spacecrafts. On September 7 and September 10, 2017, a strong enhancement in the proton intensities was observed by Advanced Composition Explorer (ACE) and WIND at L1 and Van Allen Probes, GOES‐15 and POES‐19 in the Earth's inner magnetosphere. Below geosynchronous orbit, Van Allen Probes and POES‐19 show that no significant proton flux was observed with energies ≤25 MeV on September 4, while the fluxes peaked 3 to 7‐times during September 7 and by ∼25 times during the third proton flux event on September 10, 2017. Van Allen Probe‐A observation shows that the closest distance that solar proton fluxes could approach the Earth is L∼4.4 for 102.6 MeV energies on 10th September 2017, while lower energy protons i.e., 25 MeV are observed deep up to L∼3.4 on 11th September 2017. POES‐19 observations show that there is no particular magnetic local time (MLT) dependence of the solar proton flux and is symmetric everywhere at high and low latitudes. The measurements from multiple spacecrafts located in the different regions of the Earth's magnetosphere show that the increased level of solar proton flux population persisted for ∼2 days. Thus, we quantify the temporal flux variability in terms of L‐value, energy and MLT.
Plain Language Summary
During a solar energetic particle (SEP) event, energetic electrons and ions flood the heliosphere causing severe damage to satellites, radio communication and humans in space. The Earth's magnetic field controls the dynamics of these particles to near‐Earth space. One such unique event was observed in September 2017 for which the energy spectra and quantification of the proton fluxes spanning from 1.5 to 433 MeV using multi‐satellite observations is studied. This was the largest proton event of the solar cycle 24 with three M‐class and four X‐class flares were observed by near‐Earth spacecrafts. Proton fluxes were quantified at different locations like L1 point, geostationary orbit, inner magnetosphere, and low altitudes. The extent of flux enhancements, its access into the Earth's magnetosphere, MLT dependence and time to reach maximum fluxes are computed and compared before and after the SEPs arrived. We show that the multiple spacecraft observations are the key tool to quantify the temporal flux variability in terms of L‐value, energy and MLT.
Key Points
Peak proton fluxes with energies >20 MeV at L = 6.6 on 10th September were >2 order higher than the ones observed on September 7, 2017
Solar proton fluxes were observed as close as L∼3.4
Solar proton fluxes show no particular magnetic local time dependence
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The incidence of anemia rises with age. The consequences of anemia are many and serious, affecting not only individual's health, but also the development of societies and countries. Pandu Roga can be ...effectively compared with anemia on the ground of its similar signs and symptoms.
To evaluate the Panduhara and Rasayana effect of Punarnava Mandura in the management of Pandu Roga in old age (geriatric anemia).
The study was conducted in 50 clinically diagnosed patients of geriatric anemia. Patients were treated with Punarnava Mandura 2 tablets (250 mg each) twice in a day after lunch and dinner with Takra (butter milk) for 90 days. Among 50 registered patients, 40 patients had completed the treatment and 10 patients discontinued the treatment. Results were analyzed using Wilcoxon signed-rank test for subjective parameters and for assessment of objective parameters paired t-test was adopted.
At the end of study, drug has shown beneficial effect in patients of anemia by providing highly significant result in chief complaints, associated symptoms, Kshaya of Dhatu and Agni Bala, Deha Bala and Sattwa Bala. It has also improved quality-of-life (QOL) of the patients. Moderate and mild improvement was observed in 30 and 70% of the patients respectively.
Punarnava Mandura may work as Rasayana in geriatric anemia by providing highly significant results on clinical features of Pandu Roga, Dehabala, Agni Bala and Sattwa Bala and by improving QOL. of patients of geriatric anemia.
Zebra stripes are the characteristic structures having repeated hills and valleys in the electron flux intensities observed below L = 3. We delineate the fundamental properties and evolution of ...electron zebra stripes by modeling advection using time‐dependent electric fields provided by a global magnetohydrodynamics simulation. At the beginning of the simulation, the electrons were uniformly distributed in longitude. Some electrons moved inward due to enhanced westward electric field transients in the premidnight‐postdawn region. The inwardly displaced electrons were confined in a narrow longitudinal range and underwent grad‐B and curvature drifts. For any specific fixed position, the electrons periodically passed through the point with an energy dependent period, giving rise to the hills and valleys in the electron differential flux also known as zebra stripes. The valleys of the zebra stripes are composed of the electrons that underwent outward displacement, or no significant radial displacement. On the nightside, the duskside convection cell is skewed toward dawn in the equatorward of the auroral oval, and the westward electric field becomes dominant in the postdawn region, which results in the inward motion of the electrons. The spatial distribution of the westward electric field is consistent with observation. Zebra stripes are a mixture of the electrons that have and have not experienced inward transport due to solar wind‐inner magnetosphere coupling by way of the ionosphere.
Key Points
Zebra stripes commonly appear in energy versus L spectrograms of energetic electrons in the inner magnetosphere
We performed advection simulation of trapped electrons with electric field obtained by global magnetohydrodynamics (MHD) simulation
Zebra stripes are consequence of drift echoes triggered by locally enhanced westward electric field along with field‐aligned current (FAC)
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Using Relativistic Electron Proton Telescope measurements onboard Van Allen Probes, the evolution of electron pitch angle distributions (PADs) during the different phases of magnetic storms is ...studied. Electron fluxes are sorted in terms of storm phase,
L value, energy, and magnetic local time (MLT) sectors for 55 magnetic storms from October 2012 through May 2017. To understand the potential mechanisms for the evolution of electron PADs, we fit PADs to a sinusoidal function
J0sinn(αeq), where
αeq is the equatorial pitch angle and n is a real number. The major inferences from our study are (i) at L
∼5, the prestorm electron PADs are nearly isotropic (n
∼0), which evolves differently in different MLT sectors during the main phase subsequently recovering back to nearly isotropic distribution type during the storm recovery phase; (ii) for
E
≤ 3.4 MeV, the main phase electron PADs become more pancake like on the dayside with high n values (>3), while it becomes more flattop to butterfly like on the nightside, (iii) at L = 5, magnetic field strength during the storm main phase enhances during the daytime and decreases during the nighttime. (iv) Conversely, at L
∼3, the electron PADs neither respond significantly to the different phase of the magnetic storm nor reflect any MLT dependence. (v) Main phase, electron fluxes with
E <4.2 MeV shows a persistent 90° maximum PAD with n ranging between 0 and 2, while for
E
≥ 4.2 MeV the distribution appears flattop and butterfly like. Our study shows that the relativistic electron PADs depend upon the geomagnetic storm phase and possible underlying mechanisms are discussed in this paper.
Key Points
Storm time electron pitch angle distributions (PADs) at L = 5 peak on the dayside, while it turns butterfly like on the nightside
At L = 3, PADs of electrons do not change significantly between prestorm and at‐storm intervals
Magnetic field during at storm interval (
Bat) decreases on the nightside, while increasing on the dayside
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The moderate and intense geomagnetic storms are identified for the first 77 months of solar cycles 23 and 24. The solar sources responsible for the moderate geomagnetic storms are indentified during ...the same epoch for both the cycles. Solar cycle 24 has shown nearly 80% reduction in the occurrence of intense storms whereas it is only 40% in case of moderate storms when compared to previous cycle. The solar and interplanetary characteristics of the moderate storms driven by coronal mass ejection (CME) are compared for solar cycles 23 and 24 in order to see reduction in geoeffectiveness has anything to do with the occurrence of moderate storm. Though there is reduction in the occurrence of moderate storms, the Dst distribution does not show much difference. Similarly, the solar source parameters like CME speed, mass, and width did not show any significant variation in the average values as well as the distribution. The correlation between VBz and Dst is determined, and it is found to be moderate with value of 0.68 for cycle 23 and 0.61 for cycle 24. The magnetospheric energy flux parameter epsilon (epsilon) is estimated during the main phase of all moderate storms during solar cycles 23 and 24. The energy transfer decreased in solar cycle 24 when compared to cycle 23. These results are significantly different when all geomagnetic storms are taken into consideration for both the solar cycles.
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