scholarly journals The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

2015 ◽  
Vol 120 (9) ◽  
pp. 7493-7511 ◽  
Author(s):  
H. Zhao ◽  
X. Li ◽  
D. N. Baker ◽  
J. F. Fennell ◽  
J. B. Blake ◽  
...  
Keyword(s):  
Energy Density ◽  
Ring Current ◽  
Geomagnetic Storms ◽  
Energy Content ◽  
Ion Energy ◽  
Van Allen Probes

scholarly journals Ring current electron dynamics during geomagnetic storms based on the Van Allen Probes measurements

2016 ◽  
Vol 121 (4) ◽  
pp. 3333-3346 ◽  
Author(s):  
H. Zhao ◽  
X. Li ◽  
D. N. Baker ◽  
S. G. Claudepierre ◽  
J. F. Fennell ◽  
...  
Keyword(s):  
Ring Current ◽  
Geomagnetic Storms ◽  
Electron Dynamics ◽  
Van Allen Probes ◽  
Current Electron

Fine-scale taxonomic and temporal variability in the energy density of invertebrate prey of juvenile Chinook salmon Oncorhynchus tshawytscha

2020 ◽  
Vol 655 ◽  
pp. 185-198
Author(s):  
J Weil ◽  
WDP Duguid ◽  
F Juanes
Keyword(s):  
Energy Density ◽  
Chinook Salmon ◽  
Temporal Variability ◽  
Energy Content ◽  
Single Point ◽  
Single Species ◽  
Fine Scale ◽  
Temporal Differences ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Variation in the energy content of prey can drive the diet choice, growth and ultimate survival of consumers. In Pacific salmon species, obtaining sufficient energy for rapid growth during early marine residence is hypothesized to reduce the risk of size-selective mortality. In order to determine the energetic benefit of feeding choices for individuals, accurate estimates of energy density (ED) across prey groups are required. Frequently, a single species is assumed to be representative of a larger taxonomic group or related species. Further, single-point estimates are often assumed to be representative of a group across seasons, despite temporal variability. To test the validity of these practices, we sampled zooplankton prey of juvenile Chinook salmon to investigate fine-scale taxonomic and temporal differences in ED. Using a recently developed model to estimate the ED of organisms using percent ash-free dry weight, we compared energy content of several groups that are typically grouped together in growth studies. Decapod megalopae were more energy rich than zoeae and showed family-level variability in ED. Amphipods showed significant species-level variability in ED. Temporal differences were observed, but patterns were not consistent among groups. Bioenergetic model simulations showed that growth rate of juvenile Chinook salmon was almost identical when prey ED values were calculated on a fine scale or on a taxon-averaged coarse scale. However, single-species representative calculations of prey ED yielded highly variable output in growth depending on the representative species used. These results suggest that the latter approach may yield significantly biased results.

scholarly journals Decay of the Dst field of geomagnetic disturbance after substorm onset and its implication to storm-substorm relation

1996 ◽  
Vol 14 (6) ◽  
pp. 608-618 ◽  
Author(s):  
T. Iyemori ◽  
D. R. K. Rao
Keyword(s):  
Ring Current ◽  
Geomagnetic Storms ◽  
Sharp Decrease ◽  
Geomagnetic Disturbance ◽  
Substorm Onset ◽  
Significant Development ◽  
H Index ◽  
Magnetospheric Tail ◽  
Storms And Substorms ◽  
Substorm Onsets

Abstract. In order to investigate the causal relationship between magnetic storms and substorms, variations of the mid-latitude geomagnetic indices, ASY (asymmetric part) and SYM (symmetric part), at substorm onsets are examined. Substorm onsets are defined by three different phenomena; (1) a rapid increase in the mid-latitude asymmetric-disturbance indices, ASY-D and ASY-H, with a shape of so-called `mid-latitude positive bay\\'; (2) a sharp decrease in the AL index; (3) an onset of Pi2 geomagnetic pulsation. The positive bays are selected using eye inspection and a pattern-matching technique. The 1-min-resolution SYM-H index, which is essentially the same as the hourly Dst index except in terms of the time resolution, does not show any statistically significant development after the onset of substorms; it tends to decay after the onset rather than to develop. It is suggested by a simple model calculation that the decay of the magnetospheric tail current after substorm onset is responsible for the decay of the Dst field. The relation between the IMF southward turning and the development of the Dst field is re-examined. The results support the idea that the geomagnetic storms and substorms are independent processes; that is, the ring-current development is not the result of the frequent occurrence of substorms, but that of enhanced convection caused by the large southward IMF. A substorm is the process of energy dissipation in the magnetosphere, and its contribution to the storm-time ring-current formation seems to be negligible. The decay of the Dst field after a substorm onset is explained by a magnetospheric energy theorem.

Optimum torrefaction range for Macaw husks aiming its use as a solid biofuel

2021 ◽  
pp. 1-28
Author(s):  
Robson L Silva ◽  
Omar Seye ◽  
Paulo P. S. Schneider
Keyword(s):  
Energy Density ◽  
Mass Loss ◽  
Energy Content ◽  
Residence Times ◽  
Biomass Feedstock ◽  
Severity Factor ◽  
Optimization Criteria ◽  
Residual Biomass ◽  
Solid Biofuel

Abstract Biomass feedstock is broadly available in many countries and a significant amount of residual biomass comes from agriculture and forest crops. This study aims to identify a consistent criteria for optimize Macaw husks torrefaction process maximizing the energy content and minimizing the mass loss. The optimization criteria is based on the Severity Factor (SF), HHVTorrified and ηSolid-Yield. The energy density (ρEnergy) does not provide consistent and indisputable evidence as an optimization criteria; the same applies to Energy-Mass Co-benefit Index (EMCI) and ηEnergy-Yield. This investigation combined few temperatures (180°C, 220°C, and 260°C) with different residence times (20, 40, and 60 min) and found that the optimum torrefaction range for Macaw husk is 220

scholarly journals The ring current: a short biography

2012 ◽  
Vol 3 (2) ◽  
pp. 131-142 ◽  
Author(s):  
A. Egeland ◽  
W. J. Burke
Keyword(s):  
Magnetic Field ◽  
Ring Current ◽  
Energy Content ◽  
Spectral Characteristics ◽  
Direct Access ◽  
Sufficient Evidence ◽  
Mass Spectrometers ◽  
Before And After ◽  
Magnetic Signatures ◽  
Collective Plasma

Abstract. The "ring current'' grows in the inner magnetosphere during magnetic storms and contributes significantly to characteristic perturbations to the Earth's field observed at low-latitudes. This paper outlines how understanding of the ring current evolved during the half-century intervals before and after humans gained direct access to space. Its existence was first postulated in 1910 by Carl Størmer to explain the locations and equatorward migrations of aurorae under stormtime conditions. In 1917 Adolf Schmidt applied Størmer's ring-current hypothesis to explain the observed negative perturbations in the Earth's magnetic field. More than another decade would pass before Sydney Chapman and Vicenzo Ferraro argued for its necessity to explain magnetic signatures observed during the main phases of storms. Both the Størmer and Chapman–Ferraro models had difficulties explaining how solar particles entered and propagated in the magnetosphere to form the ring current. During the early 1950s Hannes Alfvén correctly argued that the ring current was a collective plasma effect, but failed to explain particle entry. The discovery of a weak but persistent interplanetary magnetic field embedded in a continuous solar wind provided James Dungey with sufficient evidence to devise the magnetic merging-reconnection model now regarded as the basis for understanding magnetospheric and auroral activity. In the mid-1960s Louis Frank showed that ions in the newly discovered plasma sheet had the energy spectral characteristics needed to explain the ring current's origin. The introduction of ion mass spectrometers on space missions during the 1970s revealed that O+ ions from the ionosphere contribute large fractions of the ring current's energy content. Precisely how cold O+ ions in the ionosphere are accelerated to ring-current energies still challenges scientific understanding.

Global Distribution of Reversed Energy Spectra of Ring Current Protons Based on Van Allen Probes Observations

2021 ◽  
Vol 48 (4) ◽  
Author(s):  
Juan Yi ◽  
Song Fu ◽  
Binbin Ni ◽  
Xudong Gu ◽  
Man Hua ◽  
...  
Keyword(s):  
Ring Current ◽  
Global Distribution ◽  
Energy Spectra ◽  
Van Allen Probes

Variation of Radiation Belt Electron Flux During CME‐ and CIR‐Driven Geomagnetic Storms: Van Allen Probes Observations

2019 ◽  
Vol 124 (8) ◽  
pp. 6524-6540 ◽  
Author(s):  
Megha Pandya ◽  
Veenadhari Bhaskara ◽  
Yusuke Ebihara ◽  
Shrikanth G. Kanekal ◽  
Daniel N. Baker
Keyword(s):  
Radiation Belt ◽  
Electron Flux ◽  
Geomagnetic Storms ◽  
Van Allen Probes
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