Thermospheric Neutral Winds: A Driver of the Earth’s Inner Radiation Belt to Be Reckoned With

2021 ◽  
Author(s):  
Solène Lejosne ◽  
Naomi Maruyama ◽  
Richard S. Selesnick ◽  
Mariangel Fedrizzi
Keyword(s):  
Electric Fields ◽  
Radiation Belt ◽  
Coupled Model ◽  
Plasma Dynamics ◽  
Time Asymmetry ◽  
Neutral Winds ◽  
Tidal Motion ◽  
The Earth ◽  
Field Lines ◽  
The Impact

<p>Neutral winds have long been viewed as a driver of Jupiter’s radiation belts. On the other hand, the impact of thermospheric neutral winds in driving plasma dynamics in the Earth’s inner magnetosphere is yet to be quantified. We now have the appropriate combination of data and physics-based model to address this fundamental science question.</p><p>In this work, we revisit the local time asymmetry of the equatorial electron intensity observed in the innermost radiation belt (L=1.30). We combine in-situ field and particle observations, together with a physics-based coupled model, RCM-CTIPe, to determine whether the dynamo electric fields produced by tidal motion of upper atmospheric winds flowing across the Earth’s magnetic field lines are the main drivers of the drift-shell distortion observed in the Earth’s inner radiation belt.</p><p>Our results provide a first quantification of the contribution of the neutral wind in transporting the trapped energetic particles of the Earth’s inner radiation belt.</p>

The GMAO High‐Resolution Coupled Model and Assimilation System for Seasonal Prediction

2021 ◽  
Author(s):  
Andrea Molod ◽  
Keyword(s):  
Coupled Model ◽  
Seasonal Prediction ◽  
Earth System ◽  
Aerosol Model ◽  
Earth Observing System ◽  
The North ◽  
The Earth ◽  
Weakly Coupled ◽  
The North Atlantic Oscillation ◽  
The Impact

<p>The Global Modeling and Assimilation Office (GMAO) is about to release a new version of the Goddard Earth Observing System (GEOS) Subseasonal to Seasonal prediction (S2S) system, GEOS‐S2S‐3, that represents an improvement in performance and infrastructure over the  previous system, GEOS-S2S-2. The system will be described briefly, highlighting some features unique to GEOS-S2S, such as the coupled interactive aerosol model and ensemble  perturbation strategy and size. Results are presented from forecasts and from climate  equillibrium simulations. GEOS-S2S-3 will be used to produce a long term weakly coupled reanalysis called MERRA-2 Ocean.</p><p>The climate or equillibrium state of the atmosphere and ocean shows a reduction in systematic error relative to GEOS‐S2S‐2, attributed in part to an increase in ocean resolution and to the upgrade in the glacier runoff scheme.  The forecast skill shows improved prediction  of the North Atlantic Oscillation, attributed to the increase in forecast ensemble members.  </p><p>With the release of GEOS-S2S-3 and MERRA-2 Ocean, GMAO will continue its tradition of maintaining a state‐of‐the‐art seasonal prediction system for use in evaluating the impact on seasonal and decadal forecasts of assimilating newly available satellite observations, as well as evaluating additional sources of predictability in the Earth system through the expanded coupling of the Earth system model and assimilation components.</p>

scholarly journals Storm-time meridional flows: a comparison of CINDI observations and model results

2014 ◽  
Vol 32 (6) ◽  
pp. 659-668 ◽  
Author(s):  
M. Hairston ◽  
N. Maruyama ◽  
W. R. Coley ◽  
R. Stoneback
Keyword(s):  
Electric Field ◽  
Geomagnetic Storm ◽  
Electric Fields ◽  
Previous Analysis ◽  
Coupled Model ◽  
Polar Ionosphere ◽  
Inner Magnetosphere ◽  
Ion Flow ◽  
The Earth ◽  
Coupling Processes

Abstract. During a large geomagnetic storm, the electric field from the polar ionosphere can expand far enough to affect the mid-latitude and equatorial electric fields. These changes in the equatorial zonal electric field, called the penetration field, will cause changes in the meridional ion flows that can be observed by radars and spacecraft. In general this E × B ion flow near the equator caused by the penetration field during undershielding conditions will be upward on the dayside and downward on the nightside of the Earth. Previous analysis of the equatorial meridional flows observed by CINDI instrument on the C/NOFS spacecraft during the 26 September 2011 storm showed that all of the response flows on the dayside were excess downward flows instead of the expected upward flows. These observed storm-time responses are compared to a prediction from a physics-based coupled model of thermosphere–ionosphere–inner-magnetosphere in an effort to explain these observations. The model results suggest that the equatorial downward flow could be attributed to a combined effect of the overshielding and disturbance dynamo processes. However, some discrepancy between the model and observation indicates a need for improving our understanding of how sensitive the equatorial electric field is to various model input parameters that describe the magnetosphere–ionosphere coupling processes.

scholarly journals Calculation of meridional neutral winds in middle latitudes from the Irkutsk incoherent scatter radar data

2015 ◽  
Vol 1 (3) ◽  
pp. 37-48
Author(s):  
Александр Щербаков ◽  
Aleksandr Shcherbakov ◽  
Андрей Медведев ◽  
Andrey Medvedev ◽  
Дмитрий Кушнарев ◽  
...  
Keyword(s):  
Electric Fields ◽  
Radar Data ◽  
Special Technique ◽  
Incoherent Scatter Radar ◽  
Neutral Winds ◽  
Incoherent Scatter ◽  
Plasma Drift ◽  
Middle Latitudes ◽  
Scatter Radar ◽  
The Impact

The paper sequentially presents technique for determining velocity of meridional neutral winds from the Irkutsk Incoherent Scatter Radar (IISR) data. Due to IISR specific features effective at other IS radars, techniques for determining ionosphere parameters, in particular plasma drift velocities, resulted in considerable variance of defined parameters. To measure the plasma drift velocity taking into account such IISR features, we have developed a special technique based on phase analysis of autocorrelation function of incoherent scatter signal. The technique needs to be tested, and for this purpose, an experiment was carried out to measure velocities of low-orbit satellites. However, methods for meridional neutral wind calculations used by many authors [Evans, 1970] with the use of drift velocities obtained before, resulted in great disagreements with empirical HWM93 and HWM07 wind models. In addition, simultaneous measurements at two frequencies at IISR showed that it was difficult to explain such differences without taking into account the cross-field movements. Possible underestimation of the impact of movements generated by electric fields can result in serious error in determining wind velocities. The paper considers improvements for methods of calculating winds, and shows that the results obtained with it are in a better agreement with wind models.

The Plasmasphere During Major Geomagnetic Storms: Analysis Of Trapped Particles In The Outer Radiation Belt

2020 ◽  
Author(s):  
Jessy Matar ◽  
Benoit Hubert ◽  
Stan Cowley ◽  
Steve Milan ◽  
Zhonghua Yao ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Geomagnetic Field ◽  
Radiation Belt ◽  
Ring Current ◽  
Geomagnetic Storms ◽  
Outer Radiation Belt ◽  
Trapped Particles ◽  
The Earth ◽  
Field Lines

<p> The coupling between the Earth’s magnetic field and the interplanetary magnetic field (IMF) transported by the solar wind results in a cycle of magnetic field lines opening and closing generally known as the Dungey substorm cycle, mostly governed by the process of magnetic reconnection. The geomagnetic field lines can therefore have either a closed or an open topology, i.e. lower latitude field lines are closed (map from southern ionosphere to the northern), while higher latitude field lines are open (map from one polar ionosphere into interplanetary space). Closed field lines can trap electrically charged particles that bounce between mirror points located in the North and South hemispheres while drifting in longitude around the Earth, forming the plasmasphere, the radiation belts and the ring current. The outer boundary of the plasmasphere is the plasmapause. Its location is mostly driven by the interplay of the corotation electric field of ionospheric origin, and the convection electric field that results from the interaction between the IMF and the geomagnetic field. At times of prolonged intense coupling between these fields, the response of the magnetosphere becomes global and a geomagnetic storm develops. The ring current created by the motion of the trapped energetic particles intensifies and then decays as the storm abates. This study aims to find a possible relationship between the evolution of the trapped population and the process of magnetic reconnection during storm times. The EUV instrument on board the NASA-IMAGE spacecraft observed the distribution of the trapped helium ions (He+) in the plasmasphere. We consider several cases of intense geomagnetic storms observed by the IMAGE satellite. We identify the plasmapause location (Lpp) during those cases. We find a strong correlation between the Dst index and Lpp. The ring current and the trapped particles are expected to vary during storms. We use the Tsyganenko magnetic field model to map the electric potential between the Heppner-Maynard boundary (HMB) in the ionosphere and the magnetosphere and estimate the voltage and electric field in the vicinity of the plasmapause. The ionospheric electric field is deduced from the ionospheric convection velocity measured by the SuperDARN (SD) radar network at high latitudes. The tangential electric field component of the moving plasmapause boundary is estimated from IMAGE-EUV observations of the plasmasphere and is compared with expectations based on the SD data. We combine measurements of the trapped population from IMAGE-EUV and IMAGE-FUV observations of the aurora to better understand and quantify the variability of the Earth's outer radiation belt during strong storms. The auroral precipitation at ionospheric latitude is studied using FUV imaging and compared to the He+ response during the storms.</p>

The Magnetospheric “Zebra Stripes”: A Tracer of Near-Earth Space Dynamics

2021 ◽  
Author(s):  
Solène Lejosne ◽  
Forrest S. Mozer
Keyword(s):  
Electric Fields ◽  
Radiation Belt ◽  
Periodic Structures ◽  
High Energy ◽  
High Energy Resolution ◽  
Stripe Pattern ◽  
Near Earth Space ◽  
The Earth ◽  
Space Dynamics ◽  
First Time

<p>High-energy resolution measurements of energetic (tens to hundreds of keV) electron fluxes in the Earth’s inner radiation belt and slot region (below L~ 3) revealed the presence of drift-periodic structures named the “zebra stripes”.</p><p>We show that analyzing the characteristics of the zebra stripes provides a new tool to shed light on important, yet mostly uncharted drivers of the Earth’s inner magnetosphere, namely, (a) radial displacements of geomagnetically trapped particles in the inner belt and slot region, and (b) electric field variations in the subauroral region.</p><p>With the large database of high-quality observations provided by the NASA Van Allen Probes mission, it is for the first time possible to perform long-term statistical analysis of the zebra stripe pattern.</p><p>Because Earth-like zebra stripes were also recently discovered at Saturn, the analysis of the zebra stripes present at Earth could constitute a benchmark to determine the electric fields and associated radiation belt dynamics at other magnetized planets.</p>

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

scholarly journals Impact of air–sea coupling on the climate change signal over the Iberian Peninsula

2021 ◽  
Author(s):  
Alba de la Vara ◽  
William Cabos ◽  
Dmitry V. Sein ◽  
Claas Teichmann ◽  
Daniela Jacob
Keyword(s):  
Climate Change ◽  
Iberian Peninsula ◽  
Mediterranean Sea ◽  
Large Scale ◽  
Regional Distribution ◽  
Coupled Model ◽  
Climate Change Signal ◽  
The North ◽  
The Mediterranean ◽  
The Impact

AbstractIn this work we use a regional atmosphere–ocean coupled model (RAOCM) and its stand-alone atmospheric component to gain insight into the impact of atmosphere–ocean coupling on the climate change signal over the Iberian Peninsula (IP). The IP climate is influenced by both the Atlantic Ocean and the Mediterranean sea. Complex interactions with the orography take place there and high-resolution models are required to realistically reproduce its current and future climate. We find that under the RCP8.5 scenario, the generalized 2-m air temperature (T2M) increase by the end of the twenty-first century (2070–2099) in the atmospheric-only simulation is tempered by the coupling. The impact of coupling is specially seen in summer, when the warming is stronger. Precipitation shows regionally-dependent changes in winter, whilst a drier climate is found in summer. The coupling generally reduces the magnitude of the changes. Differences in T2M and precipitation between the coupled and uncoupled simulations are caused by changes in the Atlantic large-scale circulation and in the Mediterranean Sea. Additionally, the differences in projected changes of T2M and precipitation with the RAOCM under the RCP8.5 and RCP4.5 scenarios are tackled. Results show that in winter and summer T2M increases less and precipitation changes are of a smaller magnitude with the RCP4.5. Whilst in summer changes present a similar regional distribution in both runs, in winter there are some differences in the NW of the IP due to differences in the North Atlantic circulation. The differences in the climate change signal from the RAOCM and the driving Global Coupled Model show that regionalization has an effect in terms of higher resolution over the land and ocean.

scholarly journals Peculiarities of Neurostimulation by Intense Nanosecond Pulsed Electric Fields: How to Avoid Firing in Peripheral Nerve Fibers

2021 ◽  
Vol 22 (13) ◽  
pp. 7051
Author(s):  
Vitalii Kim ◽  
Emily Gudvangen ◽  
Oleg Kondratiev ◽  
Luis Redondo ◽  
Shu Xiao ◽  
...  
Keyword(s):  
Side Effects ◽  
Electric Fields ◽  
Pulsed Electric Fields ◽  
Opposite Polarity ◽  
Nerve Fibers ◽  
High Rate ◽  
Excitation Threshold ◽  
Compound Action Potentials ◽  
Supramaximal Stimulation ◽  
The Impact

Intense pulsed electric fields (PEF) are a novel modality for the efficient and targeted ablation of tumors by electroporation. The major adverse side effects of PEF therapies are strong involuntary muscle contractions and pain. Nanosecond-range PEF (nsPEF) are less efficient at neurostimulation and can be employed to minimize such side effects. We quantified the impact of the electrode configuration, PEF strength (up to 20 kV/cm), repetition rate (up to 3 MHz), bi- and triphasic pulse shapes, and pulse duration (down to 10 ns) on eliciting compound action potentials (CAPs) in nerve fibers. The excitation thresholds for single unipolar but not bipolar stimuli followed the classic strength–duration dependence. The addition of the opposite polarity phase for nsPEF increased the excitation threshold, with symmetrical bipolar nsPEF being the least efficient. Stimulation by nsPEF bursts decreased the excitation threshold as a power function above a critical duty cycle of 0.1%. The threshold reduction was much weaker for symmetrical bipolar nsPEF. Supramaximal stimulation by high-rate nsPEF bursts elicited only a single CAP as long as the burst duration did not exceed the nerve refractory period. Such brief bursts of bipolar nsPEF could be the best choice to minimize neuromuscular stimulation in ablation therapies.

scholarly journals Evaluation of a Coupled Model to Predict the Impact of Adaptive Behaviour in the Thermal Sensation of Occupants of Naturally Ventilated Buildings in Warm-Humid Regions

2020 ◽  
Vol 13 (1) ◽  
pp. 255
Author(s):  
Luciano C. de Faria ◽  
Marcelo A. Romero ◽  
Lúcia F. S. Pirró
Keyword(s):  
Computational Models ◽  
Thermal Sensation ◽  
Coupled Model ◽  
Adaptive Behaviour ◽  
Humid Climate ◽  
Clothing Insulation ◽  
Tropical Regions ◽  
Naturally Ventilated Buildings ◽  
Adaptive Behaviours ◽  
The Impact

Improving indoor environment quality and making urban centres in tropical regions more sustainable has become a challenge for which computational models for the prediction of thermal sensation for naturally ventilated buildings (NVBs) have major role to play. This work performed analysis on thermal sensation for non-residential NVBs located in Brazilian tropical warm-humid climate and tested the effectiveness of suggested adaptive behaviours to mitigate warm thermal sensation. The research method utilized transient computational fluid dynamics models coupled with a dynamic model for human thermophysiology to predict thermal sensation. The calculated results were validated with comparison with benchmark values from questionnaires and from field measurements. The calculated results for dynamic thermal sensation (DTS) seven-point scale showed higher agreement with the thermal sensation vote than with the predicted mean vote. The test for the suggested adaptive behaviours considered reducing clothing insulation values from 0.18 to 0.32 clo (reducing DTS from 0.1 to 0.9), increasing the air speed in 0.9 m/s (reducing DTS from 0.1 to 0.9), and applying both suggestions together (reducing DTS from 0.1 to 1.3) for five scenarios with operative temperatures spanning 34.5–24.0 °C. Results quantified the tested adaptive behaviours’ efficiency showing applicability to improve thermal sensation from slightly-warm to neutral.

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