scholarly journals Evolution of the dispersionless injection boundary associated with substorms

2005 ◽  
Vol 23 (3) ◽  
pp. 877-884 ◽  
Author(s):  
T. Sarris ◽  
X. Li
Keyword(s):  
Leading Edge ◽  
Transport Processes ◽  
Pulse Field ◽  
Magnetospheric Substorms ◽  
Narrow Region ◽  
The Earth ◽  
Electric And Magnetic Fields ◽  
Sudden Appearance ◽  
Injection Region ◽  
Multiple Spacecraft

Abstract. One manifestation of energetic particle acceleration during magnetospheric substorms is the sudden appearance of particle injections into the inner magnetosphere, often observed near geosynchronous orbit. Injections that show simultaneous flux increases in all energy ranges of a detector are called dispersionless injections, and are most often observed in a narrow region around local midnight. In these events it is assumed that the satellite is located close to or inside the region where acceleration and/or transport processes are taking place, called the injection region. We present a study of the location, extent and temporal evolution of the injection region, based on simulation results of a model of the expansion of the electric and magnetic fields associated with a substorm. The model simulates the fields during a substorm onset with an electric field and consistent magnetic field pulse that propagates towards the Earth with a decreasing speed. Our simulation shows that the dispersionless injection boundary can be considered coincident with the leading edge of the pulse field, which transports particles toward the Earth across a certain range of local time. Under the same model field, the dispersionless injection boundary shifts eastward for electrons and westward for protons, consistent with the observation results deduced from statistical analysis of multiple spacecraft measurements.

Future Gravity Mission Concepts for Sustained Observation of Mass Transport in the Earth System

2021 ◽  
Author(s):  
Roland Pail
Keyword(s):  
Mass Transport ◽  
Closed Loop ◽  
Cold Atom ◽  
Radial Component ◽  
Transport Processes ◽  
Single Pair ◽  
Earth System ◽  
Next Generation ◽  
The Earth ◽  
Gravity Mission

<p>Next Generation Gravity Missions are expected to enhance our knowledge of mass transport processes in the Earth system, establishing their products applicable to new scientific fields and serving societal needs. Compared to the current situation (GRACE Follow-On), a significant step forward to increase spatial and temporal resolution can only be achieved by new mission concepts, complemented by improved instrumentation and tailored processing strategies.</p><p>In extensive numerical closed-loop mission simulations studies, different mission concepts have been studied in detail, with emphasis on orbit design and resulting spatial-temporal ground track pattern, enhances processing and parameterization strategies, and improved post-processing/filtering strategies. Promising candidates for a next-generation gravity mission are double-pair and multi-pair constellations of GRACE/GRACE-FO-type satellites, as they are currently jointly studied by ESA and NASA. An alternative concept is high-precision ranging between high- and low-flying satellites. Since such a constellation observes mainly the radial component of gravity-induced orbit perturbations, the error structure is close to isotropic, which significantly reduces artefacts of along-track ranging formations. This high-low concept was proposed as ESA Earth Explorer 10 mission MOBILE and is currently further studies under the name MARVEL by the French space agency. Additionally, we evaluate the potential of a hybridization of electro-static and cold-atom accelerometers in order to improve the accelerometer performance in the low-frequency range.</p><p>In this contribution, based on full-fledged numerical closed-loop simulations with realistic error assumptions regarding their key payload, different mission constellations (in-line single-pair, Bender double-pair, multi-pairs, precise high-low tracking) are assessed and compared. Their overall performance, dealiasing potential, and recovery performance of short-periodic gravity signals are analyzed, in view of their capabilities to retrieve gravity field information with short latencies to be used for societally relevant service applications, such as water management, groundwater monitoring, and forecasting of droughts and floods.</p>

The Earth: Plasma Sources, Losses, and Transport Processes

2016 ◽  
pp. 145-208 ◽  
Author(s):  
Daniel T. Welling ◽  
Mats André ◽  
Iannis Dandouras ◽  
Dominique Delcourt ◽  
Andrew Fazakerley ◽  
...  
Keyword(s):  
Transport Processes ◽  
Plasma Sources ◽  
The Earth

Recovering climate-related mass transport signals by current and next-generation gravity missions

2020 ◽  
Author(s):  
Roland Pail ◽  
Henryk Dobslaw ◽  
Annette Eicker ◽  
Laura Jensen
Keyword(s):  
Climate Change ◽  
Time Series ◽  
Mass Transport ◽  
Gravity Field ◽  
Transport Processes ◽  
Measuring System ◽  
Climate Projections ◽  
Earth System ◽  
Next Generation ◽  
The Earth

<p>Gravity field missions are a unique geodetic measuring system to directly observe mass transport processes in the Earth system. Past and current gravity missions such as CHAMP, GRACE, GOCE and GRACE-Follow On have improved our understanding of large-scale mass changes, such as the global water cycle, melting of continental ice sheets and mountain glaciers, changes in ocean mass that are closely related to the mass-related component of sea level rise, which are subtle indicators of climate change, on global to regional scale. Therefore, mass transport observations are also very valuable for long-term climate applications. Next Generation Gravity Missions (NGGMs) expected to be launched in the midterm future have set high anticipations for an enhanced monitoring of mass transport in the Earth system with significantly improved spatial and temporal resolution and accuracy. This contribution will present results from numerical satellite mission performance simulations designed to evaluate the usefulness of gravity field missions operating over several decades for climate-related applications. The study is based on modelled of mass transport time series obtained from future climate projections until the year 2100 following the representative emission pathway RCP8.5 Numerical closed-loop simulations will assess the recoverability of mass variability signals by means of different NGGM concepts, e.g. GRACE-type in-line single-pair missions, Bender double-pair mission being composed of a polar and an inclined satellite pair, or high-precision high-low tracking missions following the MOBILE concept, assuming realistic noise levels for the key payload. In the evaluation and interpretation of the results, special emphasis shall be given to the identification of (natural or anthropogenic) climate change signals in dependence of the length of the measurement time series, and the quantification of robustness of derived trends and systematic changes.</p>

First solar electron events observed by EPD aboard Solar Orbiter

2021 ◽  
Author(s):  
Raúl Gómez-Herrero ◽  
Daniel Pacheco ◽  
Alexander Kollhoff ◽  
Francisco Espinosa Lara ◽  
Johan L. Freiherr von Forstner ◽  
...  
Keyword(s):  
Heavy Ions ◽  
Extreme Ultraviolet ◽  
Transport Processes ◽  
Relativistic Electrons ◽  
Radio Bursts ◽  
Solar Origin ◽  
Time Profiles ◽  
Field Environment ◽  
Multiple Spacecraft ◽  
Excellent Energy Resolution

<p>The first solar electron events detected by Solar Orbiter were observed by the Energetic Particle Detector (EPD) suite during July 11-23, 2020, when the spacecraft was at heliocentric distances between 0.61 and 0.69 au. We combined EPD electron observations from 4 keV to the relativistic range (few MeV), radio dynamic spectra and extreme ultraviolet (EUV) observations from multiple spacecraft in order to identify the solar origin of these electron events. Electron anisotropies and timing as well as the plasma and magnetic field environment were evaluated to characterize the interplanetary transport conditions. We found that all the electron events were clearly associated with type III radio bursts. EUV jets were also found in association with all of them except one. A diversity of time profiles and pitch-angle distributions (ranging from almost isotropic to beam-like) was observed. These observations indicate that different source locations and different magnetic connectivity and transport conditions were likely involved. The broad spectral range covered by EPD with excellent energy resolution and the high time cadence ensure that future observations close to the Sun will contribute to the understanding of the acceleration, release, and transport processes of energetic particles. EPD observations will play a key role in the identification of the sources of impulsive events and the links between the near-relativistic electrons and the ion populations enriched in <sup>3</sup>He and heavy ions</p><p> </p>

Foundation News: Pay it forward — The SEG Foundation in 2021

2021 ◽  
Vol 40 (3) ◽  
pp. 168-169
Author(s):  
Katie Burk
Keyword(s):  
Leading Edge ◽  
Professional Community ◽  
Professional Activities ◽  
The Earth ◽  
The People ◽  
The World

The people of SEG are on the leading edge of geophysics and geoscience and are focused on making life safer and more fulfilling for populations in every corner of the earth. This work is accomplished by reviewing papers and abstracts, serving on grant and program committees, developing and administering student and professional activities and programs, and participating in strategic discussions for the Society. Members make much of this possible, and contributions to the SEG Foundation fund many of the programs and activities that benefit not only our professional community but communities of people around the world.

Heat-transport processes in the Earth

Geology ◽  
1979 ◽  
Vol 7 (5) ◽  
pp. 267
Author(s):  
James W. Mercer ◽  
Charles R. Faust
Keyword(s):  
Heat Transport ◽  
Transport Processes ◽  
The Earth

THE ELECTRIC AND MAGNETIC FIELDS AT THE SURFACE OF A FLAT CONDUCTING EARTH IN THE NEAR FIELD OF AN OSCILLATING LINE CURRENT

1966 ◽  
Vol 44 (8) ◽  
pp. 1923-1931 ◽  
Author(s):  
H. W. Dosso
Keyword(s):  
Magnetic Fields ◽  
Near Field ◽  
Numerical Calculations ◽  
Line Current ◽  
The Earth ◽  
Electric And Magnetic Fields ◽  
Phase Angles

The electric and magnetic fields at the surface of a flat conducting earth in the near field of an oscillating line current are studied in this work. The equations for the amplitudes and phase angles developed by Law and Fannin (1961) were used for the numerical calculations. The source heights (h = 105 to 4 × 105 meters), the source frequencies (ƒ = 10−3 to 10 sec−1), and the earth conductivities (σ = 10−5 to 10 mho/m) considered are of interest in geophysics.

scholarly journals Propagation of ELF Radiation from RS-LC System and Red Sprites in Earth-Ionosphere Waveguide

2012 ◽  
Vol 1 (2) ◽  
pp. 96
Author(s):  
M. K. Paras ◽  
J. Rai
Keyword(s):  
Magnetic Fields ◽  
Return Stroke ◽  
Schumann Resonances ◽  
The Earth ◽  
Electric And Magnetic Fields ◽  
Red Sprites

In this paper, two different mechanisms return stroke-lateral corona (RS-LC) system and red sprites which excite Earth-ionosphere waveguide have been discussed. The electric and magnetic fields from RS-LC system and red spites in the Earth-ionosphere waveguide have been calculated. It has been found that red sprites contribute to the Schumann resonances (SR) greatly as compared to the RS-LC system.

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