scholarly journals GGOS Focus Area on Geodetic Space Weather Research – Current Status

Author(s):  
Michael Schmidt ◽  
Ehsan Forootan

<p>Space weather means a very up-to-date and interdisciplinary field of research. It describes physical processes in space mainly caused by the Sun’s radiation of energy. The manifestations of space weather are multiple, for instance, the variations of the Earth’s magnetic field or the changing states of the upper atmosphere, in particular the ionosphere and the thermosphere.</p><p>The main objectives of the Focus Area on Geodetic Space Weather Research (FA GSWR) are (1) the development of improved ionosphere models, (2) the development of improved thermosphere models and (3) the study of the coupled processes between magnetosphere, ionosphere and thermosphere (MIT). </p><p>Objective (1) aims at the high-precision and the high-resolution (spatial and temporal) modelling of the electron density. This allows to compute a signal propagation delay, which will be used in many geodetic applications, in particular in positioning, navigation and timing (PNT). Moreover, it is also important for other techniques using electromagnetic waves, such as satellite- or radio-communications. Concerning objective (2), satellite geodesy will obviously benefit when working on Precise Orbit Determination (POD), but there are further technical matters like collision analysis or re-entry calculation, which will become more reliable when using high-precision and high-resolution thermospheric drag models. Objective (3) links the magnetosphere with the first two objectives by introducing physical laws and principles such as continuity, energy and momentum equations and solving partial differential equations.     </p><p>To arrive at the above described objectives of the FA GSWR one new Joint Study Groups (JSG) and three Joint Working Groups (JWG) have been installed recently. In detail, these groups are titled as JSG 1: Coupling processes between magnetosphere, thermosphere and ionosphere, JWG 1: Electron density modelling, JWG 2: Improvement of thermosphere models, and JWG 3: Improved understanding of space weather events and their monitoring by satellite missions. Other implemented IAG Study and Working Groups within the IAG programme 2019 to 2023 will provide valuable input for the FA GSWR. In this presentation we provide the latest investigations and results from the above mentioned Joint Study and Working Groups JSG 1, JWG 1, JWG 2 and JWG 3 of the FA GSWR.</p>

Physica ◽  
1952 ◽  
Vol 18 (2) ◽  
pp. 1063-1065 ◽  
Author(s):  
R SIDAY

Author(s):  
Eaton E. Lattman ◽  
Thomas D. Grant ◽  
Edward H. Snell

Direct electron density determination from SAXS data opens up new opportunities. The ability to model density at high resolution and the implicit direct estimation of solvent terms such as the hydration shell may enable high-resolution wide angle scattering data to be used to calculate density when combined with additional structural information. Other diffraction methods that do not measure three-dimensional intensities, such as fiber diffraction, may also be able to take advantage of iterative structure factor retrieval. While the ability to reconstruct electron density ab initio is a major breakthrough in the field of solution scattering, the potential of the technique has yet to be fully uncovered. Additional structural information from techniques such as crystallography, NMR, and electron microscopy and density modification procedures can now be integrated to perform advanced modeling of the electron density function at high resolution, pushing the boundaries of solution scattering further than ever before.


Energy ◽  
2021 ◽  
pp. 121047
Author(s):  
Kunal K. Dayal ◽  
Gilles Bellon ◽  
John E. Cater ◽  
Michael J. Kingan ◽  
Rajnish N. Sharma

2001 ◽  
Vol 34 (2) ◽  
pp. 214-223 ◽  
Author(s):  
Benoit Guillot ◽  
Laurence Viry ◽  
Regis Guillot ◽  
Claude Lecomte ◽  
Christian Jelsch

Crystallography at subatomic resolution permits the observation and measurement of the non-spherical character of the atomic electron density. Charge density studies are being performed on molecules of increasing size. TheMOPROleast-squares refinement software has thus been developed, by extensive modifications of the programMOLLY, for protein and supramolecular chemistry applications. The computation times are long because of the large number of reflections and the complexity of the multipolar model of the atomic electron density; the structure factor and derivative calculations have thus been parallelized. Stereochemical and dynamical restraints as well as the conjugate gradient algorithm have been implemented. A large number of the normal matrix off-diagonal terms turn out to be very small and the block diagonal approximation is thus particularly efficient in the case of large structures at very high resolution.


2020 ◽  
Author(s):  
Angelos Vourlidas ◽  
Justin Likar ◽  
Viacheslav Merkin ◽  
Romina Nikoukar ◽  
Larry Paxton ◽  
...  

2019 ◽  
Vol 2019 (6) ◽  
pp. 875-884 ◽  
Author(s):  
Maxim G. Chegerev ◽  
Alexandr V. Piskunov ◽  
Kseniya V. Tsys ◽  
Andrey G. Starikov ◽  
Klaus Jurkschat ◽  
...  

2018 ◽  
Vol 61 (7) ◽  
pp. 1636-1651 ◽  
Author(s):  
C. Martinis ◽  
J. Baumgardner ◽  
J. Wroten ◽  
M. Mendillo

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