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Synchrotron self-absorption in active galactic nuclei (AGN) jets manifests itself as a time delay between flares observed at high and low radio frequencies. It is also responsible for the observing frequency dependent change in size and…

Astrophysics of Galaxies · Physics 2019-04-17 Alexander Kutkin , Ilya Pashchenko , Kirill Sokolovsky , Yuri Y. Kovalev , Margo Aller , Hugh Aller

Satellite images have become increasingly valuable for modelling regional climate change effects. Earth surface forecasting represents one such task that integrates satellite images with meteorological data to capture the joint evolution of…

Machine Learning · Computer Science 2024-08-13 Tushar Verma , Sudipan Saha

The use of a Numerical Weather Model (NWM) to provide in situ atmosphere information for mapping functions of atmosphere delay has been evaluated using Very Long Baseline Interferometry (VLBI) data spanning eleven years. Parameters required…

Geophysics · Physics 2007-05-23 A. Niell , L. Petrov

The next generation of galaxy surveys like the Dark Energy Spectroscopic Instrument (DESI) and Euclid will provide datasets orders of magnitude larger than anything available to date. Our ability to model nonlinear effects in late time…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-15 Atsuhisa Ota , Hee-Jong Seo , Shun Saito , Florian Beutler

Information storage, reflecting the capability of a dynamical system to keep predictable information during its evolution over time, is a key element of intrinsic distributed computation, useful for the description of the dynamical…

Atmospheric correction is a fundamental task in remote sensing because observations are taken either of the atmosphere or looking through the atmosphere. Atmospheric correction errors can significantly alter the spectral signature of the…

Image and Video Processing · Electrical Eng. & Systems 2022-03-23 Fangcao Xu , Jian Sun , Guido Cervone , Mark Salvador

Global data assimilation enables weather forecasting at all scales and provides valuable data for studying the Earth system. However, the computational demands of physics-based algorithms used in operational systems limits the volume and…

Machine Learning · Computer Science 2024-07-17 Thomas J. Vandal , Kate Duffy , Daniel McDuff , Yoni Nachmany , Chris Hartshorn

We have studied Very Long Baseline Array (VLBA) polarimetric observations of 8 sources including quasars and BL Lacs at 12, 15, 22, 24 and 43 GHz and high frequency rotation measure ($RM$) maps are presented. We find typical values for the…

High Energy Astrophysical Phenomena · Physics 2015-06-12 J. C. Algaba

Space Very-Long-Baseline-Interferometry (S-VLBI) observations at high frequencies hold the prospect of achieving the highest angular resolutions and astrometric accuracies, resulting from the long baselines between ground and satellite…

Instrumentation and Methods for Astrophysics · Physics 2012-01-12 M. Rioja , R. Dodson , J. Malarecki , Y. Asaki

The application of Very Long Baseline Interferometry (VLBI) to the Search for Extraterrestrial Intelligence (SETI) has been limited to date, despite the technique offering many advantages over traditional single-dish SETI observations. In…

The wavelength dependence of atmospheric refraction causes elongation of finite-bandwidth images along the elevation vector, which produces spurious signals in weak gravitational lensing shear measurements unless this atmospheric dispersion…

Instrumentation and Methods for Astrophysics · Physics 2015-06-04 Andrés A. Plazas , Gary M. Bernstein

We present results of a pilot observational wide-field VLBI campaign on probing scattering properties of the partly ionized interstellar medium towards the Galactic plane sky region between $28^\circ<l<36^\circ$ and $|b|<1^\circ$. This…

Seeing the Earth crust as crisscrossed by faults filled with fluid at close to lithostatic pressures, we develop a model in which its elastic modulii are different in net tension versus compression. In constrast with standard nonlinear…

Geophysics · Physics 2007-05-23 G. Ouillon , D. Sornette

5,000,000 VLBI delays are stored now in the IVS data base and available for scientific analysis. This is a remarkable result of more than 20 years of geodetic VLBI history. This paper presents some statistics related to the VLBI…

Geophysics · Physics 2011-02-04 Zinovy Malkin

A likely source of earthquake clustering is static stress transfer between individual events. Previous attempts to quantify the role of static stress for earthquake triggering generally considered only the stress changes caused by large…

Geophysics · Physics 2017-06-28 Shyam Nandan , Guy Ouillon , Jochen Woessner , Didier Sornette , Stefan Wiemer

Machine learning (ML) is often viewed as a black-box regression technique that is unable to provide considerable scientific insight. ML models are universal function approximators and - if used correctly - can provide scientific information…

We have carried out full imaging simulation studies to explore the impact of frequency standards in millimeter and sub-millimeter Very Long Baseline Interferometry (VLBI), focusing on the coherence time and sensitivity. In particular, we…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 M. Rioja , R. Dodson , Y. Asaki , J. Hartnett , S. Tingay

VLBI is unique, among the space geodetic techniques, in its contribution to defining and maintaining the International Celestial Reference Frame, providing precise measurements of coordinates of extragalactic radiosources. The quest for…

Atmospheric modeling has recently experienced a surge with the advent of deep learning. Most of these models, however, predict concentrations of pollutants following a data-driven approach in which the physical laws that govern their…

Applications · Statistics 2021-07-08 Javier Rubio-Herrero , Carlos Ortiz Marrero , Wai-Tong Louis Fan

We present images from a space-VLBI survey using the facilities of the VLBI Space Observatory Programme (VSOP), drawing our sample from the well-studied Pearson-Readhead survey of extragalactic radio sources. Our survey has taken advantage…

Astrophysics · Physics 2009-11-06 M. L. Lister , S. J. Tingay , D. W. Murphy , B. G. Piner , D. L. Jones , R. A. Preston