Výsledky vyhledávání

Electrodynamics of an omega-band as deduced from optical and magnetometer data

Autor: Olaf Amm, Heikki Vanhamäki, Dirk Lummerzheim, Kirsti Kauristie, Andrew Senior, S. Milan

Publikováno v: Annales Geophysicae, Vol 27, Pp 3367-3385 (2009)
Annales Geophysicae, Vol 27, Iss 9, Pp 3367-3385 (2009)

We investigate an omega-band event that took place above northern Scandinavia around 02:00–02:30 UT on 9 March 1999. In our analysis we use ground based magnetometer, optical and riometer measurements together with satellite based optical images. T

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::56952c917013eb17c1b0d3c209787fdd
https://www.ann-geophys.net/27/3367/2009/

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Comparison of the open-closed field line boundary location inferred using IMAGE-FUV SI12 images and EISCAT radar observations

Autor: Jean-Claude Gérard, Anita Aikio, Kirsti Kauristie, Timo Pitkänen, Olaf Amm, S. Milan, Stan W. H. Cowley, Benoît Hubert

Publikováno v: Annales Geophysicae, Vol 28, Pp 883-892 (2010)

We compare the location of the polar cap boundary (PCB) determined using two different techniques, and use them as proxies for the open-closed field line boundary (OCB). Electron temperatures from observations of the EISCAT radar facility are used to

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2d4a6ea94f18b84d974c70a93597f3a0
https://www.ann-geophys.net/28/883/2010/

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Ionospheric currents estimated simultaneously from CHAMP satelliteand IMAGE ground-based magnetic field measurements: a statisticalstudy at auroral latitudes

Autor: Ari Viljanen, I. Sillanpää, Hermann Lühr, Antti Pulkkinen, Olaf Amm, Patricia Ritter

Publikováno v: Annales Geophysicae, Vol 22, Pp 417-430 (2004)
Annales Geophysicae, Vol 22, Iss 2, Pp 417-430 (2004)

One important contribution to the magnetic field measured at satellite altitude and at ground level comes from the external currents. We used the total field data sampled by the Overhauser Magnetometer on CHAMP and the horizontal magnetic field measu

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::d94a07cf63dede4b08f164847d4eff4b
https://www.ann-geophys.net/22/417/2004/

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An interpretation of spacecraft and ground based observations of multiple omega band events

Autor: Olaf Amm, Adrian Grocott, Robert J. Redmon, Vassilis Angelopoulos, J. Barker-Ream, Harald U. Frey, Margaret G. Kivelson, James M. Weygand, Juan V. Rodriguez

Publikováno v: Journal of Atmospheric and Solar-Terrestrial Physics. 133:185-204

The source of the auroral phenomenon known as omega bands is not yet known. We examine in detail five different intervals when omega bands were observed on March 9th, 2008 between 0400 UT and 1100 UT over central Canada using both ground and space-ba

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::a92aead62b48c994952c693acdabf51d
https://doi.org/10.1016/j.jastp.2015.08.014

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Ionospheric tomography in Bayesian framework with Gaussian Markov random field priors

Autor: L j Johannes Norberg, Juha Vierinen, Lassi Roininen, D. McKay-Bukowski, Olaf Amm, Markku Lehtinen

Publikováno v: Radio Science. 50:138-152

We present a novel ionospheric tomography reconstruction method. The method is based on Bayesian inference with the use of Gaussian Markov random field priors. We construct the priors as a system of stochastic partial differential equations. Numerica

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::3601ed866a5371287c1333c83a734066
https://doi.org/10.1002/2014rs005431

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On the dynamics of large-scale traveling ionospheric disturbances over Europe on 20 November 2003

Autor: Claudia Borries, Daniel Kouba, Olaf Amm, Norbert Jakowski, Kirsti Kauristie, Jens Mielich

Ionospheric disturbances, often associated with geomagnetic storms, may cause threats to radio systems used for communication and navigation. One example is the super storm on 20th November 2003, when plenty of strong and unusual perturbations were r

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c1976d2ca3b80b578b203b129726678a
https://elib.dlr.de/104771/

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Beacon satellite receiver for ionospheric tomography

Autor: Markku Lehtinen, Juha Vierinen, D. McKay-Bukowski, Lassi Roininen, L j Johannes Norberg, Philip J. Erickson, Olaf Amm, Antero Väänänen

Publikováno v: Radio Science. 49:1141-1152

We introduce a new coherent dual-channel beacon satellite receiver intended for ionospheric tomography. The measurement equation includes neutral atmosphere and ionosphere propagation effects, relative errors in satellite and receiver clocks, and res

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::d4d45ca576418f2a29884a82793d7360
https://doi.org/10.1002/2014rs005434

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Development and validation of inversion technique for substorm current wedge using ground magnetic field data

Autor: Robert L. McPherron, Martin Connors, J. Kissinger, Tung-Shin Hsu, Olaf Amm, James Weygand, Zuyin Pu, Vassilis Angelopoulos, Xiangning Chu, Hui Zhang, Krishan K. Khurana

Publikováno v: Journal of Geophysical Research: Space Physics. 119:1909-1924

The classic substorm current wedge model represents ground and space magnetic perturbations measured during substorms. We have developed an inversion technique to calculate parameters determining the intensity and geometry of the current system using

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::ee7045199156d2fb0d6f9b687991228a
https://doi.org/10.1002/2013ja019185

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Illustration of Cowling channel coupling to the shear Alfven wave

Autor: Heikki Vanhamäki, Akimasa Yoshikawa, Ryoichi Fujii, Olaf Amm

Publikováno v: Journal of Geophysical Research: Space Physics. 118:6405-6415

[1] Decomposition of horizontally extended current system into components in the polarization processes and extraction of Cowling channel defined in the companion paper embedded in the total current system are numerically demonstrated. We successfull

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::1b555aedc5c98b32be3de343d8ab79b7
https://doi.org/10.1002/jgra.50513

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