Zobrazeno 1 - 10
of 87
pro vyhledávání: '"H. Lundstedt"'
Publikováno v:
Annales Geophysicae, Vol 33, Pp 109-116 (2015)
A complex solid torus model was developed in order to be able to study an extreme solar storm, the so-called "Great Storm" or "New York Railroad Storm" of May 1921, when neither high spatial and time resolution magnetic field measurements, sola
Externí odkaz:
https://doaj.org/article/31981b44651a4d5c89c94b465cda94a6
Autor:
H. Lundstedt, T. Persson
Publikováno v:
Annales Geophysicae, Vol 28, Pp 993-1002 (2010)
Two systems of Lorenz-type equations modelling solar magnetic activity are studied: Firstly a low order dynamic system in which the toroidal and poloidal fields are represented by x- and y-coordinates respectively, and the hydrodynamical informati
Externí odkaz:
https://doaj.org/article/5a1d0de55ea44463b67c14cfc923db3e
Publikováno v:
Annales Geophysicae, Vol 27, Pp 1775-1787 (2009)
In this paper, we analyse in detail two famous space weather events; a railway problem on 13–14 July 1982 and a power blackout on 30 October 2003. Both occurred in Sweden during very intensive space weather storms and each of them a few years af
Externí odkaz:
https://doaj.org/article/12990e59eb7840feac24b3823b33fb0e
Publikováno v:
Annales Geophysicae, Vol 24, Pp 769-778 (2006)
Long-term solar activity has been studied with a set of wavelet methods. The following indicators of long-term solar activity were used; the group sunspot number, the sunspot number, and the 14C production rate. Scalograms showed the very long-ter
Externí odkaz:
https://doaj.org/article/7a27f34a62f346c3b437f45e60334a3c
Publikováno v:
Annales Geophysicae, Vol 23, Pp 3095-3101 (2005)
The 7-10 November 2004 period contains two events for which the local ground magnetic field was severely disturbed and simultaneously, the solar wind displayed several shocks and negative Bz periods. Using empirical models the 10-min RMS and at Br
Externí odkaz:
https://doaj.org/article/0d39773581134a69aea21384a1acd505
Publikováno v:
Annales Geophysicae, Vol 23, Pp 1505-1511 (2005)
In order to improve the forecasts of the impact of solar activity on the terrestrial environment on time scales longer than days, improved understanding and forecasts of the solar activity are needed. The first results of a new approach of modelli
Externí odkaz:
https://doaj.org/article/23b6cf96211445a1bb59f5822f44ba78
Autor:
H. Gleisner, H. Lundstedt
Publikováno v:
Annales Geophysicae, Vol 17, Pp 1268-1275 (1999)
Geomagnetic storms and substorms develop under strong control of the solar wind. This is demonstrated by the fact that the geomagnetic activity indices Dst and AE can be predicted from the solar wind alone. A consequence of the strong control by a
Externí odkaz:
https://doaj.org/article/c9344bfc648d4ba48765e8c19f611cac
Publikováno v:
Annales Geophysicae, Vol 14, Pp 679-686 (1996)
We have used time-delay feed-forward neural networks to compute the geomagnetic-activity index Dst one hour ahead from a temporal sequence of solar-wind data. The input data include solar-wind density n, velocity V and the southward component Bz
Externí odkaz:
https://doaj.org/article/3f7a97895a734575a48fa1d102e90d1f
Autor:
H. Lundstedt, P. Wintoft
Publikováno v:
Annales Geophysicae, Vol 12, Pp 19-24 (1994)
An artificial feed-forward neural network with one hidden layer and error back-propagation learning is used to predict the geomagnetic activity index (Dst) one hour in advance. The Bz-component and ΣBz, the density, and the velocity of the solar
Externí odkaz:
https://doaj.org/article/6ea9944058c94e9592a94b9a0bc43d48
Autor:
H. Lundstedt, P. Wintoft
Publikováno v:
Annales Geophysicae, Vol 12, Iss 1, Pp 19-24 (0000)
An artificial feed-forward neural network with one hidden layer and error back-propagation learning is used to predict the geomagnetic activity index (Dst) one hour in advance. The Bz-component and ΣBz, the density, and the velocity of the solar win
Externí odkaz:
https://doaj.org/article/011613928bed4300b8e7fd6872bc44f9