Výsledky vyhledávání - "Tuomo Nygrén"

IMF effect on sporadic-E layers at two northern polar cap sites: Part II – Electric field

Autor: J. M. Ruohoniemi, Anita Aikio, Tuomo Nygrén, Mirela Voiculescu

Publikováno v: Annales Geophysicae, Vol 24, Pp 901-913 (2006)
Annales Geophysicae, Vol 24, Iss 3, Pp 901-913 (2006)

This paper is the second in a series on a study of the link between IMF and sporadic-E layers within the polar cap. In Paper I (Voiculescu et al., 2006), an analysis of the sporadic-E data from Thule and Longyearbyen was presented. Here we concentrat

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::d5c9121b1792b6d8cdfde57778bc009e
https://www.ann-geophys.net/24/901/2006/

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Anisotropy of ionospheric irregularities determined from the amplitude of satellite signals at a single receiver

Autor: Tuomo Nygrén, E. D. Tereshchenko, M. O. Kozlova, B. Z. Khudukon

Publikováno v: Scopus-Elsevier
Annales Geophysicae, Vol 17, Pp 508-518 (1999)
Annales Geophysicae
Annales Geophysicae, European Geosciences Union, 1999, 17 (4), pp.508-518
Annales Geophysicae, Vol 17, Iss 4, Pp 508-518 (0000)

A new method of determining the anisotropy parameters of small-scale irregularities in the ionospheric F region is presented and experimental results are shown. The method is based on observations of amplitude fluctuations of radio waves transmitted

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::dd90b5993eeb8989eac054a2355728ac
https://www.ann-geophys.net/17/508/1999/

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Calculation of signal spectrum by means of stochastic inversion

Autor: Th. Ulich, Tuomo Nygrén

Publikováno v: Annales Geophysicae, Vol 28, Pp 1409-1418 (2010)

The standard method of calculating the spectrum of a digital signal is based on the Fourier transform, which gives the amplitude and phase spectra at a set of equidistant frequencies from signal samples taken at equal intervals. In this paper a diffe

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::19051fecc3036b453af6a138dca7d331
https://www.ann-geophys.net/28/1409/2010/

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High-precision measurement of satellite range and velocity using the EISCAT radar

Autor: Tuomo Nygrén, M. Markkanen, J. Markkanen, Anita Aikio, Mirela Voiculescu

Publikováno v: Annales Geophysicae, Vol 31, Pp 859-870 (2013)

This paper is a continuation of an earlier work by Nygrén et al. (2012), where the velocity of a hard target was determined from a set of echo pulses reflected by the target flying through the radar beam. Here the method is extended to include the d

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::bec2141a428bfa22bcd269623eb99db0
https://www.ann-geophys.net/31/859/2013/

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Lag profile inversion method for EISCAT data analysis

Autor: Tuomo Nygrén, Markku Lehtinen, Ilkka Virtanen, Juha Vierinen, Mikko Orispää

Publikováno v: Annales Geophysicae, Vol 26, Iss 3, Pp 571-581 (2008)
Annales Geophysicae, Vol 26, Pp 571-581 (2008)
Scopus-Elsevier
Mikko Orispää
ResearcherID

The present standard EISCAT incoherent scatter experiments are based on alternating codes that are decoded in power domain by simple summation and subtraction operations. The signal is first digitised and then different lagged products are calculated

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::acb9e7115af4b34e2548b282797968d5
https://www.ann-geophys.net/26/571/2008/

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Radar observations of simultaneous traveling ionospheric disturbances and atmospheric gravity waves

Autor: Anita Aikio, Lei Cai, Mirela Voiculescu, Tuomo Nygrén

Publikováno v: Journal of Geophysical Research: Space Physics. 120:3949-3960

Simultaneous observations of atmospheric gravity waves (AGWs) and traveling ionospheric disturbances (TIDs) measured by an incoherent scatter radar at high latitudes are shown. The measurements were made using a beam swing experiment of the EISCAT UH

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::ee555af906779585e594a275ae88c754
https://doi.org/10.1002/2014ja020794

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Height-dependent energy exchange rates in the high-latitudeEregion ionosphere

Autor: Tuomo Nygrén, Anita Aikio, Lei Cai

Publikováno v: Journal of Geophysical Research: Space Physics. 118:7369-7383

[1] The statistical properties of the altitude profiles of the different energy transfer rates in the auroral ionosphere are studied by using the European Incoherent Scatter radar measurements in Tromso (67° cgmLat). Aikio et al. (2012) found that d

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::a29c0d75734e4b7c233bf5e3d4511d94
https://doi.org/10.1002/2013ja019195

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High-precision measurement of satellite velocity using the EISCAT radar

Autor: Anita Aikio, Mirela Voiculescu, J. Markkanen, Tuomo Nygrén

Publikováno v: Annales Geophysicae, Vol 30, Pp 1555-1565 (2012)

This paper presents a method of measuring the velocity of a hard target using radar pulses reflected from the target flying through the radar beam. The method has two stages. First, the Doppler shifts of the echo pulses are calculated at a high accur

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7464a1a4ccfa5d4aec67c03d5a637f00
https://www.ann-geophys.net/30/1555/2012/angeo-30-1555-2012.pdf

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Postmidnight ionospheric troughs in summer at high latitudes

Autor: Heikki Vanhamäki, Mirela Voiculescu, Anita Aikio, Viviane Pierrard, Tuomo Nygrén

Publikováno v: Journal of Geophysical Research: Space Physics. 121:12-12,185

In this article we identify possible mechanisms for the formation of post-midnignt ionospheric troughs during summer, in sunlit plasma. Four events were identified in measurements of EISCAT and ESR radars during CP3 experiments, when the ionosphere w

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::d5267527a4c9217c703873bceefa9278
https://doi.org/10.1002/2016ja023360

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