Výsledky vyhledávání - "J. K. Hargreaves"

Akademický článek

On the fine structure of medium energy electron fluxes in the auroral zone and related effects in the ionospheric D-region

Autor: J. K. Hargreaves, M. J. Birch, D. S. Evans

Publikováno v: Annales Geophysicae, Vol 28, Pp 1107-1120 (2010)

This study is based on measurements of trapped and precipitated electrons of energy >30 keV and >100 keV observed by polar orbiting environmental satellites during overpasses of the imaging riometer at Kilpisjärvi, Finland. The satellites are in s

Externí odkaz: https://doaj.org/article/17dc3085e4104cb0bfd9b309f671281d

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Akademický článek

D- and E-region effects in the auroral zone during a moderately active 24-h period in July 2005

Autor: J. K. Hargreaves, M. J. Birch, B. J. I. Bromage

Publikováno v: Annales Geophysicae, Vol 25, Pp 1837-1849 (2007)

The effects of energetic electron precipitation into the auroral region at a time of enhanced solar wind have been investigated during a continuous period of 24 h, using the European Incoherent Scatter (EISCAT) radar, an imaging riometer, and part

Externí odkaz: https://doaj.org/article/06419d0f36b04dcb960ef3c656125a4b

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Akademický článek

Seasonal variations in the incidence of auroral radio absorption events at very high latitude, and the influence of the magnetotail

Autor: J. K. Hargreaves

Publikováno v: Annales Geophysicae, Vol 25, Pp 711-720 (2007)

A statistical analysis has been made of the incidence of auroral radio absorption events at South Pole, and of its dependence on basic geophysical parameters such as season, time of day, and magnetic activity level. It is found that at low and mod

Externí odkaz: https://doaj.org/article/2b4fe601c800403c90d070d2bf0afd78

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Akademický článek

On the relations between proton influx and D-region electron densities during the polar-cap absorption event of 28-29 October 2003

Autor: J. K. Hargreaves, M. J. Birch

Publikováno v: Annales Geophysicae, Vol 23, Pp 3267-3276 (2005)

Observations by incoherent-scatter radar have been applied to explore relationships between the fluxes of incident protons and the resulting D-region electron densities during a polar-cap radio-absorption event. Using proton flux data from a GOES

Externí odkaz: https://doaj.org/article/c3248a86f10e4b279376e0353a002318

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Akademický článek

A new method of studying the relation between ionization rates and radio-wave absorption in polar-cap absorption events

Autor: J. K. Hargreaves

Publikováno v: Annales Geophysicae, Vol 23, Pp 359-369 (2005)

During polar-cap absorption events, which are caused by the incidence of energetic solar protons, the high-latitude ionospheric D region is extended down to relatively low altitudes. While the incoming proton fluxes may be monitored by satellite-b

Externí odkaz: https://doaj.org/article/dac600cd7de848d09ce20454363c8f38

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Akademický článek

The estimation of D-region electron densities from riometer data

Autor: J. K. Hargreaves, M. Friedrich

Publikováno v: Annales Geophysicae, Vol 21, Pp 603-613 (2003)

At high latitude the hard electron precipitation associated with auroral activity is a major source of ionization for the D-region, one consequence being the absorption of radio waves. Direct measurements of the D-region electron density are no

Externí odkaz: https://doaj.org/article/d5cce946006d4134a07a81a5e1def90a

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Akademický článek

A localised co-rotating auroral absorption event observed near noon using imaging riometer and EISCAT

Autor: P. N. Collis, J. K. Hargreaves, G. P. White

Publikováno v: Annales Geophysicae, Vol 14, Pp 1305-1316 (1996)

An isolated region of energetic electron precipitation observed near local noon in the auroral zone has been investigated using imaging riometer (IRIS) and incoherent-scatter radar (EISCAT) techniques. IRIS revealed that the absorption event was e

Externí odkaz: https://doaj.org/article/a31a873a43494d24b5b103441970f2a6

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Elektronická kniha

The High-Latitude Ionosphere and Its Effects on Radio Propagation

Autor: R. D. Hunsucker, J. K. Hargreaves

The physical properties of the ionized layer in the Earth's upper atmosphere enable us to use it to support an increasing range of communications applications. This book presents a modern treatment of the physics and phenomena of the high latitude up

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Seasonal variations in the incidence of auroral radio absorption events at very high latitude, and the influence of the magnetotail

Autor: J. K. Hargreaves

Publikováno v: Annales Geophysicae, Vol 25, Pp 711-720 (2007)
Annales Geophysicae
Annales Geophysicae, European Geosciences Union, 2007, 25 (3), pp.711-720
Annales Geophysicae, Vol 25, Iss 3, Pp 711-720 (2007)

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::58db730012c28bd2ed4bb037c6b72c2a
https://www.ann-geophys.net/25/711/2007/

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Variations in cutoff latitude during selected solar energetic proton events

Autor: B. J. I. Bromage, Martin John Birch, J. K. Hargreaves, Andrew Senior

Publikováno v: Journal of Geophysical Research. 110

Proton count rate measurements were obtained from the polar orbiting environmental satellites POES15 and POES16 during three solar proton events in 2001. From these data the invariant latitude of the cutoff in proton flux was determined at four local

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::42337c562cf4bc7042198454c74cf78d
https://doi.org/10.1029/2004ja010833

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