F-Region Storms and Thermospheric Dynamics

Rishbeth, H.

doi:10.5636/jgg.43.supplement1_513

Cited by 97 publications

(90 citation statements)

References 37 publications

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“…Rishbeth, 1991;Prölss, 1995;Field et al, 1998). The calculations show an increase in exospheric temperature T ex (compare to Millstone Hill estimates at 300 km in Fig.…”

Section: Middle Latitudesmentioning

confidence: 56%

“…Thus, an [O] increase due to downwelling motion related to global storm circulation resulting from storm-induced equatorward thermospheric wind can really contribute to the positive NmF2 storm effect, while R(O/N 2 ) ratio remains unchanged. This [O] increase provides a background NmF2 growth (see also Rishbeth, 1991;Field et al, 1998). Additional NmF2 increase is due to enhanced equatortward thermospheric wind (upward plasma drift), resulting from the auroral heating.…”

Section: Lower Latitudesmentioning

confidence: 99%

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An interpretation of the ƒoF2 and hmF2 long-term trends in the framework of the geomagnetic control concept

Mikhailov

Marín

2001

Ann. Geophys.

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Abstract. Earlier revealed morphological features of the foF2 and hmF2 long-term trends are interpreted in the scope of the geomagnetic control concept based on the contemporary F2-layer storm mechanisms. The F2-layer parameter trends strongly depend on the long-term varying geomagnetic activity whose effects cannot be removed from the trends using conventional indices of geomagnetic activity. Therefore, any interpretation of the foF2 and hmF2 trends should consider the geomagnetic effects as an inalienable part of the trend analysis. Periods with negative and positive foF2 and hmF2 trends correspond to the periods of increasing or decreasing geomagnetic activity with the turning points around 1955, and the end of 1960s and 1980s, where foF2 and hmF2 trends change their signs. Such variations can be explained by neutral composition, as well as temperature and thermospheric wind changes related to geomagnetic activity variations. In particular, for the period of increasing geomagnetic activity positive at lower latitudes, but negative at middle and high latitudes, foF2 trends may be explained by neutral composition and temperature changes, while soft electron precipitation determines nighttime trends at sub-auroral and auroral latitudes. A pronounced dependence of the foF2 trends on geomagnetic (invariant) latitude and the absence of any latitudinal dependence for the hmF2 trends are due to different dependencies of NmF2 and hmF2 on main aeronomic parameters. All of the revealed latitudinal and diurnal foF2 and hmF2 trend variations may be explained in the framework of contemporary F2-region storm mechanisms. The newly proposed geomagnetic storm concept used to explain F2-layer parameter long-term trends proceeds from a natural origin of the trends rather than an artificial one, related to the thermosphere cooling due to the greenhouse effect. Within this concept, instead of cooling, one should expect the thermosphere heating for the period of increasing geomagnetic activity .Correspondence to: A. V. Mikhailov (avm71@orc.ru)

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“…Rishbeth, 1991;Prölss, 1995;Field et al, 1998). The calculations show an increase in exospheric temperature T ex (compare to Millstone Hill estimates at 300 km in Fig.…”

Section: Middle Latitudesmentioning

confidence: 56%

Section: Lower Latitudesmentioning

confidence: 99%

An interpretation of the ƒoF2 and hmF2 long-term trends in the framework of the geomagnetic control concept

Mikhailov

Marín

2001

Ann. Geophys.

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“…Therefore, the geomagnetic control concept initially developed for the F2 layer long-term trends A. V. Mikhailov: Ionospheric F1 layer long-term trends and the geomagnetic control concept (Mikhailov, 2002, and references therein) is valid for the F1 layer trends as well. This concept is based on the contemporary theory of the F-layer storms (Rishbeth, 1991;FullerRowell et al, 1994FullerRowell et al, , 1996Prölss, 1995;Rishbeth and Field, 1997;Rishbeth and Müller-Wodarg, 1999). The interaction of the background solar-driven and storm-induced thermospheric circulations is the basic process in this storm mechanism resulting in neutral composition variations.…”

Section: Discussionmentioning

confidence: 99%

Ionospheric F1 layer long-term trends and the geomagnetic control concept

Mikhailov

2008

Ann. Geophys.

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Abstract.A previous approach to the ionospheric long-term trend analysis has been applied to the foF1 observations from Slough and Rome in order to investigate a possible relationship between the foF1 and the long-term variation of geomagnetic activity. A 40-year period, starting in 1962, has been used for the analysis. According to the results obtained earlier for F2 and E-region trends, geomagnetic control of the long-term variation has also been revealed for the foF1. Thus, it is now possible to speak about the geomagnetic control of the ionospheric trends in the whole ionosphere. This is not surprising as the Earth's ionosphere is a single entity that is strongly controlled, either directly or indirectly, by the magnetic field. As with the F2-region, this geomagnetic control is provided via neutral composition and temperature changes. A very long-term (centennial) increase in geomagnetic activity in the 20th century is seen in the long-term foF1 variations as well. After its removal, the residual foF1 trends are very small and insignificant. In principal, this means that the observed foF1 long-term variations have a natural origin and can be attributed to solar and geomagnetic activity longterm variations. However, the situation in the thermosphere has been changing since 1997 and available foF2 observations at the two stations reveal information about the "break down" of the geomagnetic control in the F2-region. Possible reasons of these changes are discussed.

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“…On occasions the enhancement can reach up to almost an order of magnitude [Bruinsma et al, 2006;Liu and Lühr, 2005]. In addition, changes in thermospheric composition occur [e.g., Fuller-Rowell et al, 1991;Rishbeth, 1991;Burns et al, 1995;Field and Rishbeth, 1997], which arise from atmospheric upwelling driven by Joule heating at high latitudes that circulates and redistributes atmospheric constituents globally. These substantial changes take place on time scales that can range from a few hours [e.g., Sutton et al, 2009] to a few days.…”

Section: Introductionmentioning

confidence: 99%

Thermospheric atomic oxygen density estimates using the EISCAT Svalbard Radar

et al. 2013

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[1] Coupling between the ionized and neutral atmosphere through particle collisions allows an indirect study of the neutral atmosphere through measurements of ionospheric plasma parameters. We estimate the neutral density of the upper thermosphere above~250 km with the European Incoherent Scatter Svalbard Radar (ESR) using the year-long operations of the International Polar Year from March 2007 to February 2008. The simplified momentum equation for atomic oxygen ions is used for field-aligned motion in the steady state, taking into account the opposing forces of plasma pressure gradients and gravity only. This restricts the technique to quiet geomagnetic periods, which applies to most of the International Polar Year during the recent very quiet solar minimum. The method works best in the height rangẽ 300-400 km where our assumptions are satisfied. Differences between Mass Spectrometer and Incoherent Scatter and ESR estimates are found to vary with altitude, season, and magnetic disturbance, with the largest discrepancies during the winter months. A total of 9 out of 10 in situ passes by the CHAMP satellite above Svalbard at 350 km altitude agree with the ESR neutral density estimates to within the error bars of the measurements during quiet geomagnetic periods.

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F-Region Storms and Thermospheric Dynamics

Cited by 97 publications

References 37 publications

An interpretation of the <i>ƒo</i>F2 and <i>hm</i>F2 long-term trends in the framework of the geomagnetic control concept

An interpretation of the <i>ƒo</i>F2 and <i>hm</i>F2 long-term trends in the framework of the geomagnetic control concept

Ionospheric F1 layer long-term trends and the geomagnetic control concept

Thermospheric atomic oxygen density estimates using the EISCAT Svalbard Radar

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F-Region Storms and Thermospheric Dynamics

Cited by 97 publications

References 37 publications

An interpretation of the &lt;i&gt;ƒo&lt;/i&gt;F2 and &lt;i&gt;hm&lt;/i&gt;F2 long-term trends in the framework of the geomagnetic control concept

An interpretation of the &lt;i&gt;ƒo&lt;/i&gt;F2 and &lt;i&gt;hm&lt;/i&gt;F2 long-term trends in the framework of the geomagnetic control concept

Ionospheric F1 layer long-term trends and the geomagnetic control concept

Thermospheric atomic oxygen density estimates using the EISCAT Svalbard Radar

Contact Info

Product

Resources

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An interpretation of the <i>ƒo</i>F2 and <i>hm</i>F2 long-term trends in the framework of the geomagnetic control concept

An interpretation of the <i>ƒo</i>F2 and <i>hm</i>F2 long-term trends in the framework of the geomagnetic control concept