A comparison of the temperature and density structure in high and low speed thermal proton flows

Raitt, W. J.; Schunk, R. W.; Banks, Peter M.

doi:10.1016/0032-0633(75)90200-7

Cited by 135 publications

(73 citation statements)

References 16 publications

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“…For boundary conditions the ion densities, we equated local production and loss rates at the lower boundary (140 km) and we assumed no flux of ions across our upper boundary (800 km). Earlier studies by Raitt et al [1975] have indicated that a polar wind outflow has a negligible effect on the 0 + density profile at altitudes below 800 km. The complete details concerning the combined plasma convection and ionosphericatmospheric models are given by Sojka et aL [1981a] and are not repeated here.…”

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confidence: 91%

Plasma density features associated with strong convection in the winter high‐latitude F region

Sojka¹,

Raitt²,

Schunk³

1981

J. Geophys. Res.

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We combined a simple plasma convection model with an ionospheric-atmospheric composition model in order to study the plasma density features associated with strong convection in the winter high-latitude F region. Our numerical study produced time-dependent, three-dimensional, ion density distributions for the ions NO +, O 2 +, N2 + , 0 + , N +, and He +. We covered the highlatitude ionosphere above 42° N magnetic latitude and at altitudes between 160 and 800 km for a time period of one complete day. From our study, we found the following: (1) For strong convection, the electron density exhibits a significant variation with altitude, latitude, longitude, and universal time. A similar result was obtained in our previous study dealing with a weak convection model. (2) For strong convection, ionospheric features, such as the main trough, the aurorally produced ionization peaks, the polar hole, and the tongue of ionization, are evident but they are modified in comparison with those found for slow convection. (3) For strong convection, the tongue of ionization is much more pronounced than for weak convection. (4) The polar hole that is associated with quiet geomagnetic activity conditions does not form when the plasma convection is strong. (5) For strong convection, a new polar hole appears in the polar cap at certain universal times. This new polar hole is associated with large downward, electrodynamic plasma drifts. (6) For strong convection, the main or mid-latitude electron density trough is not as deep as that found for a weak convection model. However, it is still strongly UT dependent. (7) The ionospheric parameters N mF2' hmFt, and the topside plasma density scale height exhibit an appreciable variation over the polar region at a given UT.

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confidence: 91%

Plasma density features associated with strong convection in the winter high‐latitude F region

Sojka¹,

Raitt²,

Schunk³

1981

J. Geophys. Res.

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“…For boundary conditions on the ion densities, we equated local production and loss rates at the lower boundary (140 km) and we assumed no flux of ions across our upper boundary (800 km). Earlier studies by Raitt et al [1975] have indicated that a polar wind oU~flow has a negligible effect on the 0+ density profile at altItudes below 800 km. The complete details concerning the combined plasma convection and ionosphericatmospheric models are given by Sojka et aL [1981a] and are not repeated here.…”

mentioning

confidence: 91%

Seasonal variations of the high‐latitude F region for strong convection

Sojka

Schunk²,

Raitt

1982

J. Geophys. Res.

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We combined a plasma convection model with an ionospheric-atmospheric composition model in order to study the seasonal variations of the high-latitude F region for strong convection. Our numerical study produced time-dependent, three-dimensional, ion density distributions for the ions NO+, 0/, N/, 0+, N+, and He+. We covered the high-latitude ionosphere above 42°N magnetic latitude and at altitudes between 160 and 800 km for a time period of one complete day. From our study we found the following: (1) For strong convection, the high-latitude ionosphere exhibits a significant UT variation both during winter and summer. (2) In general, the electron density is lower in winter than in summer. However, at certain universal times the electron density in the dayside polar cap is larger in winter than in summer owing to the effect of the midlatitude 'winter anomaly' in combination with strong antisunward convection. (3) In both summer and winter, the major region of low electron density is associated with the main or midlatitude trough. The trough is deeper and its local time extent is much greater in winter than in summer. (4) Typically, the electron density exhibits a much larger variation with altitude in winter than in summer. (5) The ion composition and molecular/atomic ion transition altitude are highly UT dependent in both summer and winter. (6) The ion composition also displays a significant seasonal variation. However, at a given location the seasonal variation can be opposite at different universal times. (7) High-speed convection cells should display a marked seasonal variation, with a much larger concentration of molecular ions near the F region peak in summer than in winter.

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“…A number of models of the polar wind have been proposed; hydrodynamic models Holzer, 1968, 1969a, b;Marubashi, 1970;Raitt et al, 1975Raitt et al, , 1977Schunk et al, 1978), kinetic models Scherer, 1970, 1973), models solving the generalized transport equations Watkins, 1981, 1982;Demars and Schunk, 1987;Ganguli et al, 1987) and time-dependent models (Gombosi and Nagy, 1989;Schunk and Sojka, 1989). Polar wind observations are dated from the early years of the 1970s with the Explorer 31, OGO 2, and ISIS 2 satellites (Homan, 1970;Taylor and Walsh, 1972;Homan et al, 1974) and in the 1980s case studies of the polar wind were carried out based on data obtained from the Dynamic Explorer (DE) 1 satellite (Shelley et al, 1982;Nagai et al, 1984;Chandler et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Ion upflow and downflow at the topside ionosphere observed by the EISCAT VHF radar

et al. 2000

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Abstract. We have determined the MLT distribution and K P dependence of the ion up¯ow and down¯ow of the thermal bulk oxygen ion population based on a data analysis using the EISCAT VHF radar CP-7 data obtained at Tromsù during the period between 1990 and 1996: (1) both ion up¯ow and down¯ow events can be observed at any local time (MLT), irrespective of dayside and nightside, and under any magnetic disturbance level, irrespective of quiet and disturbed levels; (2) these up¯ow and down¯ow events are more frequently observed in the nightside than in the dayside; (3) the up¯ow events are more frequently observed than the down¯ow events at any local time except midnight and at any K P level and the dierence of the occurrence frequencies between the up¯ow and down¯ow events is smaller around midnight; and (4) the occurrence frequencies of both the ion up¯ow and down¯ow events appear to increase with increasing K P level, while the occurrence frequency of the down¯ow appears to stop increasing at some K P level.

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A comparison of the temperature and density structure in high and low speed thermal proton flows

Cited by 135 publications

References 16 publications

Plasma density features associated with strong convection in the winter high‐latitude F region

Plasma density features associated with strong convection in the winter high‐latitude F region

Seasonal variations of the high‐latitude F region for strong convection

Ion upflow and downflow at the topside ionosphere observed by the EISCAT VHF radar

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