Correlation of plasma scale height withKpin the topside ionosphere

Watt, T. M.

doi:10.1029/jz071i013p03131

Cited by 10 publications

(9 citation statements)

References 10 publications

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“…In the study of midlatitude and high-latitude Alouette i soundings described in earlier publications [Watt, 1965[Watt, , 1966, we found that typical day and typical night observations be- where. Observed electron density distributions below about 450 km altitude could not be explained in terms of diffusive equilibrium, and we judged that production and loss processes were probably dominant below that altitude.…”

Section: Ac(a) ---V(a) /(O V/o A)supporting

confidence: 48%

Topside ionosphere at sunrise

Watt¹

1971

J. Geophys. Res.

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The sunrise behavior of the midlatitude topside ionosphere at low sunspot numbers was examined by using Alouette I electron density and plasma scale height profiles obtained at Stanford University during May and June 1963. Under the assumption that observed variations result from solar control, the data were averaged to form height profiles of plasma scale height and electron density from 450 to 750, km altitude, which vary smoothly with solar zenith angle x. The first manifestation of sunrise is a sudden and rapid decrease in plasma scale height, beginning between •: • 105 ø and 102 ø and ending between •: • 98 ø and 96 ø. Electron densities increase rapidly between x • 98 ø and 95 ø. Our interpretation of the observations is that the sudden decrease in plasma scale heights is due to an increase in percentage concentration of O f ions at all altitudes, due primarily to a thermal expansion of the ionosphere that causes an upward movement of the topside ionization. The velocity of the thermal motion is estimated, and we attempt to resolve conflicting evidence from other observations that the topside ionosphere is controlled by either geomagnetic latitude or solar zenith angle.

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Section: Ac(a) ---V(a) /(O V/o A)supporting

confidence: 48%

Topside ionosphere at sunrise

Watt¹

1971

J. Geophys. Res.

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“…The similarity lies in the highest altitudes where both model and observations have Hp ranging from 300 to 400 km, while for the quiet pass, the range of Hp is smaller, around Hp = 300 km. Watt (1965Watt ( , 1966 carried out topside scale height analysis of Alouette-1 topside ionograms. He showed that poleward of 62°dip latitude, the transition height between O + and the light ions (H + and He + ) was above 900 km (see Figure 9 of Watt, 1965).…”

Section: Radio Sciencementioning

confidence: 99%

“…Reports on how the temperature, electrons, or ions responded to geomagnetic storms at high latitudes were somewhat mixed. Willmore () and Titheridge and Andrews () reported cooling, while Watt () and Nishida () reported heating.…”

Section: Introductionmentioning

confidence: 99%

Polar Topside Ionosphere During Geomagnetic Storms: Comparison of ISIS‐II With TDIM

et al. 2018

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Space weather deposits energy into the high polar latitudes, primarily via Joule heating that is associated with the Poynting flux electromagnetic energy flow between the magnetosphere and ionosphere. One way to observe this energy flow is to look at the ionospheric electron density profile (EDP), especially that of the topside. The altitude location of the ionospheric peak provides additional information on the net field-aligned vertical transport at high latitudes. To date, there have been few studies in which physics-based ionospheric model storm simulations have been compared with topside EDPs. A rich database of high-latitude topside ionograms obtained from polar orbiting satellites of the International Satellites for Ionospheric Studies (ISIS) program exists but has not been utilized in comparisons with physics-based models. Of specific importance is that the Alouette/ISIS topside EDPs spanned the timeframe from 1962 to 1983, a period that experienced very large geomagnetic storms. We use a physics-based ionospheric model, the Utah State University Time Dependent Ionospheric Model (TDIM), to simulate ionospheric EDPs for quiet and storm high-latitude passes of ISIS-II for two geomagnetic storms. This initial study finds that under quiet conditions there is good agreement between model and observations. During disturbed conditions, however, a large difference is seen between model and observations. The model limitation is probably associated with the inability of its topside boundary to replicate strong outflow conditions. As a result, modeling of the ionospheric outflows needs to be extended well into the magnetosphere, thereby moving the upper boundary much higher and requiring the use of polar wind models.The special issue of the monthly Proceedings of Institute of Electrical and Electronics Engineers (IEEE) in June 1969 provided an extensive overview of a technique for observing the topside ionosphere, the satellite-borne topside sounder (Institute of Electrical and Electronics Engineers, 1969). Chan and Colin (1969) reviewed and summarized the global electron density distributions from topside soundings, while Warren (1969) reviewed the topside ionospheric response to geomagnetic storms. A brief report by Norton (1969) in this particular issue of proceedings of IEEE proposed that in order to explain the midlatitude morning springtime topside SOJKA ET AL. 906Key Points:• The paper focuses on prestorm and main phase topside ionospheric response to a mild and a severe geomagnetic storm • Simulations from an extensively used F region model, TDIM, are compared to ISIS-II topside ionosphere observations • Surprisingly, the TDIM is unable to simulate the observed storm response while satisfactorily simulating the prestorm topsideCorrespondence to:

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“…Using the same Thomson scatter facility, P. B. Rao [1968] observed that during the storm of June 15-16, 1965, the electron temperature at night was 200-300K higher than normal but could find no temperature difference at daytime, although the electron concentration then seemed to be enhanced by a factor of from 1.5-2.0. Indication that the nighttime plasma temperature depends on the degree of geomagnetic activity was found by Watt [1966] who, from plasma scale heights observed with Alouette 1, concluded that the particle temperature in the F region increased about 4% for each unit increase in K Extensive investigation for hydromagnetic and ionacoustic waves [Poeverlein, 1967[Poeverlein, , 1968 An experiment to relate the primary precipitating auroral particles to radio auroral echoes was carried out by Leadabrand and Hodges [1967]. A VHF and UHF radar with a pencil beam was used in conjunction with a polar orbit satellite containing appropriate proton and electron particle detectors.…”

Section: Ionospheric Radio Commission 3 607mentioning

confidence: 99%

Commission 3: Progress in Ionospheric Radio

Villard¹,

Aarons²,

Bibl³

et al. 1969

Radio Science

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The major advances in our understanding of the morphology of the D region in the last three years have come about through the application of rocket techniques. A series of rocket measurements carried out at Wallops Island [Mechtly and Smith, 1968a] at different seasons but at roughly the same solar zenith angle have shown the principal features of the seasonal variation in the electron density profile between 50 and 100 km. It appears that electron densities are lower by a factor of about 3 below 82 km on ‘normal’ winter days as compared with summer days for a solar zenith angle of 60°. The anomalous winter days of high absorption have been the subject of a separate rocket investigation [Sechrist et al., 1969], which has shown that the electron density profile is remarkably similar to that of a normal summer day and that in at least one case was associated with a pronounced temperature inversion near 70 km.

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Correlation of plasma scale height withK_pin the topside ionosphere

Cited by 10 publications

References 10 publications

Topside ionosphere at sunrise

Topside ionosphere at sunrise

Polar Topside Ionosphere During Geomagnetic Storms: Comparison of ISIS‐II With TDIM

Commission 3: Progress in Ionospheric Radio

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