Geomagnetic and solar control of ionization at 1000 km

Chandra, S.; Rangaswamy, S.

doi:10.1016/0021-9169(67)90195-x

Cited by 12 publications

(10 citation statements)

References 5 publications

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“…The abundances of these ions are dominated by transport and chemical processes (e.g. Chandra and Rangaswamy, 1967;West et al, 1997;Zhao et al, 2005). The plasma distribution of the equatorial and midlatitude ionosphere is subject to a number of transport processes involving thermospheric neutral winds, E×B drifts, and field-aligned diffusions (Venkatraman and Heelis, 2000).…”

Section: Discussionmentioning

confidence: 99%

The dependence of plasma density in the topside ionosphere on the solar activity level

et al. 2007

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Abstract. In this paper, the ten-year (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) total ion density N i measurements from the Defense Meteorological Satellite Program (DMSP) spacecraft in the morning and evening (09:30 and 21:30 LT) sectors have been analyzed to explore the dependence of plasma densities in the topside ionosphere at middle and low latitudes on the solar activity level. Results indicate that there is a strong solar activity dependence of DMSP N i at 848 km altitude, which has latitudinal and seasonal features. The plasma density in the topside ionosphere has an approximately linear dependence on daily F107 and a strongly nonlinear dependence on SEM/SOHO EUV, such that the change rate of N i becomes greater with increasing solar EUV. This is quite different from the dependence of N i near the F-Region peak (NmF2), at which the rate of change of NmF2 decreases with increasing solar EUV. The rate of change of N i at the DMSP altitude is greatest in the latitude range where N i is greatest during high solar activity. We suggest that this greater rate of change (or amplification effect) of N i at the DMSP altitude is mainly a consequence of the solar activity variations of the topside scale height. The changes in the height of the F-Region peak (hmF 2 ) and the density NmF2 play a secondary role.

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Section: Discussionmentioning

confidence: 99%

The dependence of plasma density in the topside ionosphere on the solar activity level

et al. 2007

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“…Brace et al, , 1968Reddy et al, 1967). The configuration is mainly affected by geomagnetism and solar control (Chandra and Rangaswamy, 1967). In the topside ionosphere, except for the downward flux from the protonosphere, H + is mainly obtained through the charge exchange between O + and hydrogen; O + and He + are produced by photoionization, and their production rate is proportional to the cosine of the solar zenith angle cosχ .…”

Section: Empirical Orthogonal Functions Analysismentioning

confidence: 99%

Statistical characteristics of the total ion density in the topside ionosphere during the period 1996-2004 using empirical orthogonal function (EOF) analysis

et al. 2005

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Abstract.We have applied the empirical orthogonal function (EOF) analysis to examine the climatology of the total ion density Ni at 840 km during the period 1996-2004, obtained from the Defense Meteorological Satellite Program (DMSP) spacecraft. The data set for each of the local time (09:30 LT and 21:30 LT) is decomposed into a time mean plus the sum of EOF bases E i of space, multiplied by time-varying EOF coefficients A i . Physical explanations are made on the first three EOFs, which together can capture more than 95% of the total variance of the original data set. Results show that the dominant mode that controls the N i variability is the solar EUV flux, which is consistent with the results of Rich et al. (2003). The second EOF, associated with the solar declination, presents an annual (summer to winter) asymmetry that is caused by the transequatorial winds. The semiannual variation that appears in the third EOF for the evening sector is interpreted as both the effects of the equatorial electric fields and the wind patterns. Both the annual and semiannual variations are modulated by the solar flux, which has a close relationship with the O + composition. The quick convergence of the EOF expansion makes it very convenient to construct an empirical model for the original data set. The modeled results show that the accuracy of the prediction depends mainly on the first principal component which has a close relationship with the solar EUV flux.

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“…A study of topside sounder data by Chandra and Rangaswamy [1967] showed that explained on the basis of the latitudinal variation in the magnetic dip angle and the solar zenith angle. While this conclusion appears to be closely associated with the present results, the previous study did not include any information on the topside ion composition.…”

mentioning

confidence: 99%

Evidence of solar geomagnetic seasonal control of the topside ionosphere

Taylor

1971

Planetary and Space Science

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Geomagnetic and solar control of ionization at 1000 km

Cited by 12 publications

References 5 publications

The dependence of plasma density in the topside ionosphere on the solar activity level

The dependence of plasma density in the topside ionosphere on the solar activity level

Statistical characteristics of the total ion density in the topside ionosphere during the period 1996-2004 using empirical orthogonal function (EOF) analysis

Evidence of solar geomagnetic seasonal control of the topside ionosphere

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