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Detailed Reference Information |
Coles, W.A., Grall, R.R., Klinglesmith, M.T. and Bourgois, G. (1995). Solar cycle changes in the level of compressive microturbulence near the Sun. Journal of Geophysical Research 100: doi: 10.1029/95JA00896. issn: 0148-0227. |
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Observations of the coherence bandwidth of interplanetary scintillations (IPS) made at the Nan¿ay Radio Observatory between 1982 and 1992 have been used to estimate the variance of electron density ΔN2e at solar distances of 5 to 15 Rs. These IPS observations are sensitive to scales of the order of 10 km; i.e., they measure the ''microscale variance,'' which is a small fraction of the total density variance. Measurements in the equatorial region are invariant over the solar activity cycle and show the same behavior with distance as the mean density, i.e., ΔN2e∝N2e. They do not show a statistically significant change in the ''transonic region'' as reported by other observers (Lotova et al., 1985). Measurements over the polar region show a clear variation with the solar cycle. At solar maximum, ΔN2e is invariant with latitude, as is Ne (Withbroe, 1988). However, the apparent ΔN2e measured by IPS is about 10 times lower in the polar streams which form during the declining and minimum phases of solar activity. Compensation for the line of sight integration inherent in the IPS observations indicates that the local value of ΔN2e is actually about 15 times lower in the polar streams. We cannot estimate the latitude variation of the ''development'' of the compressive turbulence ΔNe/Ne between 5 and 15 Rs because measurements of Ne in the polar hole are lacking. ¿ American Geophysical Union 1995 |
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Abstract |
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Keywords
Interplanetary Physics, Solar wind plasma, Interplanetary Physics, Plasma waves and turbulence, Interplanetary Physics, Solar cycle variations, Solar Physics, Astrophysics, and Astronomy, Corona |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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