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Solar wind speed structure in the inner corona at 3–12 R o
Author(s) -
Woo Richard
Publication year - 1995
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/95gl01315
Subject(s) - physics , interplanetary scintillation , wind speed , longitude , solar radius , solar wind , latitude , corona (planetary geology) , astrophysics , heliosphere , atmospheric sciences , meteorology , coronal mass ejection , astronomy , plasma , quantum mechanics , astrobiology , venus
Estimates of solar wind speed obtained by Armstrong et al. [1986] based on 1983 VLA multiple‐station intensity scintillation measurements inside 12 R o have been correlated with the electron density structure observed in white‐light coronagraph measurements. The observed large‐scale and apparently systematic speed variations are found to depend primarily on changes in heliographic latitude and longitude, which leads to the first results on large‐scale speed structure in the acceleration region of the solar wind. Over an equatorial hole, solar wind speed is relatively steady, with peak‐to‐peak variations of 50 km/s and an average of 230 km/s. In contrast, the near‐Sun flow speed across the streamer belt shows regular large‐scale variations in the range of 100–300 km/s. Based on four groups of data, the gradient is 36 km/s per degree in heliocentric coordinates (corresponding to a rise of 260 km/s over a spatial distance on the Sun of two arcmin) with a standard deviation of 2.4 km/s per degree. The lowest speeds most likely coincide with the stalks of coronal streamers observed in white‐light measurements. The detection of significant wind shear over the streamer belt is consistent with in situ and scintillation measurements showing that the density spectrum has a power‐law form characteristic of fully developed turbulence over a much broader range of scales than in neighboring regions.