arXiv 1203.67152012-03-30astro-ph.SR

第22-24太阳周太阳风的三维演变

Three-dimensional Evolution of Solar Wind during Solar Cycles 22-24

P. K. Manoharan

备注：: 14 pages, 9 figures, Accepted for Publication in The Astrophysical Journal
DOI：: 10.1088/0004-637X/751/2/128

摘要：

本文分析了第22和24太阳活动周期间不同太阳活动水平下太阳风密度、湍流度和速度的三维演变。太阳风的数据是通过Ooty射电望远镜的行星际闪烁测量获得的。结果表明：（1）平均而言，从第22周的最大值到第23周的最小值，密度湍流有下降的趋势;（2）日冕的散射直径从2003年开始逐渐向太阳方向收缩，最深处最小，（3）在第22周和第23周的最小值之间，太阳风速度的纬向分布有显著差异。在太阳活动22周的最低相，当太阳磁场基本上是简单的，接近偶极子的性质时，从两极到30度观测到高速流。两个半球的纬度。相反，在第23周的长衰减阶段，两极的高速风源，根据弱极场，占据了从两极到60度的狭窄纬度带。纬度此外，与日球电流片的大振幅一致，低速风盛行于日球层的低纬度和中纬度地区。(4)在第23和24个周期之间的过渡阶段，在日光层赤道附近观察到高密度和密度湍流，低速风从赤道延伸到中纬度地区。结果与当前周期24的开始一致，从2009年中期开始，它几乎达到了太阳北半球的最大阶段，但南半球的活动尚未发展。

英文摘要：

This paper presents the analysis of 3D evolution of solar wind density turbulence and speed at various levels of solar activity between solar cycles 22 and 24. The solar wind data has been obtained from interplanetary scintillation (IPS) measurements made at the Ooty Radio Telescope. Results show that (i) on the average, there was a downward trend in density turbulence from the maximum of cycle 22 to the deep minimum phase of cycle 23; (2) the scattering diameter of the corona around the Sun shrunk steadily towards the Sun, starting from 2003 to the smallest size at the deepest minimum, and it corresponded to a reduction of ~50% in density turbulence between maximum and minimum phases of cycle 23; (3) The latitudinal distribution of solar wind speed was significantly different between minima of cycles 22 and 23. At the minimum phase of solar cycle 22, when the underlying solar magnetic field was simple and nearly dipole in nature, the high-speed streams were observed from poles to ~30 deg. latitudes in both hemispheres. In contrast, in the long-decay phase of cycle 23, the sources of high-speed wind at both poles, in accordance with the weak polar fields, occupied narrow latitude belts from poles to ~60 deg. latitudes. Moreover, in agreement with the large amplitude of heliospheric current sheet, the low-speed wind prevailed the low- and mid-latitude regions of the heliosphere. (4) At the transition phase between cycles 23 and 24, the high levels of density and density turbulence were observed close to the heliospheric equator and the low-speed speed wind extended from equatorial- to mid-latitude regions. Results are consistent with the onset of the current cycle 24, from middle of 2009 and it has almost reached near to the maximum phase at the northern hemisphere of the Sun, but activity not yet developed in the southern hemisphere.

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