一个基于观测的太阳风背景模型

建立由太阳光球磁场和日冕偏振亮度等观测约束的单流体太阳风模型,包括日冕和太阳风的等离子体密度、速度和磁场,温度还有待于以后处理.这里采用高山观测台(HAO)MKⅢ的日冕偏振亮度(pB)在1.36Rs上的观测概图,根据Guhathakurta在1996年发展的日冕电子密度反演模型确定日冕的电子密度分布.同时采用Wilcox太阳观测台(WSO)的光球磁场视向分量的观测概图作为底部边界,根据Zhao等在1994年发展的水平电流-电流片(HCCS)模型得到全球磁场.Phillips在1995年及McComas在2003年分别用Ulysses第一次和第二次跨极飞行的观测发现,归一化到1 AU的太阳风动量流密度除了在10°～30°的纬度范围内略低以外几乎不变.根据这一结论,结合已经得到的密度数据,就可以得到日冕和太阳风的速度.将上面的模型应用于1918卡林顿自转周稳态太阳风的研究,结果与太阳活动极小期的观测基本相符,但是与观测相比较低速高密度区偏大,因此密度模型还有待改进. 

An Observation-Based Model of Solar Wind Background

Photospheric magnetic field measurements and coronal polarized brightness observations are used as constrains to develop a single-fluid solar wind background model, which includes proton density, bulk velocity and magnetic field. Proton temperature will be dealed with in further studies, The synoptic maps of K-corona polarized Brightness （pB） at 1.36 solar radii observed by MKIII in High Altitude Observator （HAO） are applied to derive corona density according to the solar wind density model constructed by Guhathakurta in 1996. In order to determine the global magnetic field, the synoptic maps of photospheric magnetic field in Wilcox Solar Observatory （WSO） are adopted to be the bottom boundary condition of the model of horizontal current and current sheet （HCCS） established by Zhao in 1994. Researches on observations during Ulysses＇ first and second polar flybyes made by Phillips in 1995 and McComas in 2003 demonstrate that the solar wind momentum flux density scaled to 1 AU is almost invariant except that it is slightly small in the latitude of ±10°-30°, thus the solar wind speed can be derived from this conclusion and the obtained density data. The model is applied to study the solar wind background in Carrington Rotation （CR） 1918 and the results are roughly consistent with the observations in solar minimum. However, the area of high density and slow speed is slightly larger than that observed and thus the density model needs to be further improved.