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Using NSO/Kitt Peak synoptic charts from 1975 to 2003, we group the main solar magnetic fields into two categories: one for
active regions (ARs) and the other for extended bipolar regions (EBRs). Comparing them, we find that there exist three typical
characteristics in the variability of EBRs: First, there exists a correlation between ARs and EBRs. The phase of EBR flux
has a delay nearly two CRs. Second, we find that the EBR flux has two prominent periods at 1.79 years and 3.21 years. The
1.79-year period seems to only belong to large-scale magnetic features. Lastly, the North – South asymmetry of EBR flux is
not very significant on a time scale of one solar cycle. However, during solar maxima, its dominance is found to shift from
one hemisphere to the other. 相似文献
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We study the physical state of the photosphere at about 30 minutes before and at the onset of a 2N/M2 two-ribbon solar flare.
Semiempirical photospheric models are obtained for two Hα-kernels with the help of the SIR inversion code described by Ruiz
Cobo and del Toro Iniesta (Astrophys. J.
398, 375, 1992). The models derived from the inversion reproduce spectral observations in seven Fraunhofer lines. The inferred models show
variations in all photospheric parameters both before and at the onset of the flare relative to the quiet-Sun model. The temperature
enhancement in the upper photospheric layers is found in the atmospheres in both kernels. The dynamical structure in the models
reveals the variations at the onset of the flare relative to the preflaring ones. The inferred atmospheres show some difference
in the thermodynamical parameters of two kernels. 相似文献
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利用Hinode卫星观测的单色像和磁图,对出现在黑子半影内的35对偶极运动磁特征进行形态特征、运动速度以及低层太阳大气响应3方面的研究,得出以下结论:(1)偶极运动磁特征正负两极成对出现在黑子半影较垂直的磁场之间并向着半影外边界运动,间接验证了偶极运动磁特征起源于黑子半影水平磁场,在2-8小时的时间间隔内,同一位置上会反复出现形态特征和运动速度相似的偶极运动磁特征,为海蛇状磁力线模型提供了证据支持. (2)光球和色球在偶极运动磁特征向外运动过程中会出现增亮,说明偶极运动磁特征会加热中低层太阳大气.(3)偶极运动磁特征的出现位置和半影磁场结构分布符合非梳子状黑子半影结构特征. 相似文献
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We have developed an exceptionally noise-resistant method for accurate and automatic identification of supergranular cell
boundaries from velocity measurements. Because of its high noise tolerance the algorithm can produce reliable cell patterns
with only very small amounts of smoothing of the source data in comparison to conventional methods. In this paper we describe
the method and test it with simulated data. We then apply it to the analysis of velocity fields derived from high-resolution
continuum data from MDI (Michelson Doppler Imager) on SOHO. From this, we can identify with high spatial resolution certain
basic properties of supergranulation cells, such as their characteristic sizes, the flow speeds within cells, and their dependence
on cell areas. The effect of the noise and smoothing on the derived cell boundaries is investigated and quantified by using
simulated data. We show in detail the evolution of supergranular cells over their lifetime, including observations of emerging,
splitting, and coalescing cells. A key result of our analysis of cell internal velocities is that there is a simple linear
relation between cell size and cell internal velocity, rather than the power law usually suggested.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
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In a highly dynamic environment with sources and sinks of energy, flux tubes do not in general obey local conservation laws,
nor do the ensembles of flux tubes that exhibit collective phenomena. We use the approach of energetically open dissipative
systems to study nonlinear waves in flux tubes and their role in the dynamics of the overlying atmosphere. We present results
of theoretical and observational studies of the properties of moving magnetic features (MMFs) around sunspots and the response
of the overlying atmosphere to various types of MMFs. We show that all types of MMFs, often having conflicting properties,
can be described on a unified basis by employing the model of shocks and solitons propagating along the penumbral filaments
co-aligned with Evershed flows. The model is also consistent with the response of the upper atmosphere to individual MMFs,
which depends on their type. For example, soliton-type bipolar MMFs mainly participate in the formation of a moat and do not
carry much energy into the upper atmosphere, whereas shock-like MMFs, with the appearance of single-polarity features, are
often associated with chromospheric jets and microflares. 相似文献
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H. P. Jones G. A. Chapman K. L. Harvey J. M. Pap D. G. Preminger M. J. Turmon S. R. Walton 《Solar physics》2008,248(2):323-337
Physical understanding of total and spectral solar irradiance variation depends upon establishing a connection between the
temporal variability of spatially resolved solar structures and spacecraft observations of irradiance. One difficulty in comparing
models derived from different data sets is that the many ways for identifying solar features such as faculae, sunspots, quiet
Sun, and various types of “network” are not necessarily consistent. To learn more about classification differences and how
they affect irradiance models, feature “masks” are compared as derived from five current methods: multidimensional histogram
analysis of NASA/National Solar Observatory/Kitt Peak spectromagnetograph data, statistical pattern recognition applied to
SOHO/Michelson Doppler Imager photograms and magnetograms, threshold masks allowing for influence of spatial surroundings
applied to NSO magnetograms, and “one-trigger” and “three-trigger” algorithms applied to California State University at Northridge
Cartesian Full Disk Telescope intensity observations. In general all of the methods point to the same areas of the Sun for
labeling sunspots and active-region faculae, and available time series of area measurements from the methods correlate well
with each other and with solar irradiance. However, some methods include larger label sets, and there are important differences
in detail, with measurements of sunspot area differing by as much as a factor of two. The methods differ substantially regarding
inclusion of fine spatial scale in the feature definitions. The implications of these differences for modeling solar irradiance
variation are discussed.
K.L. Harvey and S.R. Walton are deseased, to whom this paper is dedicated. 相似文献
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