Contribution Function And Three-Dimensional Reconstruction Of Hα Chromospheric Flare

Since the first solar image was transmitted back to the ground by space telescopes such as SOHO, YOHKOH, people have been more familiar with many kinds of three-dimensional structure of the active phenomena in solar atmosphere, particularly the arch or loop structure of solar flare. A solar flare not only extends so widely in the atmosphere but also arises unusual changes in broad wavelength that people only can scan the parts of its 3D structure locating in the atmosphere, where opacity is very thin, directly though the information of extreme ultraviolet spectrum and ultraviolet spectrum, even the limb flare can give nothing about the sections rooting in chromosphere and photosphere because of the thick opacity.Therefore we turn to solar spectrum analysis, it is well known that solar spectrum is a rich information pool including broad continuum and thousands of emission and absorption Frauhofer lines. The line formation theory was just originated and developed for the research of depth-depended variables in the atmosphere utilizing the solar spectrum analysis. The Contribution Function as well as the Response Function derived from radiative transfer equation(s) form the line formation theory. What we are interested hi this paper is to study and explore the contribution function, and then to reconstruct the part of flare embedding in chromosphere and photosphere based on the physical meaning of the contribution function.The contribution function is to get the line formation region, describing the contribution of stellar atmospheric levels to the observed variables. In the case of theemergent spectral intensity Iv, if we regard it as the total photons escaping from solaratmosphere, the contribution function has been thought as the " probability distribution " of these escape photons at the same time. Of course, the contribution function is also wavelength dependent, thus the escape photons with definitewavelength originate from different region. Redistributing the received photons of the observed area to the layers according to the corresponding contribution functions and putting the photons together with different wavelength within a spectrum line in each layer will result in the three-dimensional image observed by this line. It is worthy noting that this process is quite different from constructing 3D image by locating the 2D observational image of different lines to their formation depths respectively.Supervised by Prof. Qu and based on the line-center and off-line-center observations of Yunnan Observatory Solar Fine Structure Telescope and 25cm refraction telescope in Big Bear Solar Observatory, I have tempted to reconstruct a series of the 2D Ho chromospheric flares images according to the physical meaning of the contribution function stated above and researched the relationship between atmosphere condition and the contribution function.