The characteristics of magnetohydrodynamic fast wave propagation in the solar stratified atmosphere are studied by the ray tracing method. The propagation behaviour of the wavefronts is described in detail. A magnetic...The characteristics of magnetohydrodynamic fast wave propagation in the solar stratified atmosphere are studied by the ray tracing method. The propagation behaviour of the wavefronts is described in detail. A magnetic field incorporating the characteristics field spreading expected in flux tubes is used, which represents the main feature of an active region. Partly ionization is considered beside the stratified solar atmosphere consisting chromosphere, transition region and corona. The study may explain the characteristics in observations of Moreton and extraultraviolet image telescope （EIT） waves. The wavefront incurred by the disturbance initialized at the base of the transition region propagates fast initially due to strong magnetic field, and it slows down when arriving beyond the region of flux-tube. Meanwhile, the wave propagates in the corona with a more consistent speed, as seen in the observation of EIT waves. The speeds and propagated characteristics in chromosphere and corona of the wavefronts are in agreement with those observed in H~ Moreton and EIT waves, respectively.展开更多
In ground-based observations of the Sun,solar images are often affected by appearance of thin clouds,which contaminate the images and affect the scientific results from data analysis.In this paper,the improved Pixel t...In ground-based observations of the Sun,solar images are often affected by appearance of thin clouds,which contaminate the images and affect the scientific results from data analysis.In this paper,the improved Pixel to Pixel Network(Pix2Pix)network is used to convert polluted images to clear images to remove the cloud shadow in the solar images.By adding attention module to the model,the hidden layer of Pix2Pix model can infer the attention map of the input feature vector according to the input feature vector.And then,the attention map is multiplied by the input feature map to give different weights to the hidden features in the feature map,adaptively refine the input feature map to make the model pay attention to important feature information and achieve better recovery effect.In order to further enhance the model’s ability to recover detailed features,perceptual loss is added to the loss function.The model was tested on the full disk H-alpha images datasets provided by Huairou Solar Observing Station,National Astronomical Observatories.The experimental results show that the model can effectively remove the influence of thin clouds on the picture and restore the details of solar activity.The peak signal-to-noise ratio(PSNR)reaches 27.3012 and the learned perceptual image patch similarity(LPIPS)reaches 0.330,which is superior to the existed dehaze algorithms.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 40274050 and 40336052, and the National Key Basic Research Special Foundation of China under Grant No G2000078405.
文摘The characteristics of magnetohydrodynamic fast wave propagation in the solar stratified atmosphere are studied by the ray tracing method. The propagation behaviour of the wavefronts is described in detail. A magnetic field incorporating the characteristics field spreading expected in flux tubes is used, which represents the main feature of an active region. Partly ionization is considered beside the stratified solar atmosphere consisting chromosphere, transition region and corona. The study may explain the characteristics in observations of Moreton and extraultraviolet image telescope （EIT） waves. The wavefront incurred by the disturbance initialized at the base of the transition region propagates fast initially due to strong magnetic field, and it slows down when arriving beyond the region of flux-tube. Meanwhile, the wave propagates in the corona with a more consistent speed, as seen in the observation of EIT waves. The speeds and propagated characteristics in chromosphere and corona of the wavefronts are in agreement with those observed in H~ Moreton and EIT waves, respectively.
基金Funding for this study was received fromthe open project of CASKey Laboratory of Solar Activity(Grant No:KLSA202114)the crossdiscipline research project of Minzu University of China(2020MDJC08).
文摘In ground-based observations of the Sun,solar images are often affected by appearance of thin clouds,which contaminate the images and affect the scientific results from data analysis.In this paper,the improved Pixel to Pixel Network(Pix2Pix)network is used to convert polluted images to clear images to remove the cloud shadow in the solar images.By adding attention module to the model,the hidden layer of Pix2Pix model can infer the attention map of the input feature vector according to the input feature vector.And then,the attention map is multiplied by the input feature map to give different weights to the hidden features in the feature map,adaptively refine the input feature map to make the model pay attention to important feature information and achieve better recovery effect.In order to further enhance the model’s ability to recover detailed features,perceptual loss is added to the loss function.The model was tested on the full disk H-alpha images datasets provided by Huairou Solar Observing Station,National Astronomical Observatories.The experimental results show that the model can effectively remove the influence of thin clouds on the picture and restore the details of solar activity.The peak signal-to-noise ratio(PSNR)reaches 27.3012 and the learned perceptual image patch similarity(LPIPS)reaches 0.330,which is superior to the existed dehaze algorithms.
