Abstract
Solar telescopes will never be able to resolve the smallest events at their intrinsic physical scales. Pixel signals recorded by SOHO/(CDS, EIT, SUMER), STEREO/SECCHI/ EUVI, TRACE, SDO/AIA, and even by the future Solar Orbiter EUI/HRI contain an inherent “spatial noise” since they represent an average of the solar signal present at subpixel scales. In this paper, we aim at investigating this spatial noise, and hopefully at extracting information from subpixel scales. Two paths are explored. We first combine a regularity analysis of a sequence of EIT images with an estimation of the relationship between mean and standard deviation, and we formulate a scenario for the evolution of the local signal-to-noise ratio (SNR) as the pixel size becomes smaller. Second, we use an elementary forward modeling to examine the relationship between nanoflare characteristics (such as area, duration, and intensity) and the global mean and standard deviation. We use theoretical distributions of nanoflare parameters as input to the forward model. A fine-grid image is generated as a random superposition of those pseudo-nanoflares. Coarser resolution images (simulating images acquired by a telescope) are obtained by rebinning and are used to compute the mean and standard deviation to be analyzed. Our results show that the local SNR decays more slowly in regions exhibiting irregularities than in smooth regions.
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References
Aschwanden, M.J., Parnell, C.E.: 2002, Nanoflare statistics from first principles: Fractal geometry and temperature synthesis. Astrophys. J. 572, 1048 – 1071.
Aschwanden, M.J., Nightingale, R.W., Tarbell, T.D., Wolfson, C.J.: 2000, Time variability of the “quiet” sun observed with TRACE. I. Instrumental effects, event detection, and discrimination of extreme-ultraviolet microflares. Astrophys. J. 535, 1027 – 1046.
Berghmans, D., Clette, F., Moses, D.: 1998, Quiet Sun EUV transient brightenings and turbulence. A panoramic view by EIT on board SOHO. Astron. Astrophys. 336, 1039 – 1055.
Chatterjee, S., Hadi, A.S.: 1986, Influential observations, high leverage points, and outliers in linear regression. Stat. Sci. 1, 379 – 416.
Crosby, N.B., Aschwanden, M.J., Dennis, B.R.: 1993, Frequency distributions and correlations of solar X-ray flare parameters. Solar Phys. 143, 275 – 299.
Defise, J.M.: 1999, Analyse des performances instrumentales du téléscope spatial EIT. Ph.D. thesis, Université de Liège.
DeForest, C.E.: 2007, On the size of structures in the Solar corona. Astrophys. J. 661, 532 – 542.
Delaboudinière, J.P., Artzner, G.E., Brunaud, J., Gabriel, A.H., Hochedez, J.F., Millier, F., Song, X.Y., Au, B., Dere, K.P., Howard, R.A., Kreplin, R., Michels, D.J., Moses, J.D., Defise, J.M., Jamar, C., Rochus, P., Chauvineau, J.P., Marioge, J.P., Catura, R.C., Lemen, J.R., Shing, L., Stern, R.A., Gurman, J.B., Neupert, W.M., Maucherat, A., Clette, F., Cugnon, P., van Dessel, E.L.: 1995, EIT: Extreme-ultraviolet imaging telescope for the SOHO mission. Solar Phys. 162, 291 – 312.
Delouille, V., Patoul, J., Hochedez, J.F., Jacques, L., Antoine, J.P.: 2005, Wavelet spectrum analysis of EIT/SOHO images. Solar Phys. 228, 301 – 321.
Golub, L., Hartquist, T.W., Quillen, A.C.: 1989, Comments on the observability of coronal variations. Solar Phys. 122, 245 – 261.
Hochedez, J.F., Lemaire, P., Pace, E., Schühle, U., Verwichte, E.: 2001, Wide bandgap EUV and VUV imagers for the Solar Orbiter. In: Battrick, B., Sawaya-Lacoste, H., Marsch, E., Martinez Pillet, V., Fleck, B., Marsden, R. (eds.) Solar Encounter. Proceedings of the First Solar Orbiter Workshop 493. ESA, Noordwijk, 245 – 250.
Isliker, H., Anastasiadis, A., Vlahos, L.: 2001, MHD consistent cellular automata (CA) models. II. Applications to Solar flares. Astron. Astrophys. 377, 1068 – 1080.
Janesick, J., Klaasen, K., Elliott, T.: 1985, CCD charge collection efficiency and the photon transfer technique. In: Dereniak, E.L., Prettyjohns, K.N. (eds.) Solid State Imaging Arrays (SPIE) 570, 7 – 19.
Katsukawa, Y., Tsuneta, S.: 2001, Small fluctuation of coronal X-ray intensity and a signature of nanoflares. Astrophys. J. 557, 343 – 350.
Krucker, S., Benz, A.O.: 1998, energy distribution of heating processes in the quiet Solar corona. Astrophys. J. Lett. 501, 213 – 216.
Lin, R.P., Schwartz, R.A., Kane, S.R., Pelling, R.M., Hurley, K.C.: 1984, Solar hard X-ray microflares. Astrophys. J. 283, 421 – 425.
Paczuski, M., Boettcher, S., Baiesi, M.: 2005, Interoccurrence times in the Bak – Tang – Wiesenfeld sandpile model: A comparison with the observed statistics of Solar flares. Phys. Rev. Lett. 95(18), 181102 – 181105.
Snyder, D.L., Miller, M.I.: 1991, Random Point Processes in Time and Space, Springer, New York.
Véhel, J.L., Legrand, P.: 2004, Signal and image processing with fraclab. In: Novak, M. (ed.) Thinking in Patterns, World Scientific, Singapore, 321 – 323.
Viticchié, B., Del Moro, D., Berrilli, F.: 2006, Statistical properties of synthetic nanoflares. Astrophys. J. 652, 1734 – 1739.
Vlahos, L., Georgoulis, M., Kluiving, R., Paschos, P.: 1995, The statistical flare. Astron. Astrophys. 299, 897 – 911.
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Delouille, V., Chainais, P., Hochedez, JF. (2008). Spatial and Temporal Noise in Solar EUV Observations. In: Ireland, J., Young, C.A. (eds) Solar Image Analysis and Visualization. Springer, New York, NY. https://doi.org/10.1007/978-0-387-98154-3_17
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DOI: https://doi.org/10.1007/978-0-387-98154-3_17
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