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Paper: Comparison of Ca IIK and Ca II 8542Å Images
Volume: 368, The Physics of Chromospheric Plasmas
Page: 151
Authors: Reardon, K.P.; Cauzzi, G.; Rimmele, T.
Abstract: We compare a time sequence of filtergrams obtained in the Ca IIK line with a series of spectrally resolved images obtained simultaneously with the IBIS instrument in the Ca II 8542Å line. Using the narrowband IBIS images and a synthetic filter profile, we construct simulated 8542 filtergrams that mimic the observed K2V filtergrams. We observe that these filtergrams appear to contain elements corresponding to both photospheric and chromospheric structures. Intermediate scale patterns seen in the filtergrams may simply be the result of the combination of a variety of structures from different atmospheric levels. We analyze the Fourier power spectra of the filtergrams and note that at frequencies well above the acoustic cut-off value the observed power in the K2V filtergrams seems to be predominantly photospheric in origin. The use of Ca IIH and K filtergrams to study the chromospheric behavior thus may be inherently problematic. Narrowband images in the Ca II 8542Å line might provide a better source of information about chromospheric behavior with little loss in spatial or temporal resolution.
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