caa a22 4500 445345756 CHVBK 20180317142828.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s11207-010-9611-7 doi (NATIONALLICENCE)springer-10.1007/s11207-010-9611-7 Determining Absorption, Emissivity Reduction, and Local Suppression Coefficients inside Sunspots [Elektronische Daten] [Stathis Ilonidis, Junwei Zhao] The power of solar acoustic waves is reduced inside sunspots mainly due to absorption, emissivity reduction, and local suppression. The coefficients of these power-reduction mechanisms can be determined by comparing time - distance cross-covariances obtained from sunspots and from the quiet Sun. By analyzing 47 active regions observed by SOHO/MDI without using signal filters, we have determined the coefficients of surface absorption, deep absorption, emissivity reduction, and local suppression. The dissipation in the quiet Sun is derived as well. All of the cross-covariances are width corrected to offset the effect of dispersion. We find that absorption is the dominant mechanism of the power deficit in sunspots for short travel distances, but gradually drops to zero at travel distances longer than about 6°. The absorption in sunspot interiors is also significant. The emissivity-reduction coefficient ranges from about 0.44 to 1.00 within the umbra and 0.29 to 0.72 in the sunspot, and accounts for only about 21.5% of the umbra's and 16.5% of the sunspot's total power reduction. Local suppression is nearly constant as a function of travel distance with values of 0.80 and 0.665 for umbrae and whole sunspots respectively, and is the major cause of the power deficit at large travel distances. Springer Science+Business Media B.V., 2010 Helioseismology nationallicence Sunspots nationallicence Absorption nationallicence Emissivity reduction nationallicence Local suppression nationallicence Acoustic waves nationallicence Ilonidis Stathis W.W. Hansen Experimental Physics Laboratory, Stanford University, 94305-4085, Stanford, CA, USA aut Zhao Junwei W.W. Hansen Experimental Physics Laboratory, Stanford University, 94305-4085, Stanford, CA, USA aut Solar Physics Springer Netherlands 268/2(2011-02-01), 377-388 0038-0938 268:2<377 2011 268 11207 https://doi.org/10.1007/s11207-010-9611-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11207-010-9611-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ilonidis Stathis W.W. Hansen Experimental Physics Laboratory, Stanford University, 94305-4085, Stanford, CA, USA aut NATIONALLICENCE 700 1- Zhao Junwei W.W. Hansen Experimental Physics Laboratory, Stanford University, 94305-4085, Stanford, CA, USA aut NATIONALLICENCE 773 0- Solar Physics Springer Netherlands 268/2(2011-02-01), 377-388 0038-0938 268:2<377 2011 268 11207 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer