The temporal and spatial evolution of MHD wave modes in sunspots

• DOI: 10.48550/arxiv.2305.19418
• Publication Date: 2023-01-01
• Authors: A. B. Albidah; V. Fedun; Anwar Ali Aldhafeeri; I. Ballai; D. B. Jess; W. Brevis; J. Higham; M. Stangalini; S. S. A. Silva; C. D. MacBride; G. Verth
• Keywords: Sunspot; Mode (computer interface)

Through their lifetime sunspots undergo a change in area and shape and, as they decay, fragment into smaller structures. Here, for the first time we analyze spatial structure of magnetohydrodynamic (MHD) slow body fast surface modes observed umbrae cross-sectional changes. The Proper Orthogonal Decomposition (POD) Dynamic Mode (DMD) techniques were used to 3 6 hours SDO/HMI series Doppler velocities at photospheric level approximately circular elliptically shaped sunspots. Each divided equally intervals, evidence sunspots' shape. To identify physical wave modes, POD/DMD cross-correlated with mode model using exact umbra, whereas obtained by applying threshold mean intensity every interval. Our results show that MHD are affected, even apparently small changes umbral shape, especially case higher-order modes. For datasets our study, optimal intervals consider influence on is 37 - 60 minutes. choice these crucial properly quantify energy contribution each power spectrum.