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Table 1

Properties of synoptic map data sets used in this study.

Data set Spectral line Time span Carrington rotations Map resolution

WSO Fe 525 nm 1976.3– 1641– 72*30
MWO Fe 525 nm 1974.5–2013.0 1617–2131 971*512
Kitt Peak Fe 868.8 nm 1992.8–2003.7 1863–2006 360*180
SOLIS Fe 630.2 nm 2003.7– 2006– 1800*900
MDI Ni 676.8 nm 1996.4– 2011.1 1909–2104 3600*1080
HMI Ni 617.3 nm 2010.4– 2096– 3600*1440

Notes. Map resolution stands for the number of pixels in longitude and latitude. Grid is linear in latitude in the MWO data set and linear in sine latitude in other data sets.

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