Type-I to type-IV WL emission light curves and their spatial distributions. (a1)–(a4): Light curves and spatial distribution for type-I light curves, which show a rapid enhancement with a short duration. (a1): WL emission light curve (red) at the position of (555″, −258″). The blue is the AIA 1600 Å flux at the same position. The vertical purple lines mark the start and end of the WL enhancement during the flare at the position. (a2): Average WL emission light curve (red) for this type of WL pixels. The black represents the GOES SXR 1−8 Å flux. (a3) and (a4): HMI continuum image and LOS magnetogram before the flare, respectively. The red marks indicate the position of the type-I WL pixels. The orange contours in panel a3 denote the boundary between the sunspot’s umbra and penumbra. (b1)–(b4): Type-II light curves and their spatial distribution, which exhibit a slow growth phase followed by rapid growth with a long duration. (c1)–(c4): Type-III light curves and their spatial distribution, which display two consecutive peaks for the WL emission flux. (d1)–(d4): Type-IV light curves, which are associated with a continuous upward trend in the background.