Spatial periodicity of L1 loop and its evolution. Panels a)–f) show a temporal sequence of the L1 loop in the period of 12:24:48 UT –12:26:48 UT. Five bright blobs are indicated with crosses on panel a). Panel b) shows a one pixel cut from starting point S to the ending point E, and the corresponding de-trended intensity curves (black) are shown on panel g), fitted with the function asin (bx + c) with the red lines. Intensity varies by ±2000DN. The blobs do not show significant movement. Panel c) shows four intensity minima points between neighboring bright blobs.