Fig. 4From: Temporal variations of plume activities before the 8 October 2016 eruption of Aso volcano, Japan, detected by ground-based and satellite measurementsMaps of the monthly averaged SO2 PBL VCDs measured by OMPS from April to October 2016. The triangle and the red and blue rectangles are as same as those in Fig. 3. The high SO2 VCDs around 140°E in longitude found in October map correspond to the SO2 cloud by the 8 October explosionBack to article page