MCS Stratiform and Convective Regions Associated with Sprites Observed from Mt. Fuji

Five sprites produced above the stratiform region and one sprite above the convective region in the mesoscale convective system (MCS) were observed on 22 July 2013 from the summit of Mt. Fuji. Four of the five sprites occurred in the stratiform region after the stratiform region was cut off from the convective region. The five sprite-producing +CGs (SP + CGs) occurred in and close to these cells with low lightning activity, although in-cloud lightning locations extensively spread out in the stratiform region. This suggests that positive charges were sufficient to produce the SP + CGs that accumulated extensively in the stratiform region due to a local (in situ) charge generation mechanism. One sprite occurred above the MCS convective region, and the SP + CG was also located at the MCS convective region. Video images indicated that the optical cloud flash associated with the SP + CG continued at least 150 ms until sprite emission. The optical cloud flash light occurred repeatedly at strong and weak intensities, and this characteristic indicated that the M components in the lightning occurred in the cloud. The SP + CG might have gathered sufficient positive charges to produce the sprite with a continuing current.