Fig. 2: Evolution and distribution of NBEs.
From: Polarity transitions of narrow bipolar events in thundercloud tops reaching the lower stratosphere
a Height and occurrence variations of NBEs. Blue and red triangles represent negative and positive NBEs, respectively. The identification of NBEs and error evaluation for the NBE height are given in Methods. b Histogram for the height of NBEs and the inferred charge region; blue for the negative charge region and red for the positive charge region based on the temperature profile obtained from the balloon sounding profile. c Time series of positive NBEs and negative NBEs, respectively; the time bin size is 5 min. d Histogram of the proportion of the dominant number of positive or negative polarity to the total number (PDP). The grid with the sum of NBEs larger than 5 and at least one negative NBE is counted. A total of 115 grids meet the criteria and are used to count the histogram of the proportion of PDP.
