On the Similarity of Electric Field Signatures of Upward and Downward Negative Leaders

We report on general characteristics of simultaneous channel-base current and distant electric fields for five upward positive flashes recorded at the Säntis tower in Summer 2014. We describe the salient features of the upward negative leader process initiating upward positive flashes and compare them with those of the downward negative leader process found in the literature. Our observations show considerable similarity between those two processes.