“…The GJ established a direct path of an electrical connection between the cloud top and the ionosphere (Cummer et al, 2009;Kuo et al, 2009), which has an important influence on the electron density and potential of the ionosphere, electromagnetic environment of the near space, and radio communication. Since the first GJ was observed on 14 September 2001 by Pasko et al (2002) in Puerto Rico, several GJs have been observed by ground-based (Cummer et al, 2009;He et al, 2019;Lu et al, 2011;Peng et al, 2018;Soula et al, 2011;Su et al, 2003;Van der Velde et al, 2007 and satellite-based experiments (Boggs et al, 2019;Chen et al, 2008;Kuo et al, 2009). Optical observations show that most of the observed GJs have "tree" or "carrot" shape (Liu et al, 2015;Pasko et al, 2002;Soula et al, 2011;Su et al, 2003) and there is a color transition zone between the two areas where the bottom (altitude 20-40 km) is blue and the top (altitude over 65 km) is red (Peng et al, 2018;Soula et al, 2011).…”