Fig. 4

Typical common echo layer structures. Eight different cases of likely PBL evolution are shown, labeled (1) to (7). Panels a and b [cases (1) and (2)] correspond to continuous growth with full development of the PBL echoes as observed on February 18th, 2014 and December 28th, 2013, respectively. Panel c shows the case of February 8th, 2014 where no observable PBL echoes were found. Panel d) contains a case of truncated linearly growing PBL echoes (3) observed on April 7th, 2014. Cases for January 9th, May 4th, March 11th and February 13th (2014 for all the cases) are presented in panels e, f, g, and h, as (4), (5), (6), and (7), respectively, and exemplify linear growth of the echoes at the top of the PBL top. Note that the layers generally have different ascension rates