12:00 PM - 12:15 PM
[AAS13-12] Evolution of convective clouds initiated over mountains observed by Ka-band scanning Doppler radar and stereo photogrammetry
★Invited papers
It is known that convective storms are frequently initiated over mountains in warm and humid environment. According to previous studies, shallow cumuli initiated over heated mountains develop into a deep convective storm. However, the transition process from shallow to deep convection is not well understood due to a lack of observation data. In order to elucidate this problem, we observed convective clouds initiated over mountains in Kanto, Japan on 18 August 2011 using a 35 GHz scanning Doppler radar and a pair of digital cameras. The first cloud observed over the mountains reached the 6 km level, while the maximum echo-top height was about 1 km lower than the cloud top. The maximum radar reflectivity in the cloud was about 10 dBZ found around the 2 to 3 km levels. The reason why the echo-top altitude was lower than the cloud-top height was considered to be due to the mixing with surrounding dry air. After such shallow cumuli appeared three times repeatedly, a deep convective cloud developed. These results are consistent with a "pre-conditioning" hypothesis, that shallow cumuli moisten midlevel air and produce favorable condition for development of deep convective storms.