[M-IS13] Dynamics of eruption cloud and cumulonimbus; modelling and observation

[MIS13-P02] Multi-sensor observation of cloud evolution from cumulus to cumulonimbus in Tokyo metropolitan area

*Takeshi Maesaka¹, Tadayasu Ohigashi¹, Koyuru Iwanami¹, Shin-ichi Suzuki¹, Namiko Sakurai¹, Yukari Shusse¹, Kaori Kieda¹, Shingo Shimizu¹, Yasushi Uji¹, Nobuhiro Takahashi², Hiroshi Hanado³, Katsuhiro Nakagawa³, Tomoo Ushio⁴ (1.National Research Institute for Earth Science and Disaster Resilience, 2.Nagoya University, 3.National Institute of Information and Communications Technology, 4.Osaka University)

Keywords:Cumulus, Cumulonimbus, Cloud radar, MP-PAWR

Recently, weather radar network which consists of X- and C-band polarimetric radars has matured in Japan. This nationwide network enables Quantitative Precipitation Estimation (QPE) with high resolutions (1 minute and 250 m), and is used for a monitoring of localized heavy rain. So now a social request is shifting from the monitoring to the forecast of the heavy rain. This kind of forecast needs a seed of cumulonimbus development as an initial condition. The weather radar is a suitable instrument to find the seed. But when the ordinary weather radar finds it, the rainfall has already started. To make the lead time of the forecast longer, we should monitor the pre-stages of cumulonimbus, such as horizontal convergence and cumulus clouds. For this purpose, we installed microwave radiometers, Doppler lidars, Ka-band cloud radars around Tokyo metropolitan area. Furthermore, X-band Multi-Parameter Phased Array Weather Radar (MP-PAWR) also covers the area, and is a powerful instrument to capture the three-dimensional structure of precipitation system. In this presentation, an evolution from cumulus to cumulonimbus is analyzed by using multi-sensor data.

We analyzed the cloud activities on 3 August 2018. Many cumulus clouds appeared and dissipated, before the precipitation started, cloud size and its reflectivity gradually became larger with time. Finding the clouds in transition stage (reflectivity of about -5 dBZ, and echo size of about 5 km²) is important for monitoring the evolution from cumulous to cumulonimbus. Cumulus activity moistened mid-troposphere, and this moistening may help the cumulonimbus development.