Observation of Jumping Cirrus with Ground-Based Cameras, Radiosonde, and Himawari-8

Journal of the Meteorological Society of Japan

Takafumi SEGUCHI¹  Suginori IWASAKI²  Masashi KAMOGAWA³  Tomoki USHIYAMA⁴ 

[1] Department of Earth and Ocean Sciences, National Defense Academy, Kanagawa, Japan;Department of Physics, Tokyo Gakugei University, Tokyo, Japan;International Centre for Water Hazard and Risk Management, Public Works Research Institute, Tsukuba, Japan;Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan

关键词: jumping cirrus;    ground-based camera observation;    convective cloud;    overshooting top;    above-anvil cirrus plume;   

DOI  :  10.2151/jmsj.2019-033

学科分类：大气科学

来源: Meteorological Society of Japan

【 摘 要 】

 In the summer of 2016, 14 cases of jumping cirrus (JC) were observed around the Kanto region in Japan by ground-based, visible-light cameras. The cameras were set at the summit of Mt. Fuji and National Defense Academy (Kanagawa, Japan), and 15-second time-lapse photography was continually taken for the period. The location and spatial scale of the JC were calculated by measurements using the photometry of background stars in the nighttime and the geostationary meteorological satellite Himawari-8 infrared imagery. The environmental conditions of the JC were also investigated using radiosonde and Himawari-8 visible and infrared measurements. Comparing our cases to the JC in the United States of America (USA) reproduced by a three-dimensional, non-hydrostatic cloud model from previous studies, their motions, morphology, spatial and temporal scales showed similarities, although the horizontal scale of the JC and the magnitude of the underlying convection was relatively smaller in our cases. The sounding by the radiosonde in the vicinity of the storms showed that 3 of the 14 cases reached the stratosphere. However, the hydration of the lower stratosphere was not supported by analysis of the brightness temperature difference (BTD) between 6.2 and 10.4 μm measured by Himawari-8. The averaged wind shear across the range of the jumping heights above the anvil was −1.1 m s−1 km−1. The maximum value of the convective available potential energy (CAPE) of the 14 cases was 1384 J kg−1, which is several times smaller than those of the thunderstorm cases observed in the USA in previous numerical JC studies. This indicates that JC occurs from the cumulonimbus anvil top even if the convection is relatively weak. The motion of JC observed by visible-light cameras shows that it can transport moisture above the tops of the anvils of convective clouds regardless of its altitude as cloud ice appears to be sublimated.

【 授权许可】

Unknown