[A-AS23_28PM1] 稠密観測によるマイクロ・スケール大気現象研究の新展開

[AAS23-14] 顕著な竜巻をもたらしたスーパーセル近傍の環境場の時間変化

*荒木 健太郎¹、石元 裕史¹、村上 正隆¹、田尻 拓也¹ (1.気象研究所)

キーワード：竜巻, スーパーセル, マイクロ波放射計, 1DVAR

We examined proximity soundings at intervals of a few minutes and at distances of less than 20 km from a significant tornadic (SIGTOR) supercell that occurred on 6 May 2012 in Japan. We used a 1-dimensional variational (1DVAR) technique that combined the observations of a ground-based microwave radiometer with outputs from a numerical model. Based on the results of the 1DVAR, several supercell and tornado forecast parameters were calculated and compared with values typical of SIGTOR supercell environments in the United States. One and a half hours before the occurrence of the tornado, the value of convective available potential energy increased significantly to about 1000 J kg^-1, a value that is smaller than the typical value in the United States. Low-level vertical wind shear and some composite parameters attained maximum values at the time when the distance to the supercell was the smallest. The vertical wind shear parameters and some composite parameters indicated that the environment fell into the SIGTOR supercell category. This result shows that the thermodynamic environments became unstable before the approach of the supercell, and the low-level vertical wind shear changed locally near the supercell.