地形に起因する線状対流系の数値標高モデル感度実験 --自己組織化構造におけるマルチフラクタル的性質--

Abstract

Complex topography can force lift up moisture air and cause convection initiation of linear-shaped convective systems. The current study conducted sensitivity experiments of the digital elevation models (DEM) for three heavy rainfall events to examine the topographic effects in terms of accumulated rainfall, and multifractality of water vapor flux and turbulence kinetic energy (TKE). The results showed that the accumulated rainfall of the experiments in which the terrain height was obtained by 30 m resolution DEM got greater than the one with coarser resolution DEM, especially near or the downstream side of the steep slope. The former experiments showed a much amount of topographically induced vertical moisture flux, causing the strong updraft and the resulting compensating flow. Multifractal analysis revealed that water vapor flux and TKE on the organization of rainfall systems show strong multifractality, which corresponds to increasing moisture inflow and upscaling the clouds.