Use of Thermal Image Velocimetry to Measure a Dust-Devil-Like Vortex Within a Sports Ground in a Residential Area

Abstract

We investigate the characteristics of a dust-devil-like vortex (DDLV) observed using thermal image velocimetry (TIV) at a sports ground in Tokyo. Thermal image velocimetry provides unique observations of the two-dimensional velocity distribution for a DDLV with high spatio–temporal resolution (i.e., tens of cm s−1) near the ground. Two DDLVs were detected, one each in summer and winter, and the quantitative features of the larger, stronger DDLV in the winter are examined. The size and strength of the detected DDLV, which are quantified using TIV, are within the ranges reported in past observations and numerical simulations of dust devils. The vortex appears at the boundary of a cold-air current near a 55-m building wall, and persists for more than 3 min.