Abstract
Turbulent structure within the atmospheric boundary layer is dependent on the atmospheric condition and the geometric nature of the surface. Surface horizontal wind field is among its important indicators. However, its measurements are still limited. Recently, a method to estimate the two-dimensional wind field, called "Thermal Image Velocimetry" (TIV), was established. The concept is based upon the relationship between the changes in surface temperature measured by a thermographic camera and the near-surface wind speeds. TIV has successfully detected wind fields near building walls and vortices similar to dust devils, which has tens of meters scale. To date, its applicability to larger spatial scales is still unknown. In this study, we applied TIV to a larger scale by conducting an aerial observation on-board a helicopter. A rough consistency with stationary observation data was confirmed and the wind fields were determined. The outcome of this study suggests the possibility of applying TIV to wider scales, hundreds of meters, in spite the condition where the camera is not fully stationary.
