1:45 PM - 2:00 PM
[ACG45-01] Observations of a Drainage Flow Using an UAV
Keywords:drone, UAV, drainage flow
At calm and clear night, radiative cooling of the surface generates cold air parcel on slopes. The cold, heavy air l descends the slope as gravity current: this phenomenon is called drainage flows. Although observations of the vertical structure of drainage flows were conducted in previous studies, it has been difficult to obtain high-resolution vertical profiles of air temperature and wind speed. Therefore, the objective of this study is to clarify the dynamics of drainage flows using UAVs, generally called drones, and surface observations.
We conducted observations at Kamigamo Experimental station of Kyoto University. This site is surrounded by slopes on three sides and has a topography of a valley, and the elevation change is about 70 m. This field is considered suitable for observations of drainage flows.
In this research, we used two drones (Phantom 4) which is each equipped with an ultrasonic anemometer (TriSonica Mini) and a meteorological sensor (iMet-XQ2). These can obtain vertical profiles of horizontal wind velocity, sound virtual temperature, and mixing ratio. Surface observations were also conducted to measure wind velocity, sound virtual temperature, net radiation, and so on.
Observations were conducted from late afternoon to sunset on a clear day, and vertical profiles were obtained by flying the drones approximately every 30 minutes. We observed in this method several times from 2022 to 2023. In addition, nocturnal observations were also carried out, having flied UAVs every hour from late afternoon to early morning of the next day.
Through these observations, we succeeded in capturing the drainage flows in high resolution. The profile of temperature showed a clear inversion layer. A typical vertical structure of wind was also observed in the inversion layer, with a maximum wind speed near the middle and a minimum wind speed at the upper end. Such a vertical structure has been confirmed in almost all measurements , and the presentation will also include observation accuracy and surface observation results.
We conducted observations at Kamigamo Experimental station of Kyoto University. This site is surrounded by slopes on three sides and has a topography of a valley, and the elevation change is about 70 m. This field is considered suitable for observations of drainage flows.
In this research, we used two drones (Phantom 4) which is each equipped with an ultrasonic anemometer (TriSonica Mini) and a meteorological sensor (iMet-XQ2). These can obtain vertical profiles of horizontal wind velocity, sound virtual temperature, and mixing ratio. Surface observations were also conducted to measure wind velocity, sound virtual temperature, net radiation, and so on.
Observations were conducted from late afternoon to sunset on a clear day, and vertical profiles were obtained by flying the drones approximately every 30 minutes. We observed in this method several times from 2022 to 2023. In addition, nocturnal observations were also carried out, having flied UAVs every hour from late afternoon to early morning of the next day.
Through these observations, we succeeded in capturing the drainage flows in high resolution. The profile of temperature showed a clear inversion layer. A typical vertical structure of wind was also observed in the inversion layer, with a maximum wind speed near the middle and a minimum wind speed at the upper end. Such a vertical structure has been confirmed in almost all measurements , and the presentation will also include observation accuracy and surface observation results.