Validation of Rotorcraft UAV Boundary Layer Meteorological Observation Data and Its Application in a Heavy Fog Event in Yancheng
Three experiments of boundary-layer meteorological profiles observed by rotorcraft unmanned aerial vehicle (UAV) were carried out in spring (28-30 March), summer (20-26 June) and autumn (5-13 September) 2018 respectively in Sheyang Station of Yancheng, Jiangsu Province, and compared with L-band radar sounding data to verify the accuracy of UAV observation data. The results show that the observation data of temperature, relative humidity, wind direction and wind speed vertical profile measured by UAV are in good agreement with the observation data of the L-band radar sounding data. The correlation coefficients of temperature (T), relative humidity (RH), wind direction (WD) and wind speed (WS) of UAV and L-band radar sounding are 0.98, 0.98, 0.98 and 0.91, respectively. The absolute deviations of T, RH, WD and WS are 0.57℃, 4.25%, 11.5° and 1.88 m·s-1 respectively. Since UAV measures the instantaneous wind speed at corresponding height, it can better reflect the subtle variation of wind speed characteristics in boundary layer. The summer UAV experiment recorded detailed changes of boundary layer structure during a heavy fog process. The boundary-layer structure and fog macro-characteristics observed by the UAV during this process were similar as that of L-band radar. The results show that UAV has a promising prospect in the application of boundary layer meteorological observation.