Shigaraki UAV-Radar Experiment (ShUREX): overview of the campaign with some preliminary results

Abstract

The Shigaraki unmanned aerial vehicle (UAV)-Radar Experiment (ShUREX) is an international (USA-JapanFrance) observational campaign, whose overarching goal is to demonstrate the utility of small, lightweight, inexpensive, autonomous UAVs in probing and monitoring the lower troposphere and to promote synergistic use of UAVs and very high frequency (VHF) radars. The 2-week campaign lasting from June 1 to June 14, 2015, was carried out at the Middle and Upper Atmosphere (MU) Observatory in Shigaraki, Japan. During the campaign, the DataHawk UAV, developed at the University of Colorado, Boulder, and equipped with high-frequency response cold wire and pitot tube sensors (as well as an iMET radiosonde), was flown near and over the VHF-band MU radar. Measurements in the atmospheric column in the immediate vicinity of the radar were obtained. Simultaneous and continuous operation of the radar in range imaging mode enabled fine-scale structures in the atmosphere to be visualized by the radar. It also permitted the UAV to be commanded to sample interesting structures, guided in near real time by the radar images. This overview provides a description of the ShUREX campaign and some interesting but preliminary results of the very first simultaneous and intensive probing of turbulent structures by UAVs and the MU radar. The campaign demonstrated the validity and utility of the radar range imaging technique in obtaining very high vertical resolution (~20 m) images of echo power in the atmospheric column, which display evolving fine-scale atmospheric structures in unprecedented detail. The campaign also permitted for the very first time the evaluation of the consistency of turbulent kinetic energy dissipation rates in turbulent structures inferred from the spectral broadening of the backscattered radar signal and direct, in situ measurements by the highfrequency response velocity sensor on the UAV. The data also enabled other turbulence parameters such as the temperature structure function parameter C 2 T and refractive index structure function parameter C 2 n to be measured by sensors on the UAV, along with radar-inferred refractive index structure function parameter C 2 n;radar . The comprehensive dataset collected during the campaign (from the radar, the UAV, the boundary layer lidar, the ceilometer, and radiosondes) is expected to help obtain a better understanding of turbulent atmospheric structures, as well as arrive at a better interpretation of the radar data.

Midlevel Cloud‐Base Turbulence: Radar Observations and Models

“…These are indicative of strong convective motions present in these layers. Figure shows TKE and ε , deduced from measured radar spectral width after appropriate corrections for spectral broadening, using the method described in Wilson et al (; see also Kantha et al, and Luce et al, ). High TKE and ε levels of similar magnitude can be seen both in the MCT and CBL layers.…”

Vertical structure of the lower troposphere derived from MU radar, unmanned aerial vehicle, and balloon measurements during ShUREX 2015

“…Lawrence and Balsley (2013) and describe the design of the UAVs, the characteristics of ground support components, and some data collected from these systems. Kantha et al (2017) describe the specific characteristics of the UAVs during the ShUREX 2015 campaign. The UAVs were equipped with various sensors for measurements of various atmospheric parameters.…”

“…Nearly co-located and simultaneous measurements from instrumented Unmanned Aerial Vehicles (UAV) , balloon-borne radiosondes, and the 46.5 MHz middle and upper atmosphere (MU) radar were made for the first time at the Shigaraki MU observatory during the ShUREX (Shigaraki UAV Radar Experiment) campaign in June 2015. Kantha et al (2017) describe the experimental set up and present preliminary results for illustrating the potential of the collected datasets. Luce et al (2018) took advantage of the UAV echoes in the MU radar Doppler spectra for an ultimate validation and evaluation of a frequency domain interferometry technique used to improve the range resolution of the radar.…”

“…The layout of the paper is as follows. In the section "Experimental/Methods," instruments and datasets are first briefly described [see also Kantha et al 2017] and a short outline of the methods used for deriving the atmospheric parameters from the different datasets is given among with references for more details. In the section "Results," time-height cross-sections of parameters measured by the MU radar are first analyzed in order to document the conditions met during the UAV/balloon flights.…”

On the estimation of vertical air velocity and detection of atmospheric turbulence from the ascent rate of balloon soundings

“…For this purpose, vertical profiles of V B are compared with profiles of turbulence kinetic energy (TKE) dissipation rate ε estimated from unmanned aerial vehicle (UAV) data and from 46.5 MHz middle and upper atmosphere (MU) radar data. These data were gathered during Shigaraki UAV-Radar Experiment (ShUREX) campaigns at the Shigaraki MU observatory (Kantha et al, 2017). In addition, the MU radar provided coincident estimates of vertical air velocities so that quantitative comparisons with V B could be made.…”