Atmospheric structures in the troposphere as revealed by high-resolution backscatter images from MU radar operating in range-imaging mode

Abstract

VHF band stratosphere/troposphere (ST) radars around the globe are seldom operated in range-imaging mode. As such, the typical range resolution of their backscatter images is about 150 m. The only exception is the Kyoto University's Middle and Upper Atmosphere (MU) radar in Shigaraki, Japan. Range imaging using frequency diversity was implemented there in 2005 and has often been used since then. During the Shigaraki UAV Radar Experiment (ShUREX) campaigns in the spring/summers of 2015, 2016, and 2017, the MU radar was operated in range-imaging mode to provide a range resolution of typically 20 m, for good signal to noise (SNR) ratios. The resulting Capon backscatter images revealed a variety of atmospheric structures in the moist troposphere in great detail. They were also quite useful in deploying in situ sensors on board unmanned aerial vehicles (UAVs) to probe such structures in near real time guided by the images. The goal of this paper is to present and discuss some such structures of interest to atmospheric dynamics collectively, to provide an overarching view. They include Kelvin-Helmholtz (KH) billows generated by shear instability, mid-level cloud-base turbulence (MCT) layers generated by convective instability in a moist troposphere, convective boundary layer (CBL), and sheet and layer (S&L) structures in a stably stratified atmospheric column. Videos of radar images collected during the 2015 and 2016 campaigns are included as Additional files 1, 2 and 3 with a brief explanatory text as Additional file 4 to demonstrate the fascinating, everchanging evolution of atmospheric structures over the MU radar.

Instabilities, Dynamics, and Energetics accompanying Atmospheric Layering (IDEAL): high-resolution in situ observations and modeling in and above the nocturnal boundary layer

“…The precursor DH1 was used in campaigns in Peru (Balsley et al, 2013;Lawrence and Balsley, 2013;Scipión et al, 2016) and Utah (Balsley et al, 2018;Fernando et al, 2015). The DH2 was used in campaigns in Japan (Kantha et al, 2017(Kantha et al, , 2019Luce et al, 2018a, b, 2019), Colorado (de Boer et al, 2019), and Alaska (de Boer et al, 2018. To date, over 650 science flights have been performed with the DH2, totaling 430 h of flight.…”

“…Under stable conditions, the vertical structure of the atmosphere is characterized by thin, strongly stable non-turbulent "sheets" separated by thicker, less stable, and often weakly turbulent "layers" (Woods, 1969(Woods, , 1968Gage and Green, 1978;Röttger and Liu, 1978). These sheet and layer (S&L) structures are often observed in temperature, humidity, and horizontal winds within the lower troposphere (Balsley et al, , 2006Chimonas, 1999;Mahrt, 1999;Xing-Sheng et al, 1983;Kantha et al, 2019) and into the edge of the stratosphere (Barat, 1982;Fairall et al, 1991;Gage and Balsley, 1980;Röttger, 1980;Woodman and Guillen, 1974). The S&L structures are known to play an important role in the transport and mixing of heat, momentum, and constituents (Barat, 1982;Chimonas, 1999;Dalaudier et al, 1994;Hunt et al, 1985), as well as important roles in optical (Coulman et Published by Copernicus Publications on behalf of the European Geosciences Union.…”

The DataHawk2 uncrewed aircraft system for atmospheric research

“…Objectives of these campaigns ranged from calibrating radar returns against in situ turbulence measurements, making radar-guided measurements of shear-driven Kelvin-Helmholtz instabilities (KHI) in stratified layers, observing mid-level cloud-base turbulence (MCT), and quantifying turbulence growth in the convective boundary layer (CBL). These three campaigns yielded 86 DataHawk flights and over 112 h of measurements, with analysis results reported in Kantha et al (2017), Kantha and Luce (2018), Kantha et al (2019, 2018a, b, 2019. These flights were conducted in Japanese national airspace, with prior approval up to 5 km MSL in the area around the MU radar.…”