Outline

  • Abstract
  • Introduction
  • Methods/experimental
  • Results and Discussion
  • Typical Atmospheric Structures Seen During Shurex Campaigns
  • Mid-Level Cloud-Base Turbulent Convective Layers
  • Kelvin-Helmholtz Instability and Billow Structures
  • Convective Boundary Layer
  • Sheet and Layer (s&l) structures
  • Structures with Wave-Like Oscillations
  • Conclusions
  • Additional Files
  • Abbreviations
  • Acknowledgements
  • Funding
  • Availability of Data and Materials
  • Authors’ Contributions
  • Authors’ Information
  • Competing Interests
  • Publisher’s Note
  • Author Details
  • References

رئوس مطالب

  • چکیده
  • کلیدواژه ها
  • مقدمه
  • روش ها/ آزمایشات
  • نتایج و بحث
  • ساختارهای رایج جوی مشاهده شده در طول کمپین های shUREX
  • لایه های نوسانی و همرفتی در سطوح میانی ابرها
  • ساختارهای موجی و بی ثباتی کلوین- هلمهولتز
  • لایه مرزی همرفتی
  • ساختارهای لایه و صفحه (S&L)
  • سازه های دارای نوسانات موجی
  • نتیجه گیری ها
  • منابع

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, ever-changing evolution of atmospheric structures over the MU radar.


Conclusions

The high-resolution Capon images from the MU radar, operated in range-imaging mode (Luce et al. 2001, Luce et al. 2010, Luce et al. 2018a) during the ShUREX campaigns revealed a variety of atmospheric structures in great detail. It was also possible to see their evolution in time. We have presented and discussed some examples of such structures of potential importance to atmospheric dynamics. However, it is best to see videos of the radar images to appreciate the evolution of these features. As such, we have presented three videos as Additional files 1, 2 and 3, with a brief explanatory text as Additional file 4 It is our hope that these videos persuade ST radar operators around the world to implement range-imaging mode of operation on at least the vertical beam of their radars, so that it is possible to visualize the evolution of atmospheric features above those radars.

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