Comparisons between high-resolution profiles of squared refractive index gradient <i>M</i><sup>2</sup> measured by the Middle and Upper Atmosphere Radar and unmanned aerial vehicles (UAVs) during the Shigaraki UAV-Radar Experiment 2015 campaign
New comparisons between the square of the generalized potential refractive index gradient <i>M</i><sup>2</sup>, estimated from the very high-frequency (VHF) Middle and Upper Atmosphere (MU) Radar, located at Shigaraki, Japan, and unmanned aerial vehicle (UAV) measurements...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-03-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/35/423/2017/angeo-35-423-2017.pdf |
| Summary: | New comparisons between the square of the
generalized potential refractive index gradient <i>M</i><sup>2</sup>, estimated from the
very high-frequency (VHF) Middle and Upper Atmosphere (MU) Radar, located at Shigaraki, Japan, and unmanned aerial
vehicle (UAV) measurements are presented. These comparisons were performed at
unprecedented temporal and range resolutions (1–4 min and ∼ 20 m,
respectively) in the altitude range ∼ 1.27–4.5 km from simultaneous
and nearly collocated measurements made during the ShUREX (Shigaraki
UAV-Radar Experiment) 2015 campaign. Seven consecutive UAV flights made
during daytime on 7 June 2015 were used for this purpose. The MU Radar was
operated in range imaging mode for improving the range resolution at vertical
incidence (typically a few tens of meters). The proportionality of the radar
echo power to <i>M</i><sup>2</sup> is reported for the first time at such high time and
range resolutions for stratified conditions for which Fresnel scatter or a
reflection mechanism is expected. In more complex features obtained for a
range of turbulent layers generated by shear instabilities or associated with
convective cloud cells, <i>M</i><sup>2</sup> estimated from UAV data does not reproduce
observed radar echo power profiles. Proposed interpretations of this
discrepancy are presented. |
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| ISSN: | 0992-7689 1432-0576 |