Find in Library

<p>We describe in this study the analysis of small and large horizontal-scale gravity waves from datasets composed of images from multiple mesospheric airglow emissions as well as multistatic specular meteor radar (MSMR) winds collected in early November 2018, during the SIMONe–2018 (Spread-spectrum Interferometric Multi-static meteor radar Observing Network) campaign. These ground-based measurements are supported by temperature and neutral density profiles from TIMED/SABER (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry) satellite in orbits near Kühlungsborn, northern Germany (54.1<span class="inline-formula">^∘</span> N, 11.8<span class="inline-formula">^∘</span> E). The scientific goals here include the characterization of gravity waves and their interaction with the mean flow in the mesosphere and lower thermosphere and their relationship to dynamical conditions in the lower and upper atmosphere. We have obtained intrinsic parameters of small- and large-scale gravity waves and characterized their impact in the mesosphere via momentum flux (<span class="inline-formula"><i>F</i>_M</span>) and momentum flux divergence (<span class="inline-formula"><i>F</i>_D</span>) estimations. We have verified that a small percentage of the detected wave events is responsible for most of <span class="inline-formula"><i>F</i>_M</span> measured during the campaign from oscillations seen in the airglow brightness and MSMR winds taken over 45 h during four nights of clear-sky observations. From the analysis of small-scale gravity waves (<span class="inline-formula"><i>λ</i>_h</span> <span class="inline-formula">&lt;</span> 725 km) seen in airglow images, we have found <span class="inline-formula"><i>F</i>_M</span> ranging from 0.04–24.74 m<span class="inline-formula">²</span> s<span class="inline-formula">⁻²</span> (1.62 <span class="inline-formula">±</span> 2.70 m<span class="inline-formula">²</span> s<span class="inline-formula">⁻²</span> on average). However, small-scale waves with <span class="inline-formula"><i>F</i>_M</span> <span class="inline-formula">&gt;</span> 3 m<span class="inline-formula">²</span> s<span class="inline-formula">⁻²</span> (11 % of the events) transport 50 % of the total measured <span class="inline-formula"><i>F</i>_M</span>. Likewise, wave events of <span class="inline-formula"><i>F</i>_M</span> <span class="inline-formula">&gt;</span> 10 m<span class="inline-formula">²</span> s<span class="inline-formula">⁻²</span> (2 % of the events) transport 20 % of the total. The examination of large-scale waves (<span class="inline-formula"><i>λ</i>_h</span> <span class="inline-formula">&gt;</span> 725 km) seen simultaneously in airglow keograms and MSMR winds revealed amplitudes <span class="inline-formula">&gt;</span> 35 %, which translates into <span class="inline-formula"><i>F</i>_M</span> <span class="inline-formula">=</span> 21.2–29.6 m<span class="inline-formula">²</span> s<span class="inline-formula">⁻²</span>. In terms of gravity-wave–mean-flow interactions, these large <span class="inline-formula"><i>F</i>_M</span> waves could cause decelerations of <span class="inline-formula"><i>F</i>_D</span> <span class="inline-formula">=</span> 22–41 m s<span class="inline-formula">⁻¹</span> d<span class="inline-formula">⁻¹</span> (small-scale waves) and <span class="inline-formula"><i>F</i>_D</span> <span class="inline-formula">=</span> 38–43 m s<span class="inline-formula">⁻¹</span> d<span class="inline-formula">⁻¹</span> (large-scale waves) if breaking or dissipating within short distances in the mesosphere and lower thermosphere region.</p>