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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link="#0563C1" vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoPlainText><span lang=EN-US>Dear Colleague,<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>We would like to invite you to contribute to the COSPAR-26 Scientific Assembly middle atmosphere sessions (C2). The conference will take place in Florence, Italy, from 1–9 August 2026.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>COSPAR-26-C2.1: Gravity Waves and Turbulence in the Middle Atmosphere and Lower Ionosphere, and<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>COSPAR-26-C2.2: Layered Phenomena in the Middle Atmosphere.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>C2.1: Gravity Waves and Turbulence in the Middle Atmosphere and Lower Ionosphere Gravity waves and turbulence are central to our understanding of the neutral middle atmosphere and ionosphere, yet key questions remain regarding wave generation and propagation, instabilities and wave breaking, secondary wave generation, energy transfer to turbulence, and coupling between atmospheric layers. This session aims to bring together experts working on these topics in the middle atmosphere and lower ionosphere. We welcome theoretical, modelling, experimental, and observational studies related to gravity waves or turbulence in this region.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>C2.2: Layered Phenomena in the Middle Atmosphere Physical and chemical processes in the Mesosphere and Lower Thermosphere (MLT) give rise to a rich variety of layered structures. These include metal layers formed by meteoric input and space debris, ice-related features such as noctilucent clouds (NLC), radar phenomena such as Polar Mesosphere Summer Echoes (PMSE) and Winter Echoes (PMWE), and dynamically driven structures such as mesospheric inversion layers and turbulent layers. These layers act as tracers of atmospheric dynamics and vertical coupling on timescales from seconds to decades. Recently, metal layers have gained additional relevance as indicators of anthropogenic pollution from reentering space debris. This session invites contributions on topics including middle atmosphere dynamics, long-term trends, solar-cycle effects, vertical coupling processes, and the impact of human activity on MLT composition.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>We encourage submissions that exploit synergies between different instruments, platforms, and models, and that highlight links between dynamics, chemistry, and space-weather–related impacts.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>Please submit your abstract via the COSPAR online system, selecting Commission C, Sub-Commission C2, and the appropriate session (C2.1 or C2.2).<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><a href="https://www.cospar-assembly.org/assembly.php">https://www.cospar-assembly.org/assembly.php</a><o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US>Feel free to forward this invitation to colleagues who may also be interested.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>We look forward to receiving your contribution and to an engaging set of discussions at COSPAR-26.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>With best regards,<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-US>Robin Wing, Boris Strelnikov, Michael Gerding, & Corwin Wright<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-US>COSPAR-26-C2.1 and COSPAR-26-C2.2<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div></body></html>