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thermospheric wind profiles 90-140 km

Relatively strong radar returns from mesospheric heights (~55–85 km) in the winter polar region result from coherent structures of electrons and are called Polar Mesosphere Winter Echoes (PMWE). The formation mechanism of this phenomenon is not understood. All relevant parameters potentially involved in the PMWE formation were measured in a common volume and subsequently analyzed. The combined results of rocket-borne and ground-based measurements of two rocket flights conclusively show that coherent structures are created by a turbulent process involving tiny charged meteor smoke particles., Radarrückstreusignale aus der Mesosphärenregion (~55-85 km) in polaren Breiten entstehen durch Reflexionen kohärenter Elektronenstrukturen und werden Polar Mesosphärische Winter Echos (PMWE) genannt. Erstmals wurden alle relevanten Parameter, die für den Entstehungsprozess von PMWE potentiell entscheidend sind in einem gemeinsamen Volumen mittels raketengetragenen in-situ Messungen und bodengebundenen Instrumenten untersucht. Diese Messungen geben ein einheitliches Bild: Turbulenz erzeugte in Verbindung mit geladenen Meteorstaubteilchen Strukturen, die mit dem Radar beobachtet wurden.

The MST radar at Jicamarca Radar Observatory JRO is a powerful radar that can detect atmospheric turbulence on the Bragg scale of 3 m in the daytime mesosphere 60-85 km Since 2002 the radar was operated for a few days each year in the mode that collecting 1 minute Doppler spectra in four beam directions and 150 m resolution The spectral widths along with GSWM MSIS and SABER temperatures have been used to compute the kinetic energy dissipation rate due to atmospheric turbulence Eddy diffusivities K have also been calculated A small contamination due to beam broadening beam width 0 7 degree has been removed For most days median kinetic energy dissipation values of 1-10 mW kg increase with height consistent with the results from other VHF radars The variability during each day is large Turbulent dissipation rates and eddy diffusivities for individual layers and the day-to-day variability are discussed in relationship with the observed wind shear and estimated Richardson number. Tesis