Radars provide a useful means of determining winds in the upper atmosphere by means of the shift in frequency of the returned signal (the doppler shift) that is proportional to the wind speed and defined in altitude by the range measurement of the radar. At nighttime the ionosphere largely recombines below 100km and there is an absence of scatterers in the 50 to 100 km region, except for the ionized tails of meteors. (Meteors are the visual manifestation of the penetration into the atmosphere of tiny fragments of interplanetary material, mostly the size of a grain of sand or smaller, with occasionally a larger one, that mostly burn up on entry). The meteor radar data reveal the presence of tides, planetary waves, seasonal and solar cycle variations in winds. This award is for analysis of a 13 year set to be prepared for the CEDAR data base and made available to the Aeronomy community generally, and used in the generation of models of middle atmosphere winds.
