This project addresses four themes: waves, electric fields, winds and temperatures. The Middle and Upper Atmosphere radar's phased-array construction facilitates the wave work. By observing in multiple directions simultaneously, the PI can distinguish temporal variations over the radar and spatial variations caused by features moving over the radar. He will use this capability to detect gravity-wave propagation over the radar. These waves, almost always present, are best observed in daytime conditions near the peak of the ionosphere. The PI plans to observe waves in the drift velocity in addition to density, study the altitude profile of these waves and their dissipation, and map out their spatial structure. Measurements of electric fields will contribute to developing global electric field models. These electric fields (during solar maximum) show interesting global relationships based on consideration of magnetic conjugacy and summer-hemisphere control of a magnetic field line based on seasonal differences in electrical-conductivity. The PI plans to extend his study to solar minimum, as well as compare data with other radars to test hypotheses made with solar maximum data. MU measurements of thermospheric neutral winds show smaller speeds than do winds at other longitudes. The expanded winds database the PI plans will contribute improvement to current wind models. The PI will also examine this data set for signatures of global wind circulation systems originating from different global processes: direct solar heating, auroral thermal forcing, and equatorial momentum forcing. Finally, he will investigate neutral and ionospheric temperatures, both to develop models of their behavior and to aid in the interpretation of radar Doppler and power data.
