Gravity Wave and Turbulence Studies Using a High-Resolution ST Radar

Abstract

Abstract : Research under this contract addressed a number of aspects of gravity wave propagation and effects in the lower and middle atmosphere. Observational studies utilized data sets collected at several radar installations and in situ data obtained during two major rocket campaigns. Theoretical studies examined wave instability and ducting, the relationship between neutral and ion density fluctuations in the presence of chemically active species, and the potential for energy exchange due to resonant wave interactions. Our results showed the motion spectrum in the troposphere, stratosphere, and mesosphere to be highly anisotropic, with an upward flux of horizontal momentum largely opposed to the large-scale mean flow. The motion spectrum was found largely to be consistent with gravity wave theory and saturation. These findings have important implications for the forcing of the mean circulation of the lower and middle atmosphere. Theoretical studies revealed low-frequency motions to favor dynamical instabilities and suggested that resonant wave interactions are not likely to be a major factor for energy transfer in the middle atmosphere due to the rapid vertical transport and dissipation of energy.