Characterization of high altitude turbulence for air force platforms

Significant progress has been made towards the goal of characterizing HAT. Simulations with a microscale code of jet stream induced turbulence for a real-world case study revealed the fine vertical scale detail of the turbulence layers. Operational mesoscale models such as WRF are able to reproduce large scale features such as the jet and waves in the stratosphere but lack the amplitude seen in the simulations presented here. Additional real data cases will be explored along with comparisons to WRF in order to build turbulence parameterizations compatible with WRF and investigate the possibility of operational use of the microscale code embedded with WRF. The different behavior observed in the Kelvin-Helmholtz simulations under differing stratifications is significant because the KH literature is dominated by the more complex transition exhibited by the low-Ri case. Such transition is stressed in the recent review by Peltier and Caulfield (2003) and is invoked in order to explain flight data by Whiteway et al. (2004). Hence, it is extremely significant that all of the observed cliff-ramp cases reported by Wroblewski et al. (2006) appear to be consistent with a flow morphology and transition that differs fundamentally from that which has received the most attention to date by theorists and those conducting numerical simulations. Continued analysis (both of observational and numerical data) is required to fully understand the significance of this result. The similar scaled structure observed with different stratifications bodes well for the ability to describe their gross dynamical behavior suitable for a mesoscale model. However the detailed mixing behavior as a function of time for the different stratifications still needs to be parameterized. This is an area of focus of continuing research for this project.