Flight Plan: HIAPER will be required to penetrate mesoscale convective anvils at and above their level of neutral buoyancy in the upper troposphere and lower stratosphere. Horizontal flight legs of 200 km will be required at altitudes ranging from 40,000 to 50,000 feet MSL. Each flight will consist of alternating legs oriented parallel to the tropospheric shear vector and perpendicular to that vector. Flights should span the 3 to 6 hour period required for mesoscale anvil formation and maturation. The aircraft will be required to collect data within mixed phase clouds having up to 0.5 g/kg of supercooled liquid water. Turbulence levels within the anvil clouds are expected to include vertical gusts of 5 to 10 m/s and cloud-edge wind shears of 10 to 20 m/s. One mission scientist (with forward view) and one observer (with real-time access to the data system) will be required. Missions will be conducted in April, May, or June at in the region from north Texas through Nebraska. JeffCo would be an adequate base. All flights will be conducted in late afternoon and evening (before sunset).
Instrumentation: HIAPER will need to provide at least 100 m horizontal resolution for u, v, w, T, as well as the mixing ratios of liquid water, ice, and water vapor. Upward and downward looking radiometers for shortwave and longwave radiation will also be required, preferably also yielding 100 m or better horizontal resolution. All of these sensors must be able to operate in an environment with significant supercooled water and moderate turbulence.