Develop New Capabilities That Focus On Processes at Interfaces in the Atmosphere.
The air-sea interface, the air-land interface, and the tropopause have diverse observational needs: ships, buoys, and aircraft for the first; facilities such as ISFS for the second; and a high-altitude aircraft (perhaps supplemented by high-altitude wind profilers) for the third. EOL has provided excellent support for studies of the air-land interface, but the inability to characterize surface fluxes below hurricanes is a particular aspect of the air-sea interface that could be examined, because it limits the accuracy with which hurricanes can be modeled. In high-wind conditions, research aircraft have been unable to fly low enough to provide good characterization of the momentum and other fluxes that govern hurricane development, and as a result there is considerable uncertainty regarding how to represent such fluxes in models. Similarly, the capabilities of the GV were used in the START-08 experiment to study UTLS dynamics and chemistry and will likely be of increasing importance to studies of the UTLS as the suite of instruments for air chemistry is completed (in 2012).
There are many possible measurement tools and observational opportunities for these interfaces: controlled towed vehicles to extend the reach of research aircraft closer to the surface; possible deployment of ocean sensors like Airborne eXpendable BathyThermographs (AXBTs) for studies of the upper layer of the ocean; measurements of fluxes of trace gases to or from the lower surface (land or sea); new sensors on dropsondes for characterizing the chemistry of the tropopause region; scintillometry as an inexpensive way to extend measurements of near-surface wind and turbulence; the development of remote sensors that measure profiles of trace gases and remote sensors for measurement of fluxes (e.g., via combining a DIAL lidar with a Doppler lidar); and development of large arrays of sensors to increase coverage and resolution of measurements. Other areas with potential include using UASs for boundary-layer studies, the remote measurement of 3-D wind, tethersonde capability to increase the altitude range of B-L measurements, and higher-response measurements from research aircraft to measure fluxes and probe the fine-scale structure of turbulence. Understanding processes at interfaces continues to grow in importance and is prominent in many assessments of needs for the future.
An additional theme that EOL is exploring is the need for greater coverage through longer timeframes, broader areas, and complex terrain. Sensor simplification and miniaturization is leading to new opportunities in this area. EOL is developing an innovative, modular 449 MHz wind profiler network to expand and replace our 915 MHz boundary-layer wind profiling capability. As a basic boundary-layer wind profiler, the new system will probe higher and be simpler to deploy. The 449 MHz profiler’s unique hexagonal-antenna and its modular design will provide for assembly in a variety of configurations to meet the diverse range of experiments that EOL supports. The envisioned system could be deployed as a network of six boundary-layer profilers, a single full-tropospheric profiler, or variations in between. Advanced hardware and innovative signal processing such as spaced antenna winds, range imaging, and adaptive clutter suppression are important features of the 449 MHz profiler development effort. A prototype of the 449 MHz profiler was successfully deployed during the recent PCAPS project in Utah (see Imperative II).