Colloquium: Tuesday, 7 April 2009, EN6085A, 2:45 pm (NOTE TIME CHANGE)

The Earth Observing Laboratory (EOL) of NCAR is in the process of building the first phase of a three phase dual wavelength W/Ka-band airborne cloud radar to be called the HIAPER Cloud Radar (HCR). This phase is a pod based W-band radar system with scanning capability. The second phase will add pulse compression and polarimetric capability to the W-band system, while the third phase will add a complimentary Ka-band radar. The pod-based radar is primarily designed to fly on the Gulfstream V (GV) and C-130 aircraft. It is a part of the HIAPER (High-performance Instrumented Airborne Platform) Aircraft Instrumentation Solicitation (HAIS).

One of the attractive features of a millimeter wave radar system is its ability to detect micron-sized particles that constitute clouds with lower than 0.1 g m-3 liquid or ice water content. The engineering specifications of such a radar are mainly driven by climate, Earth’s radiation budget, and cloud initiation studies. The envisioned capability of a millimeter wave radar system on HIAPER is enhanced by coordination with microwave radiometer, in situ probes, and especially by the NCAR GV High-Spectral Resolution Lidar (HSRL) which is also under construction.  The lidar, designed and built by the University of Wisconsin, provides unique measurements of optical depth of clear air, clouds and precipitation.   The combination of the lidar and cloud radar can be used to measure cloud fraction, precipitation rate, and scattering cross sections.  Furthermore, the lidar/radar estimate of particle size coupled with Doppler velocity can provide information on particle shape.

The radar measurements would be critical for quantifying both kinematics and microphysical parameterization schemes in cloud modeling and verifying temporal and spatial scales of cloud systems.

This presentation describes engineering overview of the initial phase of the HIAPER airborne cloud radar on the GV, as well as the multi-phase design approach being taken. The expected measurement capabilities of system for each phase of development are also presented.