(ACR) Airborne Cloud Radar / (CVR) CloudSat Validation Radar
The utility of millimeter-wave radars have been successfully used for cloud sensing and cloud microphysical studies. Studies of the impact of cloud feedbacks on the earth's radiation budget have underscored the importance of having a means of measuring the vertical distribution of clouds. Millimeter-wave radars can provide this information under most conditions, with high resolution, using a relatively compact system.
The Airborne Cloud Radar/CloudSat Validation Radar (ACR/CVR) for profiling cloud vertical structure was developed by the Jet Propulsion Laboratory and the University of Massachusetts in 1996. It is a W-band (95 GHz) polarimetric Doppler radar designed as a prototype airborne facility for the development of the 94 GHz Cloud Profiling Radar (CPR) for NASA CloudSat mission.
The ACR/CVR is a third-generation millimeter-wave cloud radar. While adopting the well tested techniques used by its predecessors, ACR/CVR also has a number of new features including an internal calibration loop, frequency agility, digital I and Q demodulation, digital matched filtering, and a W-band low-noise amplifier.
| Table 1. ACR/CVR's system specifications | |
| Frequency (GHz) | 94.905, 94.915, 94.925, 94.395 |
| Transmit Polarization | V or H |
| Receive Polarization | V or H |
| Peak Power (kW) | 1.2 |
| PRF (Hz) | 5,000-80,000 |
|---|---|
| Range Resolution (m) | 38, 75, 150 |
| Noise Figure (dB) | 9.5 |
| Receiver Bandwidth (MHz) | 1, 2, 4 |
| 3 dB Beamwidth (degree) | 0.8 |
| Sensitivity (dBZe, R=1 km, ΔR=75 m, 1 sec averaging) | -46 |
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| Figure 1. ACR/CVR on the DOE Twin Otter aircraft. A 45° reflector was used guide the radar beam up or down. | Figure 2. The NASA P-3 aircraft instrumented with several science instruments, including ACR/CVR, is ready to take off in one of science flights during the 2003 Wakasa Bay Experiment. | Figure 3. ACR/CVR on NASA's Twin Otter aircraft for the TWP-ICE Experiment in Darwin, Australia, December 2005 and January 2006. | Figure 4. ACR/CVR in the trailer figuration (left) for ground-based observations during the 2006-2007 CCVEX and the 2010 StormVEX Experiment in Colorado. The ACR/CVR mounting inside the trailer is shown in the right. |
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| Figure 5. ACR/CVR reflectivity profile measurements of medium-altitude cirrus clouds from ARESE II. | Figure 6. ACR/CVR’s reflectivity (top) profile measurements and the deduced snow content (bottom) of the precipitating snow clouds acquired on January 29, 2003 during the Wakasa Bay Experiment. | Figure 7. The quick-look nadir reflectivity profile measurements of convective clouds acquired by ACR/CVR aboard the Twin Otter aircraft on January 23, 2006 during the TWP-ICE Experiment. The data shown in these two panels were continuous measurements along the same flight path. | Figure 8.The quick-look vertical reflectivity profile measure-ments of mid-level clouds acquired by ACR/CVR in a ground-based, upward-looking configuration on October 31, 2006 during the C3VP. The data shown in these three panels correspond to a continuous time series of ACR/CVR measurements between 15:17 and 15:59 UTC. |
