Radar Suite Research Articles

Insights from modeling and observational evaluation of a precipitating continental cumulus event observed during the MC3E field campaign

AbstractA case of shallow cumulus and precipitating cumulus congestus sampled at the Atmospheric Radiation Measurement Program Southern Great Plains supersite during the Midlatitude Continental Convective Clouds Experiment is analyzed using a multisensor observational approach and numerical simulation. Observations from a new radar suite surrounding the facility are used to characterize the evolving statistical behavior of the precipitating cloud system. This is accomplished using distributions of different measures of cloud geometry and precipitation properties. Large‐eddy simulation (LES) with size‐resolved (bin) microphysics is employed to determine the forcings most important in producing the salient aspects of the cloud system captured in the radar observations. Our emphasis is on assessing the importance of time‐varying versus steady state large‐scale forcing on the model's ability to reproduce the evolutionary behavior of the cloud system. Additional consideration is given to how the characteristic spatial scale and homogeneity of the forcing imposed on the simulation influences the evolution of cloud system properties. Results indicate that several new scanning radar estimates such as distributions of cloud top are useful to differentiate the value of time‐varying (or at least temporally well‐matched) forcing on LES solution fidelity.

Field testing of robotic technologies to support ground ice prospecting in martian polygonal terrain

Polygonal terrain, a landform commonly associated with the presence of ground ice, is widespread throughout the high latitudes on Mars. In this paper, we present the results of field testing a potential mission concept for the robotic prospecting of ground ice in polygonal terrain. The focus of the paper is on the key robotic technologies that could be used to implement the concept and the engineering lessons we learned (as opposed to the specific scientific findings of our field tests). In particular, we have found that a lander- or rover-mounted lidar and a rover-borne stereo camera/ground-penetrating radar suite are two important scientific tools that may be used to help pin-point ground ice prior to subsurface sampling. We field tested some aspects of this mission concept on a previously - unstudied polygonal terrain site on Devon Island in the Canadian High Arctic (a common Mars/Moon analogue site) during the summer of 2008. This unique collaboration between technological and scientific communities has led to a deeper understanding of how such a science-driven mission could actually be implemented robotically.

Navy Radar Trades at the Ship Interface

AbstractThe next generation radar suite will include a radar that has sensitivity far greater than shipboard radars in use today. Most likely the radar will be a multi‐faced, solid state, phased array system with each array consisting of thousands of individual radiating elements powered by transmit/receive (T/R) modules. It will likely need to be large, and the demands it makes on ship services will be unprecedented. Its electrical power demands could be larger than the total ship's load for present‐day ships. Array size could significantly impact topside design. This paper examines top‐level radar system design choices and illustrates the trends in the ship impact of those choices. Radar design options considered are aperture size and shape, coolant operating temperature, number of array faces, and power system architecture. These design options have an effect on the radar system's weight, footprint, power demand, and cooling load. The effects on ship design can be significant. The ship impact analyses consider a radar system that includes ship‐provided equipment such as electrical power distribution equipment and chill water plants. An analysis of radar systems, all with the same performance, shows that radar system power demand can change by as much as four megawatts for a notional surface combatant depending upon the radar designer's configuration choices. Radar system weight can vary by more than 100 metric tons. There is a cubic relationship between T/R module power and array face area for a constant sensitivity radar system. This relationship is examined to show that there is often a choice of T/R module power that minimizes radar ship impact. The exact choice of T/R module power depends upon the customer's preferences, the manufacturer's capabilities, and choice of vendors. This paper does not convey any official US government position or US Navy endorsement of any particular radar architecture or design approach.

The ALCOR C-band imaging radar

Kwajalein Atoll, resting 9/spl deg/north of the equator and 3,500 km southwest of Hawaii, is the location of the United States Army Kwajalein Missile Range (KMR). KMR assets include a wide variety of radars, optical sensors, telemetry, missile-launch equipment, flight safety, and communications. Its radar suite, in particular, includes several highly sensitive one-of-a-kind systems. The ARPA-Lincoln C-Band Observables Radar (ALCOR) is one of four KMR instrumentation radars located on the island of Roi-Namur. Since ALCOR first began operations in 1970, it has provided C-band beacon and wideband metric and signature observations for a wide variety of range-user requirements. ALCOR has the capability to produce two-dimensional range Doppler images of near-Earth-orbiting and reentering objects. Modifications to ALCOR, its current system architecture, and future direction are described in this paper The authors provide an overview of ALCOR radar waveforms and resolution capabilities. A system description is provided, including the C-band transmitter, receiver, antenna, and digital systems.