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  • Author or Editor: R. M. Johnson x
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S. L. Durden, M. A. Fischman, R. A. Johnson, A. J. Chu, M. N. Jourdan, and S. Tanelli

Abstract

Measurement of precipitation Doppler velocity by spaceborne radar is complicated by the large velocity of the satellite platform. Even if successive pulses are well correlated, the velocity measurement may be biased if the precipitation target does not uniformly fill the radar footprint. It has been previously shown that the bias in such situations can be reduced if full spectral processing is used. The authors present a processor based on field-programmable gate array (FPGA) technology that can be used for spectral processing of data acquired by future spaceborne precipitation radars. The requirements for and design of the Doppler processor are addressed. Simulation and laboratory test results show that the processor can meet real-time constraints while easily fitting in a single FPGA.

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E. A. Early, P. Y. Barnes, B. C. Johnson, J. J. Butler, C. J. Bruegge, S. F. Biggar, P. R. Spyak, and M. M. Pavlov

Abstract

Laboratory measurements of the bidirectional reflectance distribution function (BRDF) of diffuse reflectors are required to support calibration in the Earth Observing System (EOS) program of the National Aeronautics and Space Administration. To assess the ability of the instrument calibration laboratories to perform accurate BRDF measurements, a round-robin with the National Institute of Standards and Technology (NIST) as the central laboratory was initiated by the EOS Project Science Office. The round-robin parameters include sample type, wavelength, and incident and viewing angles. The results show that the participating calibration laboratories are, with a few exceptions due to experimental techniques or sample properties, generally able to measure BRDF for the round-robin parameters to within 2% of the values measured by NIST.

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A. B. White, M. L. Anderson, M. D. Dettinger, F. M. Ralph, A. Hinojosa, D. R. Cayan, R. K. Hartman, D. W. Reynolds, L. E. Johnson, T. L. Schneider, R. Cifelli, Z. Toth, S. I. Gutman, C. W. King, F. Gehrke, P. E. Johnston, C. Walls, D. Mann, D. J. Gottas, and T. Coleman

Abstract

During Northern Hemisphere winters, the West Coast of North America is battered by extratropical storms. The impact of these storms is of paramount concern to California, where aging water supply and flood protection infrastructures are challenged by increased standards for urban flood protection, an unusually variable weather regime, and projections of climate change. Additionally, there are inherent conflicts between releasing water to provide flood protection and storing water to meet requirements for the water supply, water quality, hydropower generation, water temperature and flow for at-risk species, and recreation. To improve reservoir management and meet the increasing demands on water, improved forecasts of precipitation, especially during extreme events, are required. Here, the authors describe how California is addressing their most important and costliest environmental issue—water management—in part, by installing a state-of-the-art observing system to better track the area’s most severe wintertime storms.

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