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Bluestein H.B.,University of Oklahoma | French M.M.,University of Oklahoma | Popstefanija I.,ProSensing | Bluth R.T.,Naval Postgraduate School, Monterey | Knorr J.B.,Naval Postgraduate School, Monterey
Bulletin of the American Meteorological Society | Year: 2010

A meteorological weather radar 2005 X-band phased array (MWR-05XP) modified by ProSensing Inc., was used to study severe convective storms and tornadoes on very short time scales and relatively close range. Two radars employed frequency hopping to generate more independent samples and this hopping also allowed pulse pairs to be formed at a common frequency for Doppler velocity estimation. MWR-05XP was field tested in the US Great Plains in 2007 and 2008 when the likelihood of severe weather migrates northward with the upper-level westerlies. The radar probed a tornado at a range of 20-25 km in northeast Oklahoma showing a well-defined hook echo and evidence of a trailing rear-flank gust front and a cyclonic vortex signature coincident with the tip of the hook. The number of tornadic supercells probed showed that none of the supercells were isolated and there were nearby neighboring or connected storms. Source

Mead J.B.,ProSensing
Journal of Atmospheric and Oceanic Technology | Year: 2016

Detection of meteorological radar signals is often carried out using power averaging with noise subtraction either in the time domain or the spectral domain. This paper considers the relative signal processing gain of these two methods, showing a clear advantage for spectral-domain processing when normalized spectral width is less than ~0.1. A simple expression for the optimal discrete Fourier transform (DFT) length to maximize signal processing gain is presented that depends only on the normalized spectral width and the time-domain weighting function. The relative signal processing gain between noncoherent power averaging and spectral processing is found to depend on a variety of parameters, including the radar wavelength, spectral width, available observation time, and the false alarm rate. Expressions presented for the probability of detection for noncoherent and spectral-based processing also depend on these same parameters. Results of this analysis show that DFT-based processing can provide a substantial advantage in signal processing gain and probability of detection, especially when the normalized spectral width is small and when a large number of samples are available. Noncoherent power estimation can provide superior probability of detection when the normalized spectral width is greater than ~0.1, especially when the desired false alarm rate exceeds 10%. © 2016 American Meteorological Society. Source

Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 750.00K | Year: 2015

ABSTRACT: This Phase II SBIR proposal describes our effort to develop a combined radiometer and radar sensor to estimate total atmospheric path loss for potential satellite links at V-band and W-band (71-86 GHz). Termed WAXRR, for W-band and X-band Radar Radiometer, this system will be used to generate statistics of total atmospheric loss with a dynamic range exceeding 20 dB. The radiometer section of WAXRR is suitable for measuring total path attenuation under clear or nearly clear sky conditions, while the dual-frequency radar is intended for measuring loss in the presence of stronger clouds and precipitation. The WAXRR system is readily transportable and hosts its own website for remote instrument control and display. BENEFIT: Atmospheric loss statistics generated over a two-year time period in Phase III will be used by the Air Force in evaluating the satellite link budget and potential outage rates at potential sites for satellite ground stations. Commercial applications include profiling super-cooled liquid water above airports for assessing aircraft icing potential and the development of compact, pod-mounted radars and radiometers for airborne cloud and water vapor remote sensing.

Zuidema P.,University of Miami | Leon D.,University of Wyoming | Pazmany A.,ProSensing | Cadeddu M.,Argonne National Laboratory
Atmospheric Chemistry and Physics | Year: 2012

Routine liquid water path measurements and water vapor path are valuable for process studies of the cloudy marine boundary layer and for the assessment of large-scale models. The VOCALS Regional Experiment respected this goal by including a small, inexpensive, upward-pointing millimeter-wavelength passive radiometer on the fourteen research flights of the NCAR C-130 plane, the G-band (183 GHz) Vapor Radiometer (GVR). The radiometer permitted above-cloud retrievals of the free-tropospheric water vapor path (WVP). Retrieved free-tropospheric (above-cloud) water vapor paths possessed a strong longitudinal gradient, with off-shore values of one to two mm and near-coastal values reaching ten mm. The VOCALS-REx free troposphere was drier than that of previous years. Cloud liquid water paths (LWPs) were retrieved from the sub-cloud and cloudbase aircraft legs through a combination of the GVR, remotely-sensed cloud boundary information, and in-situ thermodynamic data. The absolute (between-leg) and relative (within-leg) accuracy of the LWP retrievals at 1 Hz (∼100 m) resolution was estimated at 20 g m-2 and 3 g m-2 respectively for well-mixed conditions, and 25 g m-2 absolute uncertainty for decoupled conditions where the input WVP specification was more uncertain. Retrieved liquid water paths matched adiabatic values derived from coincident cloud thickness measurements exceedingly well. A significant contribution of the GVR dataset was the extended information on the thin clouds, with 62 % (28 %) of the retrieved LWPs <100 (40) g m -2. Coastal LWPs values were lower than those offshore. For the four dedicated 20 S flights, the mean (median) coastal LWP was 67 (61) g m -2, increasing to 166 (120) g m-2 1500 km offshore. The overall LWP cloud fraction from thirteen research flights was 63 %, higher than that of adiabatic LWPs at 40 %, but lower than the lidar-determined cloud cover of 85 %, further testifying to the frequent occurrence of thin clouds. © 2012 Author(s). CC Attribution 3.0 License. Source

Goodberlet M.A.,ProSensing | Mead J.B.,ProSensing | Mead J.B.,University of Massachusetts Amherst
IEEE Transactions on Geoscience and Remote Sensing | Year: 2012

Microwave radiometer measurements of the Planck emission from soil can be used to estimate the near-surface soil moisture. A more straightforward and consistent model of this emission results if nonuniform, rather than uniform, plane waves are used. Adaptation of this new model to a layered medium representation for the soil is improved using a normalization that is based on the isothermal soil limit. The separate concepts of radiometer sensing depth and in situ sampling depth for soil moisture are examined and theory for the sensing depth is presented. Improved approximations (at 1413 MHz) to the full model for soil emission are developed since they are needed to construct algorithms that retrieve an estimate of soil moisture from the radiometer raw measurement. The error associated with the comparison of these remotely sense values against in situ measurements is calculated. Results suggest that this comparison error could be lowered if the soil moisture sampling depth was reduced to values less than 0.01 m from the currently used values near 0.02 m, although the effect of surface roughness has not yet been analyzed. © 2012 IEEE. Source

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