Christopher Ruf

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A new type of microwave radiometer detector has been developed that is capable of identifying high and low levels of radio-frequency interference (RFI) and of reducing or eliminating its effect on the measured brightness temperatures. High-level, localized RFI can be easily identified by its unnatural appearance in brightness temperature imagery. Low-level(More)
A physically based model is developed to determine hot calibration reference brightness temperatures (TBs) over depolarized regions in the Amazon rain forest. The model can be used to evaluate the end-to-end calibration of any satellite microwave radiometer operating at a frequency between 18 and 40 GHz and angle of incidence between nadir and 55°. The(More)
The coldest possible brightness temperatures observed by a downward-looking microwave radiometer from space are often produced by calm oceans under cloud-free skies and very low humidity. This set of conditions tends to occur with sufficient regularity that an orbiting radiometer will accumulate a useful number of observations within a period of a few days(More)
A new type of microwave radiometer detector that is capable of identifying low-level pulsed radio frequency interference (RFI) has been developed. The Agile Digital Detector can discriminate between RFI and natural thermal emission signals by directly measuring other moments of the signal than the variance that is traditionally measured. The kurtosis is the(More)
The Naval Research Laboratory WindSat polarimetric radiometer was launched on January 6, 2003 and is the first fully polarimetric radiometer to be flown in space. WindSat has three fully polarimetric channels at 10.7, 18.7, and 37.0 GHz and vertically and horizontally polarized channels at 6.8 and 23.8 GHz. A first-generation wind vector retrieval algorithm(More)
A new type of calibration standard is presented which produces a pair of microwave noise signals to aid in the characterization and calibration of correlating radiometers. The Correlated Noise Calibration Standard (CNCS) is able to generate pairs of broad bandwidth stochastic noise signals with a wide variety of statistical properties. The CNCS can be used(More)
A retrieval algorithm is presented for the Level 2 ocean surface wind speed data product of the Cyclone Global Navigation Satellite System (CYGNSS) mission. The algorithm is based on the approach described by Clarizia et al., 2014. The approach is applied to the specific orbital measurement geometry, antenna, and receiver hardware characteristics of the(More)
The TOPEXPoseidon Microwave Radiometer (TMR) is a three-frequency radiometer flown on the TOPEXPoseidon (T/P) satellite in low Earth orbit. It operates at 18, 21, and 37 GHz in a nadir-only viewing direction which is co-aligned with the T/P radar almeters. TMR monitors and corrects for the propagation path delay of the altimeter radar signal due to water(More)
The design, error budget, and preliminary test results of a 50–56-GHz synthetic aperture radiometer demonstration system are presented. The instrument consists of a fixed 24-element array of correlation interferometers and is capable of producing calibrated images with 1◦ spatial resolution within a 17◦ wide field of view. This system has been built to(More)
The calibrated antenna temperatures measured by the TOPEX Microwave Radiometer are used to derive radiometric brightness temperatures in the vicinity of the altimeter footprint. The basis for the procedure devised to do this-the antenna pattern correction and brightness temperature algorithm-is described in this paper, along with its associated(More)