Ivic I.R.,University of Oklahoma |
Ivic I.R.,National Oceanic and Atmospheric Administration |
Krause J.C.,Radar Operations Center |
Krause J.C.,Centuria Corporation |
And 6 more authors.
Journal of Atmospheric and Oceanic Technology | Year: 2014
A radar antenna intercepts thermal radiation from various sources, including the ground, the sun, the sky, precipitation, and man-made radiators. In the radar receiver, this external radiation produces noise that constructively adds to the receiver internal noise and results in the overall system noise. Consequently, the system noise power is dependent on the antenna position and needs to be estimated accurately. Inaccurate noise power measurements may lead to a reduction of coverage if the noise power is overestimated or to radar data images cluttered by noise speckles if the noise power is underestimated. Moreover, when an erroneous noise power is used at low to moderate signal-to-noise ratios, estimators can produce biased meteorological variables. Therefore, to obtain the best quality of radar products, it is desirable to compute meteorological variables using the noise power measured at each antenna position. An effective technique that achieves this by estimating the noise power in real time from measured powers at each scan direction and in parallel with weather data collection has been proposed. Herein, the effects of such radial-based noise power estimation on spectral moment estimates are investigated. © 2014 American Meteorological Society.
Melnikov V.M.,University of Oklahoma |
Lee R.R.,Radar Operations Center |
Langlieb N.J.,Radar Operations Center
IEEE Geoscience and Remote Sensing Letters | Year: 2012
It is shown that the scattering resonance effects in echoes from migrating birds are so strong that a 10% frequency deviation within S-band can result in more than 10-dB changes in reflectivity values. Differential reflectivity values from adjacent polarimetric WSR-88D weather radars operating at offset frequencies can differ by several decibels in clear air echoes. © 2012 IEEE.