Performance of a Proposed Hybrid Spectrum Width Estimator for the NEXRAD ORDA
Gregory Meymaris, NCAR, Boulder, CO; and J. K. Williams and J. C. Hubbert
Spectrum width, a measurement of the variability of the radial wind velocities within a pulse volume, has been shown to be useful in the remote detection of aircraft-experienced in-cloud turbulence. The standard pulse-pair estimator of spectrum width, which uses the zeroth and first lags of the autocorrelation function of the I&Q time-series, has been shown to have biases and large errors for low signal-to-noise ratios and/or small true spectrum widths. The other standard pulse-pair estimator, based on the first and second lags, does better in those regimes but has serious and unexpected problems when the estimator saturates. With the introduction of the Open Radar Data Acquisition on the WSR-88D Radars comes the possibility of improving the estimation of spectrum widths. In this paper, we present a hybrid spectrum width estimator, which is being proposed to replace the current spectrum width estimator on the WSR-88D, that synthesizes the results from simpler estimators to end up with a superior spectrum width estimate. This is a simple approach that takes advantage of the relative strengths of the simpler estimators. The performance characteristics of this hybrid estimator are compared with those of the standard pulse-pair estimators.
Extended Abstract (320K)
Session 11B, Radar Applications - Session II - Part II
Wednesday, 14 January 2009, 4:00 PM-5:30 PM, Room 122BC
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