Daniel Michaud
School of Meteorology
The University of Oklahoma, Norman, OK
Atmospheric Radar Research Center, Norman, OK
14 May 2009, 1:00 PM
National Weather Center, Room 5600
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK
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Over the last year, radar-derived refractivity has been continuously estimated at the University of Oklahoma using two Oklahoma WSR-88D radars (KTLX, KFDR). Refractivity is calculated using phase measurements derived from stationary clutter targets in the radar's domain, which is typically limited to 40–60 km due to earth curvature. Previous work has shown the utility of short-term refractivity changes as a proxy for low-level moisture perturbations. These may in turn be used as a predictor for focal points of convection initiation.
An error analysis is shown using a comparison of radar refractivity with refractivity derived from Oklahoma Mesonet stations. Error sources are shown, which range from atmospheric stratification, beam propagation changes and quality of ground clutter targets. The latter is partially mitigated by current quality control (QC) methods. However, it remains a possibility that questionable phase data is not being censored, impacting surrounding data points up to a distance of 4 km and providing estimates of phase and refractivity with degraded quality. An improved phase QC methodology will be proposed. Future work will include a determination of clutter targets with undesirable phase data using spectral characteristics and phase coherency, and subsequent censoring of these targets so as to improve estimates of the refractivity field.
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