Poster Session P11B.12 Validation of polarimetric methods for attenuation correction at C band

Thursday, 9 August 2007
Halls C & D (Cairns Convention Center)
Alexander V. Ryzhkov, CIMMS/Univ. of Oklahoma, Norman, OK; and P. Zhang, D. Hudak, J. L. Alford, M. Knight, and J. W. Conway

Handout (1.0 MB)

Polarimetric methods for attenuation correction of radar reflectivity Z and differential reflectivity ZDR utilize measurements of differential phase ΦDP which is immune to attenuation. Simplified versions of the attenuation correction techniques assume that the coefficients of proportionality α and β between the Z and ZDR biases and ΦDP do not vary much. However, at C band these are highly variable in convective cells containing large raindrops and hail due to effects of resonance scattering. More sophisticated schemes for attenuation correction attempt to estimate the coefficients α and β in such “hotspot” cells using additional constraints.

In this paper, we evaluate the performance of the attenuation correction techniques with different degree of complexity using C-band data collected with the Environment Canada King radar in Southern Ontario, Canada, and the EEC Sidpol radar in Alabama, USA.

Nearby S-band WSR-88D radars in Buffalo and Panama City are used to validate attenuation correction of Z. Checking consistency between corrected Z and specific differential phase KDP is another validation tool.

The criteria of spatial and temporal continuity of the ZDR fields as well as consistency with expected values of ZDR in dry aggregated snow and light rain are utilized to assess the quality of differential attenuation correction.

Statistical analysis of variable coefficients α and β in “hotspots” reveals noticeable differences in microphysical processes which determine precipitation formation in Ontario and Alabama.

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