Radar Seeing Mayflies, Dual-Polarized Radar Helping

National Weather Service Doppler Radar appears to have detected mayflies on the Mississippi River on Thursday night, May 17th, 2012 around 850pm.  The latest radar upgrade to Dual Polarization detected these mayflies most notably on the Differential Reflectivity (ZDR) product, likely due to the long and skinny body of the mayfly.  The ZDR value grows when a target is more horizontal than vertical. The ZDR radar image below clearly shows how the targets along the river stand out to the eye.

The Correlation Coefficient (CC) tells how uniform the targets are that are being sampled. Meteorological targets typically occur in the 0.90 to 1.0 range. The echo on the river, which probably was mayflies, had CC values in the 0.30 to 0.70 range.

The radar also performs an analysis of all the data and determines the most likely target type. This Hydrometeor Classification (HC) analyzed a biological target. 

Some images from the National Weather Service La Crosse's radar at 850 pm.

4 Panel Image of Reflectivity, Differential Reflectivity, Correlation Coefficient, and Hydrometeor Classification

4 Panel Combination

Reflectivity of Mayfly Hatch - May 17th, 2012

Reflectivity

Differntial Reflectivity of a Mayfly Hatch on Thursday, May 17th, 2012

Differential Reflectivity (ZDR)

Correlation Coefficient of a Mayfly Hatch from Thursday, May 17th, 2012

Correlation Coefficient (CC)

Hydrometeor Classification of a Mayfly Hatch from Thursday, May 17th, 2012

Hydrometeor Classification (HC)



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