Dual-polarization radar products for biological applications

The upgrade of the national network of next-generation weather surveillance radars (NEXRAD) in the United States to dual polarizations has been completed, providing three additional routine data products: total differential phase (psi(DP)), differential reflectivity (Z(DR)), and copolar correlation coefficient (rho(HV)). The application and interpretation of these products in the context of aerial bird, bat, and insect movements is an actively developing research front, with potential implications for ecological and conservation studies. The following conceptually derives the definition of these products specifically for NEXRAD weather surveillance radars in the case of biological scatterers. Several cases are presented that illustrate characteristic values and variability of polarimetric quantities for birds and insects, and highlight site-specific differences within the NEXRAD network. Finally, a short prospectus of future directions and applications within the field of polarimetric radar aeroecology is outlined.