Figure: PPIs of δ generated from observations on 22 June 2011 with BoXPol in 4 consecutive time steps between 11:11 UTC and 11:26 UTC. Solid lines show countours of horizontal reflectivity ZH and dashed lines indicate the 25km and 50km distance from the radar, respectively.
Backscatter differential phase δ has been identified as an important and still underutilized polarimetric variable, which should not be ignored in rainfall retrievals based on specific differential phase KDP. Figure 1 (click for animation) shows quantified δ-signals applying a strategy based on the ZPHI-method. δ is also a measure for the dominant particle size and bears information about aggregation and accretion processes.
Trömel, S., M. Kumjian, A. Ryzhkov, C. Simmer (2013): Backscatter differential phase - estimation and variability. J. Appl. Meteor. Clim., doi: http://dx.doi.org/10.1175/JAMC-D-13-0124.1.
Trömel, S., A. Ryzhkov, P. Zhang, C. Simmer (2014): Investigations of backscatter differential phase in the melting layer. J. Appl. Met. Clim., 53(10), 2344-2359 . DOI: 10.1175/JAMC-D-14-0050.1