The method generally used to perform rainfall intensity estimates with conventional weather radars is that of estimating rainfall intensity from reflectivity factor ZH (the so-called R-ZH method). Since this method is sensitive to fluctuations in raindrop size distribution, it is known that there are substantial errors in rainfall intensity estimates. On the other hand, one feature of the R-KDP method, which uses specific differential phase, is that it is not so sensitive to fluctuations in raindrop size distribution. Simulations show that the R-KDP method has an estimation error of below 30 percent, while the Z-R method has an estimation error of 100 percent or more.

The R-ZH relationship obtained by measured raindrop size distribution through simulation.	The R-KDP relationship obtained by measured raindrop size distribution through simulation.
Comparison between actual rainfall intensity (transverse axis) and rainfall intensity obtained using the R-ZH relation (longitudinal axis). The dispersion of points shows that this method is sensitive to fluctuation in raindrop size distribution.	Comparison between actual rainfall intensity and rainfall intensity obtained using the R-KDP relation. The dispersion is smaller than that obtained when the traditional method was used.