Assessment of Vertical Profile Correction for Quantitative Precipitation Estimation using S-band Radar in Northern Taiwan

The quantitative precipitation estimation (QPE) products are well known that tend to underestimate due to the beam broadening effect, partial beam blockage (PBB) effect, vertical microphysical evolution, and sampling discrepancy. The underestimation of the QPE is most pronounced for the precipitation with pronounced low-level enhancement due to warm rain processes. This study assessed the vertical profile (VP) correction for the radar-based QPE of S-band polarimetric radar at various types of precipitation events from 2017 to 2022. In addition, the retrieved K_DP from self-consistency method (K_DP^*) was investigated to reduce the uncertainties of deriving specific differential phase (K_DP) in light rain. The results of the real case study indicate that the R(K_DP^*) shows improvement reaching up to 15% at low rain rates compared to the range-derivative K_DP-based QPE. Moreover, the VP-R(K_DP^*) shows significant improvement in the regions where the PBB effect is most severe. The improvements are most pronounced during the stratiform precipitation event with the normalized mean bias decreasing by 25%. On the other hand, the VP correction shows a slightly impact to the heavy precipitation events.

Keyword
Radar-based quantitative precipitation estimation
Vertical profile correction
Partial beam blockage
Specific differential phase