Evaluation of uWRF performance and modeling guidance based on WUDAPT and NUDAPT UCP datasets for Hong Kong

Abstract

The evaluation of uWRF (WRF BEP/BEM) model over Hong Kong or the Pearl River Delta region has received less attention. One reason is the lack of a complete urban canopy parameters dataset for the building morphology in the PRD region. In recent years, the World Urban Database and Access Portal Tools (WUDAPT) approach has provided an alternative estimation of the building morphology dimensions based on satelliteretrieved local climate zones (LCZs). However, several sources of uncertainty arise when implementing these data in uWRF. In this study, different methods of WUDAPT dataset implementation are carried out to isolate and quantify these sources. This study also revealed that compensation error could occur when all of the uncertainties are summed in the default W2W protocol. Nevertheless, WUDAPT remains a suitable alternative in regions where a NUDAPT type of dataset is not available, provided that building morphology for different LCZs is estimated based on local expertise with a subgrid-averaging approach. Comparison with surface stations over an urban area suggests that uWRF allows a much better simulation of wind speed than the traditional Noah Bulk urban scheme, indicating that the improvement from a multi-layer urban scheme is larger than a non-local PBL scheme over urban area.