Evaluation of HWRF for Typhoon Prediction over the western North Pacific Ocean in 2012-2013

Taiwan Typhoon and Flood Research Institute (TTFRI) collaborated with Central Weather Bureau (CWB) and NOAA Earth System Research Laboratory to implement the operational Hurricane WRF (HWRF) system in Taiwan. The configuration of HWRF system in TTFRI is similar with the HWRF system in NCEP Environmental Modeling Center (EMC) except GSI data assimilation.

TTFRI conducts full typhoon season forecast experiment in 2012-2013 using a corresponding operational HWRF system from NCEP EMC for each year, however the GSI data assimilation system is not applied on the western North Pacific since the real time observation data for GSI system is unavailable in TTFRI. We have the forecast results for typhoons in 2012-2013 from the NCEP EMC, and we do the comparison between TTFRI and EMC HWRF system. The result of track verification shows that TTFRI HWRF without GSI data assimilation system is slightly better than EMC HWRF. It improves about 12.5% (17 typhoons included) and 7% (14typhoons included) at 72 forecast hour in each year. Besides, we conduct a forecast experiment using 2012 operational HWRF system in 2013 typhoon season to compare the performance between 2012 and 2013 HWRF system. Result shows that with the upgraded of model physics and infrastructure of HWRF system, 2013 HWRF system has a better typhoon track forecast ability and it improves about 25% (14 typhoons included) at 72 forecast hour.