Assessing global ensemble systems’forecasts of tropical cyclone genesis in differing environmental flow regimes in the western North Pacific  

作　　者：Yasuhiro Kawabata Munehiko Yamaguchi Hironori Fudeyasu Ryuji Yoshida 

机构地区：[1]Meteorological Research Institute,Japan Meteorological Agency,Tsukuba,Japan [2]Graduate School of Education,Yokohama National University,Yokohama,Japan [3]Graduate School of Environment and Information Sciences,Yokohama National University,Yokohama,Japan [4]Typhoon Science and Technology Research Center,Yokohama National University,Yokohama,Japan

出　　处：《Tropical Cyclone Research and Review》2024年第4期344-355,共12页热带气旋研究与评论(英文版)

摘　　要：The forecast probability of tropical cyclone(TC)genesis in the western North Pacific from 2017 to 2020 was investigated using global ensembles from the Japan Meteorological Agency(JMA),the European Centre for Medium-Range Weather Forecasts(ECMWF),the U.S.National Centers for Environmental Prediction(NCEP),and the Met Office in the United Kingdom(UKMO).The time of TC genesis was defined as the time the TCs were first recorded in the best-track data(Case 1)and as the time they reached the intensity of a Tropical Storm(Case 2).The results in Case 1 showed that differences between the forecast probability based on each global ensemble were large,even for a 1-day forecast,and that mean probability were from 18%to 74%.The forecasts based on the NCEP had a large frequency bias and overpredicted TC genesis events.The results indicated that the representation of genesis events differed greatly between global ensembles.The effectiveness of multiple ensembles was investigated.The results from the threat score and the false alarm ratio indicated that multiple ensembles had skillful forecasts.When the forecast probability was examined for environmental patterns of synoptic low-level flow,the mean 5-day forecast probability was highest for the pattern in the confluence region.The results also showed that the forecast probability was much larger in Case 2 than in Case 1.In all global ensembles,the mean probability with a lead time of up to 1-week was below 10%for both Case 1 and 2.This result indicates that even with today's operational forecasting systems,it is difficult to regularly predict TC genesis events with a 1-week lead time with high confidence.These results provide a better understanding of TC genesis forecast products in each global ensemble and will be useful information when multiple-ensemble products are created.

关 键 词：Tropical cyclone TYPHOON GENESIS Ensemble forecast Genesis environment 

分 类 号：P45[天文地球—大气科学及气象学]