Analysis of the Environmental Parameters between the Developing and Non-Developing Cloud Clusters for Typhoon Formation Detecting

摘要

Tropical cyclones (TCs) occur generally where there are persistent, well-structured convections, and developing cloud clusters are often to be observed before TC formations. That gives us an opportunity to compare the environmental air-sea parameters between the developing and non-developing cloud clusters, and further use the parameter differences for typhoon formation detecting. In this study, we analyzed the typhoon cases over the Northwest Pacific Ocean from 2000 to 2009. Mainly the JTWC best track and ECMWF Interim Reanalysis Data were used to determine the threshold of environmental air-sea parameters' for typhoon formations. The thresholds were further tested and verified with the typhoon cases from 2010 to 2012. The result shows that 850hPa relative vorticity, 850hPa-200hPa vertical wind shear, 900hPa divergence, and sea surface temperature present high correlations to TC formations. However, there are some TCs forming in unfavorable air-sea environments. And hence, we also adopt the Box Difference Index (BDI) weights method to decrease the false alarm rate.