Cluster Analysis of Typhoon Tracks. Part II: Large-Scale Circulation and ENSO

Abstract

A new probabilistic clustering technique, based on a regression mixture model, is used to describe tropical cyclone trajectories in the western North Pacific. Each component of the mixture model consists of a quadratic regression curve of cyclone position against time. The best-track 1950-2002 dataset is described by seven distinct clusters. These clusters are then analyzed in terms of genesis location, trajectory, landfall, intensity, and seasonality.Both genesis location and trajectory play important roles in defining the clusters. Several distinct types of straight-moving, as well as recurving, trajectories are identified, thus enriching this main distinction found in previous studies. Intensity and seasonality of cyclones, though not used by the clustering algorithm, are both highly stratified from cluster to cluster. Three straight-moving trajectory types have very small withincluster spread, while the recurving types are more diffuse. Tropical cyclone landfalls over East and Southeast Asia are found to be strongly cluster dependent, both in terms of frequency and region of impact.The relationships of each cluster type with the large-scale circulation, sea surface temperatures, and the phase of the El Niño-Southern Oscillation are studied in a companion paper.

Relationship between the potential and actual intensities of tropical cyclones on interannual time scales

“…On the other hand, if track changes were more predictable than changes in the PI field, and PI changes experienced by storms were dominated by track changes (as is apparently the case for observed interannual variability), that dominance could actually improve the prospects for prediction. This scenario is not far-fetched, as track changes in response to some well-known modes of climate variability do have a systematic and presumably predictable component; consider the response of tracks to El Niño and La Niña events in the western North Pacific [e.g., Chan, 2005;Camargo et al, 2007], or to the ''Atlantic Meridional Mode'' in the Atlantic [e.g., Kossin and Vimont, 2007].…”

The poleward migration of the location of tropical cyclone maximum intensity

“…Shifts in tropical cyclone tracks in most regions have also been linked to phase changes in the El Niño-Southern Oscillation [21][22][23][24] (ENSO), which can potentially contribute to the poleward trends in LMI identified here. To test this, we diminish the contribution of ENSO by regressing the latitude of LMI time series onto an index of ENSO variability.…”

A dynamical‐statistical forecast model for the annual frequency of western Pacific tropical cyclones based on the NCEP Climate Forecast System version 2

“…The variations of TC activity over the western North Pacific (WNP) are primarily due to the El Niño-Southern Oscillation (ENSO) effects by modulating the intensity and location of local monsoon trough and changing the vertical wind shear [e.g., Camargo and Sobel, 2005;Camargo et al, 2007a;Chan, 2000;Chen et al, 1998;Wu et al, 2012]. During an El Niño event, TCs tend to form over the southeastern WNP and can develop very intensively [Chan, 2000;Wang and Chan, 2002;Camargo and Sobel, 2005;Chan, 2007;Camargo et al, 2007aCamargo et al, , 2007b. Moreover, the central Pacific El Niño (also known as El Niño Modoki) events [Ashok et al, 2007] are shown to shift the TC formation westward to the western Pacific .…”