Spatiotemporal Profiling of Tropical Cyclones Genesis and Favorable Environmental Conditions in the Western Pacific Basin

We analyze the spatiotemporal variations of tropical cyclone (TC) genesis and associated environmental conditions over the western North Pacific with a series of data science techniques, including Gaussian kernel estimator, wavelet, cross-wavelet coherence, and regression analyses. There are significant semiannual and annual variations of TC genesis over the northern South China Sea and oceanic areas east of the Philippines. Variations on the El Nino-Southern Oscillation timescale are prominent between 5-10 degrees N, 155-160 degrees E. With reconstructed TC series on those frequencies, we further quantify the influences of environmental variables on the primary TC signals over western North Pacific. Over northern South China Sea and oceanic areas east of the Philippines, 40% of the reconstructed TC variance can be explained by vertical shear of zonal wind, relative humidity, and absolute vorticity. The reconstructed TC series near (160 degrees E, 7 degrees N) has strong but varying in-phase relationships with El Nino-Southern Oscillation, which provides deeper insight into their nonstationary and nonlinear relations than their modest correlation.