Relationship of Tropical Cyclone Size with ENSO

Suzana J. Camargo¹ and John A. Knaff²

1 Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY

2 Regional and Mesoscale Meteorology Branch, NOAA/NESDIS, Fort Collins, CO

Recently, a tropical cyclone size satellite-based dataset was developed (Knaff et al. 2014). Estimates of the radius of 5kt winds (R5) or TC size are available for all basins for the period 1978-2013. The climatological characteristics of TC size show interesting properties, varying by basin, TC intensity and latitude. Here we further analyze this dataset, by considering the dependence of TC size with the phases of the El Niño-Southern Oscillation (ENSO) in various basins. Preliminary results in the North Atlantic and western North Pacific, show that the TC size distributions in these basins are statistically significant distinct in El Niño and La Niña years. In the Atlantic, La Niña years tend to have a higher (lower) percentage of small (big) storms than in El Niño and neutral years. In contrast, the western North Pacific, in La Niña years, has lower percentage of small TCs than in El Niño and neutral years. These shifts in the TC size distribution are not the same for all types of storms, with different TC size distributions shifts with ENSO phase for tropical storms, hurricanes and major hurricanes. In the North Atlantic, the increase in the percentage of small storms in La Niña years is due to a higher occurrence of small size tropical storms and minor hurricanes. In contrast, the distribution of Atlantic major hurricanes shows a shift towards a higher percentage of large storms in La Niña years. In this talk, we will present our preliminary results of how TC size distributions in all basins vary with ENSO and TC characteristics, such as intensity, lifetime, latitude, and seasonality.

Reference:
Knaff, J.A., S.P. Longmore, and D.A. Molenar, 2014: An objective satellite-based tropical cyclone size climatology. J. Climate, 27, 455-476.