The universal scaling characteristics of tropical oceanic rain clusters

C. -K. Teo , H. -N. Huynh , T. -Y. Koh , K. K. W. Cheung , B. Legras (1) , L. Y. Chew , L. Norford

1 LMD - Laboratoire de Météorologie Dynamique (UMR 8539)

Using multiyear satellite rainfall estimates, the distributions of the area, and the total rain rate of rain clusters over the equatorial Indian, Pacific, and Atlantic Oceans was found to exhibit a power law fS(s) s-ζS, in which S represents either the cluster area or the cluster total rain rate and f_S(s) denotes the probability density function of finding an event of size s. The scaling exponents ζ_S were estimated to be 1.66 ± 0.06 and 1.48 ± 0.13 for the cluster area and cluster total rain rate, respectively. The two exponents were further found to be related via the expected total rain rate given a cluster area. These results suggest that convection over the tropical oceans is organized into rain clusters with universal scaling properties. They are also related through a simple scaling relation consistent with classical self-organized critical phenomena. The results from this study suggest that mesoscale rain clusters tend to grow by increasing in size and intensity, while larger clusters tend to grow by self-organizing without intensification.

Mots clés: tropical rain clusters; self-organized criticality

Domaines: Planète et Univers [physics]

C. -K. Teo, H. -N. Huynh, T. -Y. Koh, K. K. W. Cheung, B. Legras, et al.. The universal scaling characteristics of tropical oceanic rain clusters. Journal of Geophysical Research: Atmospheres, 2017, 122, pp.5582-5599. ⟨10.1002/2016JD025921⟩. ⟨insu-03727063⟩