Relationship Between Precipitation Extremes and Convective Organization Inferred From Satellite Observations.

Addisu Gezahegn Semie,Sandrine Bony

doi:10.1029/2019gl086927

Abstract

Convective organization has the potential to impact the strength of precipitation extremes, but numerical models disagree about this influence. This study uses satellite observations to investigate the link between the mesoscale organization of deep convection and precipitation extremes in the Tropics. Extremes in domain‐averaged precipitation are found mostly over the western Pacific and Indian Ocean warm pools, and they primarily depend on the number of deep convective entities within the domain. On the other hand, extremes in local precipitation are found primarily over land, and they increase with the degree of convective organization. Therefore, this observational study shows evidence for a modulation of the strength of tropical precipitation extremes by the spatial organization of deep convection, especially over land.

Highlights

Organized deep convection is ubiquitous in the Tropics and it occurs over a wide range of spatial and temporal scales
We use satellite observations to investigate this issue, and we show strong evidence that the occurrence of extreme precipitation over tropical land depends on the degree of mesoscale organization of deep convection
This study analyzes how mean precipitation and extreme precipitation relate to the number of deep convective entities (N) and to the spatial organization of deep convection (Iorg) at the scale of 10◦ × 10◦ domains in the tropics

Summary

Introduction

Organized deep convection is ubiquitous in the Tropics and it occurs over a wide range of spatial and temporal scales. Mesoscale organization and large cloud clusters, that occur on scales of hundred to thousand kilometers (Houze, 2014; Lilly & Gal-Chen, 2013), include short-lived aggregates of thunderstorms, well-organized squall lines, and long-lived tropical storms and hurricanes. Most extreme events such as heavy rain, flash floods, and severe weather are associated with organized convective systems (Mathon et al, 2002; Nesbitt et al, 2006).

Data and Method

Convective Organization Index

Link Between Precipitation Extremes and Convective Organization

Findings

Conclusion and Discussion