Tuesday, 14 June - Final ICTP/UniTN/UniAQ Joint Seminar on Weather and Climate

[Earth System Physics Section]

*ICTP/UniTN/UniAQ Joint International Seminar Series
on Weather and Climate: From Fundamentals to Applications*

Tuesday, 14 June at 15:30 CET

**Speaker: *Caroline Muller*
Assistant Professor, Institute of Science and Technology (IST)
Klosterneuburg, Austria

Title: How Do Ocean Temperature Anomalies Favor or Disfavor the 
Aggregation of Deep Convective Clouds?

Abstract

Convective organization at mesoscales (hundreds of kilometres) is 
ubiquitous in the tropics, but the physical processes behind it are 
still poorly understood. Organization can be forced by the large scales, 
such as surface temperature gradients. But convective organization can 
also arise from internal feedbacks, such as "self-aggregation" 
feedbacks. Self-aggregation refers to the spectacular ability of deep 
clouds to spontaneously cluster in space despite spatially homogeneous 
conditions and no large-scale forcing, in high-resolution 
cloud-resolving models (CRMs).Because of the idealized settings in which 
self-aggregation has been studied (typically radiative-convective 
equilibrium (RCE) over homogeneous sea-surface temperature (SST)), its 
relevance to the real tropics is debated. In this presentation, we will 
investigate the impact of removing some of these idealizations on the 
aggregation process. Specifically, we will investigate the impact of 
inhomogeneous SSTs on convective aggregation.

In a first step, we will investigate how an idealized warm circular SST 
anomaly, referred to as "hot-spot", helps organize convection, and how 
self-aggregation feedbacks modulate this organization. The presence of a 
hot-spot significantly accelerates aggregation, particularly for larger 
domains and warmer/larger hot-spots, and extends the range of SSTs for 
which aggregation occurs. In that case, the aggregation onset results 
from a large-scale circulation induced by the hot-spot. In a second 
step, we will investigate the interaction of aggregation with an 
interactive surface (local SST evolving according to the surface energy 
budget). The results will be interpreted in light of a simple model for 
the boundary layer circulation.



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