Atmosphere Ocean Science Colloquium

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Physical understanding of tropical precipitation distribution and convective organization

Speaker: Ziwei Li, NYU

Location: Online

Date: Wednesday, March 9, 2022, 3:30 p.m.

Synopsis:

Tropical precipitation is responsible for regulating the global circulation and the Earth’s energy budget, but many aspects such as the power-law distribution of precipitation clusters and its relation to convective self-aggregation remain poorly understood. In this talk, I will first propose a viewpoint that regards precipitation clusters as manifestations of thresholded islands on a rough column-water vapor (CWV) topography, much like the islands on the Earth’s relief. This allows us to apply statistical topography theories to explain why tropical precipitation clusters are power-law distributed and give quantitative expressions of the power-law exponents. Secondly, I will present a physics-informed conceptual model for tropical convective organization. The model is faithful in simulating self-aggregation in that it shows a domain-size dependence of aggregation found in many prior works, and its CMSE power spectrum is close to that of a cloud-permitting simulation. Through the conceptual model’s equation, I show that the domain-size dependence of self-aggregation is due to competing effects from vertical and horizontal advection, and that the CMSE power spectrum is due to the combination of temporal red noise and diffusive horizontal advection.