Atmosphere Ocean Science Friday Seminar

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Radiation Impacts on Hurricane-Like Vortices in the Conditionally Unstable Atmosphere

Speaker: Mu-Hua Chien, CAOS

Location: Warren Weaver Hall 1314

Date: Friday, October 6, 2023, 4 p.m.

Synopsis:

This research explores the impact of radiative cooling on hurricane-like vortices within the rotating moist Rayleigh–Bénard convection (RMRBC). Within RMRBC scenarios, a rotating Boussinesq atmosphere employs simplified thermodynamics for phase transition, destabilized by a warm, moist lower boundary contrasted by a colder, dryer upper rigid boundary. This setup simulates the atmosphere under a conditionally unstable environment, where unsaturated air parcels remain stable and saturated ones become convectively unstable. In the equilibrium status, hurricane-like vortices serve as heat engines, effectively transporting heat by inhibiting the mixing of dry air parcels.

Radiative cooling destabilizes the lower atmospheric layer, consequently enhancing upward mass and heat transport. This destabilization potentially triggers local instability and a transitional equilibrium regime where structured hurricane-like vortices replaced by disorganized convective plumes. Additionally, radiative cooling increases the work performed by the moist convection, associated with the vertical transport of total water content. Despite an increase in kinetic energy generation in the presence of radiative cooling, thermal efficiency—defined as the ratio of kinetic energy generation rate to available potential energy—experiences a reduction. This reduction is attributed to mixing throughout entire domain, associated with the destabilization at the lower boundary.