A shallow layer laboratory model of large-scale atmospheric circulation

TL;DR

This paper introduces a novel shallow layer laboratory model simulating large-scale atmospheric circulation, capturing complex, non-periodic wave behaviors and flow regimes akin to real atmospheric dynamics.

Contribution

The study presents a new laboratory model with shifted heating sources and low-viscosity fluid to better mimic atmospheric flows and their complex temporal behaviors.

Findings

Flow transitions from Hadley-like to baroclinic wave regimes.

Regularization of baroclinic waves with decreasing thermal Rossby number.

Presence of non-periodic, evolving baroclinic modes.

Abstract

A new shallow layer laboratory model of global atmosphere circulation is realized. The shallow rotating cylindrical layer of fluid with the localized heater at the bottom periphery and localized cooler in the central part of the upper boundary is considered. The rim heater imitates the equator heating and disc cooler -- the north pole cooling. The rim heater is intentionally shifted from the sidewall to decrease the influence of the no-slip vertical boundaries and provide anticyclonic-cyclonic motion in the upper layer, imitating the formation of large-scale zonal flows (easterlies and westerlies) in the low latitudes. The low-viscous silicon oil is used instead of water to avoid complex effects provided by the formation of a thin film of a surface-active substance on the open surface. The flow transforms from the Hadley-like regime to the baroclinic wave regime through transitional states. The decrease in the thermal Rossby number for the fixed value of Taylor number results in the regularization of the baroclinic waves. The main difference between presented and classical annulus configurations is the absence of the steady waves. All wave regimes, even with regular wave structures, are characterized by strong non-periodic fluctuations. The observed baroclinic wave structures are a combination of temporarily evolving different baroclinic modes. The presented model provides the formation of atmospheric-like flows, characterized by complex temporal behaviour and can serve as an efficient tool for studying different aspects of global atmospheric circulation.