General Circulation of Planetary Atmospheres

Abstract

In engineering and the applied sciences, the term "model" is typically used to denote a device or concept that imitates the behavior of a physical system as closely as possible, but on a different (usually smaller) scale, possibly with some simplifications. The aim of such a model is normally to evaluate the performance of such a system for reasons connected with its exploitation for economic, social, military, or other purposes. In the context of the atmosphere or oceans, numerical weather and climate prediction models clearly fall into this category. Such models are extremely complicated entities that seek to represent the topography, composition, radiative transfer, and dynamics of the atmosphere, oceans, and surface in great detail. As a result, it is generally impossible to comprehend fully the complex interactions of physical processes and scales of motion that occur within any given simulation. The success of such models can only be judged by the accuracy of their predictions as directly verified (in the case of numerical weather prediction) against subsequent observations and measurements. Similar models used for climate prediction, however, are often comparable in complexity to those used for weather prediction but are frequently used as tools in attempts to address questions of economic, social, or political importance (e.g., concerning the impact of increasing anthropogenic greenhouse gas emissions) for which little or no verifying data may be available.In formulating such models and interpreting their results, it is necessary to make use of a different class of

A rotating annulus driven by localized convective forcing: a new atmosphere-like experiment

“…Following Hignett et al (1981), Read (1986), King et al (2009) and Read et al (2014), we anticipate that a significant parameter associated with the thermal structure of the system will be the squared ratio of the characteristic length scales of the buoyancy-driven thermal boundary layer (without rotation) and the Ekman layers. Assuming that the thermal boundary layer length scale ℓ T = H/(2Nu) ∼ HRa −γ , where Nu is the Nusselt number characterising the efficiency of the heat transfer in the fluid in comparison with pure conduction Ra is the Rayleigh number Rayleigh number (Eq.…”

“…Shraiman and Siggia (1990) and review by Chillà and Schumacher (2012)]. Errors bars shown are illustrating standard deviation on the averaging period at a given rotating rate When background rotation is significant, two regimes were identified as a function of the rotation rate and classified as a function of P, the ratio of (non-rotating) thermal boundary layer to Ekman boundary layer thicknesses (Read 1986;Read et al 2014;Wright et al 2017). An (r, z) cross section of the temperature field from axisymmetric numerical simulations by Wright et al (2017) of the similar configuration as the current experiment is illustrated in Fig.…”

“…1a) originally proposed by Hide, has proved to be a prolific and productive analogue of many features of the atmospheric circulation (Hide 1958;Fowlis and Hide 1965;Hide et al 1977;Read et al 2014). By combining only the three essential physical ingredients forcing the atmosphere, i.e., gravity, rotation, and differential heating, the 'classical' thermally driven rotating annulus setup provides an experimental configuration that enables both large-scale overturning circulations and baroclinic instabilities to be studied and explored.…”

New Laboratory Experiments to Study the Large-Scale Circulation and Climate Dynamics

“…The work until the mid-1970s is summarized in a review article by [9] and until the 1990s in a book chapter by [10]. To our knowledge the most recent review that also nicely embeds the annulus experiments in current work on the general atmospheric circulation is given by [11]. Insightful are further articles commemorating the 80th birthday of Raymond Hide [12,13].…”

Predictability of the thermally driven laboratory rotating annulus

“…Lorenz (1975) defined two kinds of predictability: the first concerns the evolution of a system from initial conditions (the 'weather' problem), and the second the predicted behaviour given certain boundary conditions (the 'climate' problem). The second kind is well characterised in some regions of parameter space for the rotating annulus (Hide and Mason, 1975;Read et al, 1992;Früh and Read, 1997;Read et al, 2015), but the first kind has not previously been studied in much depth. Limited previous work includes using a radial basis function model to measure ιshadowing times from experimental temperature data (Gilmour, 1998), and calculations of the Lyapunov exponents for various annulus flow regimes from experimental time series (Read et al, 1992;Früh and Read, 1997), but these have only limited usefulness for characterizing the general predictability of complex systems.…”