Benchmarking in a rotating annulus: a comparative experimental and numerical study of baroclinic wave dynamics

Abstract

The differentially heated rotating annulus is a widely studied tabletop-size laboratory model of the general mid-latitude atmospheric circulation. The two most relevant factors of cyclogenesis, namely rotation and meridional temperature gradient are quite well captured in this simple arrangement. The radial temperature difference in the cylindrical tank and its rotation rate can be set so that the isothermal surfaces in the bulk tilt, leading to the formation of baroclinic waves. The signatures of these waves at the free water surface have been analyzed via infrared thermography in a wide range of rotation rates (keeping the radial temperature difference constant) and under different initial conditions. In parallel to the laboratory experiments, five groups of the MetStröm collaboration have conducted numerical simulations in the same parameter regime using different approaches and solvers, and applying different initial conditions and perturbations. The experimentally and numerically obtained baroclinic wave patterns have been evaluated and compared in terms of their dominant wave modes, spatio-temporal variance properties and drift rates. Thus certain "benchmarks" have been created that can later be used as test cases for atmospheric numerical model validation.

Spontaneous inertia–gravity wave emission in the differentially heated rotating annulus experiment

“…Hence, this system is well suited to study the dynamics observed in atmospheric baroclinic waves at midlatitudes. Various studies were conducted to investigate baroclinic-wave life cycles and the corresponding jet-front system in the rotating annulus (Früh & Read 1997;Sitte & Egbers 2000;von Larcher & Egbers 2005;Harlander et al 2012;Vincze et al 2014). More recently, the annulus has also been used to examine the generation and propagation of IGWs.…”

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

“…It has also proved valuable as a tractable 'test bed' within which to test numerical codes and methods (Harlander et al 2011;Vincze et al 2015) as well as to benchmark statistical-dynamical analysis methods in widespread use in meteorology, such as data assimilation (Young and Read 2013). Moreover, it is even inspiring new experiments for studying non-terrestrial planetary atmosphere dynamics in the laboratory (Read et al 2015;Yadav et al 2016).…”

Temperature fluctuations in a changing climate: an ensemble-based experimental approach

“…19. The temperature records were obtained using an ALMEMO temperature sensor array of NiCr sensors with a relative resolution of 0.05 K and 1 Hz sampling rate.…”