Publications by Peter Read

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


H Scolan, PL Read

Phase synchronization of baroclinic waves in a differentially heated rotating annulus experiment subject to periodic forcing with a variable duty cycle.

Chaos (Woodbury, N.Y.) 27 (2017) 127001-

PL Read, X Morice-Atkinson, EJ Allen, AA Castrejón-Pita

A series of laboratory experiments in a thermally driven, rotating fluid annulus are presented that investigate the onset and characteristics of phase synchronization and frequency entrainment between the intrinsic, chaotic, oscillatory amplitude modulation of travelling baroclinic waves and a periodic modulation of the (axisymmetric) thermal boundary conditions, subject to time-dependent coupling. The time-dependence is in the form of a prescribed duty cycle in which the periodic forcing of the boundary conditions is applied for only a fraction δ of each oscillation. For the rest of the oscillation, the boundary conditions are held fixed. Two profiles of forcing were investigated that capture different parts of the sinusoidal variation and δ was varied over the range 0.1≤δ≤1. Reducing δ was found to act in a similar way to a reduction in a constant coupling coefficient in reducing the width of the interval in forcing frequency or period over which complete synchronization was observed (the "Arnol'd tongue") with respect to the detuning, although for the strongest pulse-like forcing profile some degree of synchronization was discernible even at δ=0.1. Complete phase synchronization was obtained within the Arnol'd tongue itself, although the strength of the amplitude modulation of the baroclinic wave was not significantly affected. These experiments demonstrate a possible mechanism for intraseasonal and/or interannual "teleconnections" within the climate system of the Earth and other planets that does not rely on Rossby wave propagation across the planet along great circles.

Regimes of Axisymmetric Flow and Scaling Laws in a Rotating Annulus with Local Convective Forcing

Fluids 2 (2017) 41-41

S Wright, S Su, H Scolan, R Young, P Read

Forward and inverse kinetic energy cascades in Jupiter's turbulent weather layer

NATURE PHYSICS 13 (2017) 1135-+

RMB Young, PL Read

Ertel potential vorticity versus Bernoulli streamfunction on Mars


TE Dowling, ME Bradley, J Du, SR Lewis, PL Read

An experimental investigation of blocking by partial barriers in a rotating baroclinic annulus

Geophysical and Astrophysical Fluid Dynamics (2017) 1-33

SD Marshall, PL Read

© 2017 Informa UK Limited, trading as Taylor & Francis Group We present a series of experimental investigations in which a differentially-heated annulus was used to investigate the effects of topography on rotating, stratified flows with similarities to the Earth’s atmospheric or oceanic circulation. In particular, we compare and investigate blocking effects via partial mechanical barriers to previous experiments by the authors utilising azimuthally-periodic topography. The mechanical obstacle used was an isolated ridge, forming a partial barrier, employed to study the difference between partially blocked and fully unblocked flow. The topography was found to lead to the formation of bottom-trapped waves, as well as impacting the circulation at a level much higher than the top of the ridge. This produced a unique flow structure when the drifting flow and the topography interacted in the form of an “interference” regime at low Taylor number, but forming an erratic “irregular” regime at higher Taylor number. The results also showed evidence of resonant wave-triads, similar to those noted with periodic wavenumber-3 topography by Marshall and Read (Geophys. Astrophys. Fluid Dyn., 2015, 109), though the component wavenumbers of the wave-triads and their impact on the flow were found to depend on the topography in question. With periodic topography, wave-triads were found to occur between both the baroclinic and barotropic components of the zonal wavenumber-3 mode and the wavenumber-6 baroclinic component, whereas with the partial barrier two nonlinear resonant wave-triads were noted, each sharing a common wavenumber-1 mode.

Synchronisation of the equatorial QBO by the annual cycle in tropical upwelling in a warming climate


K Rajendran, IM Moroz, PL Read, SM Osprey

Global energy budgets and "Trenberth diagrams' for the climates of terrestrial and gas giant planets


PL Read, J Barstow, B Charnay, S Chelvaniththilan, PGJ Irwin, S Knight, S Lebonnois, SR Lewis, J Mendonca, L Montabone

Spectral analysis of Uranus' 2014 bright storm with VLT/SINFONI

ICARUS 264 (2016) 72-89

PGJ Irwin, LN Fletcher, PL Read, D Tice, I de Pater, GS Orton, NA Teanby, GR Davis

A regime diagram for ocean geostrophic turbulence


A Klocker, DP Marshall, SR Keating, PL Read

Exploring the Venus global super-rotation using a comprehensive general circulation model


JM Mendonca, PL Read

The solsticial pause on Mars: 1. A planetary wave reanalysis

ICARUS 264 (2016) 456-464

SR Lewis, DP Mulholland, PL Read, L Montabone, RJ Wilson, MD Smith

The solsticial pause on Mars: 2 modelling and investigation of causes

ICARUS 264 (2016) 465-477

DP Mulholland, SR Lewis, PL Read, J-B Madeleine, F Forget

Predictability of the thermally driven laboratory rotating annulus


RMB Young, PL Read

An experimental study of multiple zonal jet formation in rotating, thermally driven convective flows on a topographic beta-plane

PHYSICS OF FLUIDS 27 (2015) ARTN 085111

PL Read, TNL Jacoby, PHT Rogberg, RD Wordsworth, YH Yamazaki, K Miki-Yamazaki, RMB Young, J Sommeria, H Didelle, S Viboud

A new, fast and flexible radiative transfer method for Venus general circulation models


JM Mendonca, PL Read, CF Wilson, C Lee

An experimental investigation into topographic resonance in a baroclinic rotating annulus


SD Marshall, PL Read

The solsticial pause on Mars: 2 modelling and investigation of causes

Icarus 264 (2015) 465-477

DP Mulholland, SR Lewis, PL Read, JB Madeleine, F Forget

© 2015 Elsevier Inc. The martian solsticial pause, presented in a companion paper (. Lewis et al., 2016), was investigated further through a series of model runs using the UK version of the LMD/UK Mars Global Climate Model. It was found that the pause could not be adequately reproduced if radiatively active water ice clouds were omitted from the model. When clouds were used, along with a realistic time-dependent dust opacity distribution, a substantial minimum in near-surface transient eddy activity formed around solstice in both hemispheres. The net effect of the clouds in the model is, by altering the thermal structure of the atmosphere, to decrease the vertical shear of the westerly jet near the surface around solstice, and thus reduce baroclinic growth rates. A similar effect was seen under conditions of large dust loading, implying that northern midlatitude eddy activity will tend to become suppressed after a period of intense flushing storm formation around the northern cap edge. Suppression of baroclinic eddy generation by the barotropic component of the flow and via diabatic eddy dissipation were also investigated as possible mechanisms leading to the formation of the solsticial pause but were found not to make major contributions. Zonal variations in topography were found to be important, as their presence results in weakened transient eddies around winter solstice in both hemispheres, through modification of the near-surface flow. The zonal topographic asymmetry appears to be the primary reason for the weakness of eddy activity in the southern hemisphere relative to the northern hemisphere, and the ultimate cause of the solsticial pause in both hemispheres. The meridional topographic gradient was found to exert a much weaker influence on near-surface transient eddies.

A Lorenz/Boer energy budget for the atmosphere of Mars from a "reanalysis" of spacecraft observations


F Tabataba-Vakili, PL Read, SR Lewis, L Montabone, T Ruan, Y Wang, A Valeanu, RMB Young

Polar vortices on Earth and Mars: A comparative study of the climatology and variability from reanalyses.

Quarterly journal of the Royal Meteorological Society. Royal Meteorological Society (Great Britain) 141 (2015) 550-562

DM Mitchell, L Montabone, S Thomson, PL Read

Polar vortices on Mars provide case-studies to aid understanding of geophysical vortex dynamics and may help to resolve long-standing issues regarding polar vortices on Earth. Due to the recent development of the first publicly available Martian reanalysis dataset (MACDA), for the first time we are able to characterise thoroughly the structure and evolution of the Martian polar vortices, and hence perform a systematic comparison with the polar vortices on Earth. The winter atmospheric circulations of the two planets are compared, with a specific focus on the structure and evolution of the polar vortices. The Martian residual meridional overturning circulation is found to be very similar to the stratospheric residual circulation on Earth during winter. While on Earth this residual circulation is very different from the Eulerian circulation, on Mars it is found to be very similar. Unlike on Earth, it is found that the Martian polar vortices are annular, and that the Northern Hemisphere vortex is far stronger than its southern counterpart. While winter hemisphere differences in vortex strength are also reported on Earth, the contrast is not as large. Distinctions between the two planets are also apparent in terms of the climatological vertical structure of the vortices, in that the Martian polar vortices are observed to decrease in size at higher altitudes, whereas on Earth the opposite is observed. Finally, it is found that the Martian vortices are less variable through the winter than on Earth, especially in terms of the vortex geometry. During one particular major regional dust storm on Mars (Martian year 26), an equatorward displacement of the vortex is observed, sharing some qualitative characteristics of sudden stratospheric warmings on Earth.