General Circulation of Planetary Atmospheres: Insights from Rotating Annulus and Related Experiments

Modeling Atmospheric and Oceanic Flows: Insights from Laboratory Experiments and Numerical Simulations John Wiley & Sons Ltd. (2015) 9-44

PL Read, EP Perez, IM Moroz, RMB Young

General Circulation of Planetary Atmospheres: Insights from Rotating Annulus and Related Experiments

in Modeling Atmospheric and Oceanic Flows: Insights from Laboratory Experiments and Numerical Simulations, 9781118855935 (2014) 7-44

PL Read, EP Pérez, IM Moroz, RMB Young

© 2015 American Geophysical Union. This chapter focuses on the "classical" thermally driven, rotating annulus system. It reviews the current state of understanding of the rich and diverse range of flow regimes that may be exhibited in thermal annulus experiments from the viewpoint of experimental observation, numerical simulation, and fundamental theory. This includes interpretation of various empirical experimental observations in relation to both linear and weakly nonlinear baroclinic instability theory. The chapter then examines how heat is transported within the baroclinic annulus across the full range of control parameters, associated with both the boundary layer circulation and baroclinically unstable eddies. It considers the overall role of annulus experiments in the laboratory in continuing to advance understanding of the global circulation of planetary atmospheres and oceans, reviewing the current state of research on delineating circulation regimes obtained in large-scale circulation models in direct comparison with the sequences of flow regimes and transitions in the laboratory.

The physics of Martian weather and climate: a review.

Reports on progress in physics. Physical Society (Great Britain) 78 (2015) 125901-

PL Read, SR Lewis, DP Mulholland

The planet Mars hosts an atmosphere that is perhaps the closest in terms of its meteorology and climate to that of the Earth. But Mars differs from Earth in its greater distance from the Sun, its smaller size, its lack of liquid oceans and its thinner atmosphere, composed mainly of CO(2). These factors give Mars a rather different climate to that of the Earth. In this article we review various aspects of the martian climate system from a physicist's viewpoint, focusing on the processes that control the martian environment and comparing these with corresponding processes on Earth. These include the radiative and thermodynamical processes that determine the surface temperature and vertical structure of the atmosphere, the fluid dynamics of its atmospheric motions, and the key cycles of mineral dust and volatile transport. In many ways, the climate of Mars is as complicated and diverse as that of the Earth, with complex nonlinear feedbacks that affect its response to variations in external forcing. Recent work has shown that the martian climate is anything but static, but is almost certainly in a continual state of transient response to slowly varying insolation associated with cyclic variations in its orbit and rotation. We conclude with a discussion of the physical processes underlying these long- term climate variations on Mars, and an overview of some of the most intriguing outstanding problems that should be a focus for future observational and theoretical studies.

A sea change in exoplanet climate models?

Astrobiology 14 (2014) 627-628

PL Read

On the stirring properties of the thermally-driven rotating annulus


RJ Keane, PL Read, GP King

A simple carbon cycle representation for economic and policy analyses

CLIMATIC CHANGE 126 (2014) 319-335

MJ Glotter, RT Pierrehumbert, JW Elliott, NJ Matteson, EJ Moyer

Short-Lived Climate Pollution


RT Pierrehumbert



R Wordsworth, R Pierrehumbert

Characterizing exoplanets

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372 (2014)

S Miller, A Coustenis, P Read, J Tennyson

Cassini observations reveal a regime of zonostrophic macroturbulence on Jupiter

Icarus 229 (2014) 295-320

B Galperin, RMB Young, S Sukoriansky, N Dikovskaya, PL Read, AJ Lancaster, D Armstrong

In December 2000, the Cassini fly-by near Jupiter delivered high-resolution images of Jupiter's clouds over the entire planet in a band between 50°N and 50°S. Three daily-averaged two-dimensional velocity snapshots extracted from these images are used to perform spectral analysis of jovian atmospheric macroturbulence. A similar analysis is also performed on alternative data documented by Choi and Showman (Choi, D., Showman, A. [2011]. Icarus 216, 597-609), based on a different method of image processing. The inter-comparison of the products of both analyses ensures a better constraint of the spectral estimates. Both analyses reveal strong anisotropy of the kinetic energy spectrum. The zonal spectrum is very steep and most of the kinetic energy resides in slowly evolving, alternating zonal (west-east) jets, while the non-zonal, or residual spectrum obeys the Kolmogorov-Kraichnan law specific to two-dimensional turbulence in the range of the inverse energy cascade. The spectral data is used to estimate the inverse cascade rate {small element of} and the zonostrophy index R β for the first time. Although both datasets yield somewhat different values of {small element of}, it is estimated to be in the range 0.5-1.0×10 -5 m 2 s -3 . The ensuing values of R β ≳5 belong well in the range of zonostrophic turbulence whose threshold corresponds to R β ≃2.5. We infer that the large-scale circulation is maintained by an anisotropic inverse energy cascade. The removal of the Great Red Spot from both datasets has no significant effect upon either the spectra or the inverse cascade rate. The spectral data are used to compute the rate of the energy exchange, W, between the non-zonal structures and the large-scale zonal flow. It is found that instantaneous values of W may exceed {small element of} by an order of magnitude. Previous numerical simulations with a barotropic model suggest that W and {small element of} attain comparable values only after averaging of W over a sufficiently long time. Near-instantaneous values of W that have been routinely used to infer the rate of the kinetic energy supply to Jupiter's zonal flow may therefore significantly overestimate {small element of}. This disparity between W and {small element of} may resolve the long-standing conundrum of an unrealistically high rate of energy transfer to the zonal flow. The meridional diffusivity K φ in the regime of zonostrophic turbulence is given by an expression that depends on {small element of}. The value of K φ estimated from the spectra is compared against data from the dispersion of stratospheric gases and debris resulting from the Shoemaker-Levy 9 comet and Wesley asteroid impacts in 1994 and 2009 respectively. Not only is K φ found to be consistent with estimates for both impacts, but the eddy diffusivity found from observations appears to be scale-independent. This behaviour could be a consequence of the interaction between anisotropic turbulence and Rossby waves specific to the regime of zonostrophic macroturbulence. © 2013 Elsevier Inc.

The Mars Analysis Correction Data Assimilation (MACDA) Dataset V1.0


L Montabone, K Marsh, SR Lewis, PL Read, MD Smith, J Holmes, A Spiga, D Lowe, A Pamment



J Peralta, T Imamura, PL Read, D Luz, A Piccialli, MA Lopez-Valverde



J Peralta, T Imamura, PL Read, D Luz, A Piccialli, MA Lopez-Valverde

Simulating the interannual variability of major dust storms on Mars using variable lifting thresholds

Icarus 223 (2013) 344-358

DP Mulholland, PL Read, SR Lewis

The redistribution of a finite amount of martian surface dust during global dust storms and in the intervening periods has been modelled in a dust lifting version of the UK Mars General Circulation Model. When using a constant, uniform threshold in the model's wind stress lifting parameterisation and assuming an unlimited supply of surface dust, multiannual simulations displayed some variability in dust lifting activity from year to year, arising from internal variability manifested in surface wind stress, but dust storms were limited in size and formed within a relatively short seasonal window. Lifting thresholds were then allowed to vary at each model gridpoint, dependent on the rates of emission or deposition of dust. This enhanced interannual variability in dust storm magnitude and timing, such that model storms covered most of the observed ranges in size and initiation date within a single multiannual simulation. Peak storm magnitude in a given year was primarily determined by the availability of surface dust at a number of key sites in the southern hemisphere. The observed global dust storm (GDS) frequency of roughly one in every 3. years was approximately reproduced, but the model failed to generate these GDSs spontaneously in the southern hemisphere, where they have typically been observed to initiate. After several years of simulation, the surface threshold field-a proxy for net change in surface dust density-showed good qualitative agreement with the observed pattern of martian surface dust cover. The model produced a net northward cross-equatorial dust mass flux, which necessitated the addition of an artificial threshold decrease rate in order to allow the continued generation of dust storms over the course of a multiannual simulation. At standard model resolution, for the southward mass flux due to cross-equatorial flushing storms to offset the northward flux due to GDSs on a timescale of ∼3. years would require an increase in the former by a factor of 3-4. Results at higher model resolution and uncertainties in dust vertical profiles mean that quasi-periodic redistribution of dust on such a timescale nevertheless appears to be a plausible explanation for the observed GDS frequency. © 2012 Elsevier Inc.

Experimental signatures of critically balanced turbulence in MAST

Physical Review Letters 110 (2013)

YC Ghim, A Schekochihin, AR Field, IG Abel, M Barnes, G Colyer, SC Cowley, FI Parra, D Dunai, S Zoletnik

Beam emission spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that the turbulence correlation time, the drift time associated with ion temperature or density gradients, the particle (ion) streaming time along the magnetic field, and the magnetic drift time are consistently comparable, suggesting a "critically balanced" turbulence determined by the local equilibrium. The resulting scalings of the poloidal and radial correlation lengths are derived and tested. The nonlinear time inferred from the density fluctuations is longer than the other times; its ratio to the correlation time scales as ν*i-0. 8±0.1, where ν*i=ion  ⠀Šcollision   rate/streaming   rate. This is consistent with turbulent decorrelation being controlled by a zonal component, invisible to the BES, with an amplitude exceeding those of the drift waves by ∼ν*i-0.8. Published by the American Physical Society.

Overview of physics results from MAST towards ITER/DEMO and the MAST Upgrade

NUCLEAR FUSION 53 (2013) ARTN 104008

H Meyer, IG Abel, RJ Akers, A Allan, SY Allan, LC Appel, O Asunta, M Barnes, NC Barratt, N Ben Ayed, JW Bradley, J Canik, P Cahyna, M Cecconello, CD Challis, IT Chapman, D Ciric, G Colyer, NJ Conway, M Cox, BJ Crowley, SC Cowley, G Cunningham, A Danilov, A Darke, MFM De Bock, G De Temmerman, RO Dendy, P Denner, D Dickinson, AY Dnestrovsky, Y Dnestrovsky, MD Driscoll, B Dudson, D Dunai, M Dunstan, P Dura, S Elmore, AR Field, G Fishpool, S Freethy, W Fundamenski, L Garzotti, YC Ghim, KJ Gibson, MP Gryaznevich, J Harrison, E Havlickova, NC Hawkes, WW Heidbrink, TC Hender, E Highcock, D Higgins, P Hill, B Hnat, MJ Hole, J Horacek, DF Howell, K Imada, O Jones, E Kaveeva, D Keeling, A Kirk, M Kocan, RJ Lake, M Lehnen, HJ Leggate, Y Liang, MK Lilley, SW Lisgo, YQ Liu, B Lloyd, GP Maddison, J Mailloux, R Martin, GJ McArdle, KG McClements, B McMillan, C Michael, F Militello, P Molchanov, S Mordijck, T Morgan, AW Morris, DG Muir, E Nardon, V Naulin, G Naylor, AH Nielsen, MR O'Brien, T O'Gorman, S Pamela, FI Parra, A Patel, SD Pinches, MN Price, CM Roach, JR Robinson, M Romanelli, V Rozhansky, S Saarelma, S Sangaroon, A Saveliev, R Scannell, J Seidl, SE Sharapov, AA Schekochihin, V Shevchenko, S Shibaev, D Stork, J Storrs, A Sykes, GJ Tallents, P Tamain, D Taylor, D Temple, N Thomas-Davies, A Thornton, MR Turnyanskiy, M Valovic, RGL Vann, E Verwichte, P Voskoboynikov, G Voss, SEV Warder, HR Wilson, I Wodniak, S Zoletnik, R Zagorski, MAST Team, NBI Team



RD Wordsworth, RT Pierrehumbert

Hot climates, high sensitivity.

Proceedings of the National Academy of Sciences of the United States of America 110 (2013) 14118-14119

RT Pierrehumbert

Hydrogen-nitrogen greenhouse warming in Earth's early atmosphere.

Science (New York, N.Y.) 339 (2013) 64-67

R Wordsworth, R Pierrehumbert

Understanding how Earth has sustained surface liquid water throughout its history remains a key challenge, given that the Sun's luminosity was much lower in the past. Here we show that with an atmospheric composition consistent with the most recent constraints, the early Earth would have been significantly warmed by H(2)-N(2) collision-induced absorption. With two to three times the present-day atmospheric mass of N(2) and a H(2) mixing ratio of 0.1, H(2)-N(2) warming would be sufficient to raise global mean surface temperatures above 0°C under 75% of present-day solar flux, with CO(2) levels only 2 to 25 times the present-day values. Depending on their time of emergence and diversification, early methanogens may have caused global cooling via the conversion of H(2) and CO(2) to CH(4), with potentially observable consequences in the geological record.

Cumulative Carbon and Just Allocation of the Global Carbon Commons

Chicago Journal of International Law 13 (2013) 12

RT Pierrehumbert