Thermal Structure and Dynamics of Saturn's Northern Springtime Disturbance

Science (2011) 1-5

LN Fletcher, BE Hesman, PGJ Irwin, KH Baines, TW Momary, A Sanchez-Lavega, F Michael Flasar, PL Read, GS Orton, A Simon-Miller, R Hueso, GL Bjoraker, A Mamoutkine, T Del Rio-Gaztelurrutia, JM Gomez, B Buratti, RN Clark, PD Nicholson, C Sotin

Generation of inertia-gravity waves in the rotating thermal annulus by a localised boundary layer instability

Geophys. Astrophys. Fluid Dyn. Taylor & Francis Ltd 105 (2011) 161-181

TNL Jacoby, PL Read, PD Williams, RMB Young

Waves with periods shorter than the inertial period exist in the atmosphere (as inertia-gravity waves) and in the oceans (as Poincare and internal gravity waves). Such waves owe their origin to various mechanisms, but of particular interest are those arising either from local secondary instabilities or spontaneous emission due to loss of balance. These phenomena have been studied in the laboratory, both in the mechanically-forced and the thermally-forced rotating annulus. Their generation mechanisms, especially in the latter system, have not yet been fully understood, however. Here we examine short period waves in a numerical model of the rotating thermal annulus, and show how the results are consistent with those from earlier laboratory experiments. We then show how these waves are consistent with being inertia-gravity waves generated by a localised instability within the thermal boundary layer, the location of which is determined by regions of strong shear and downwelling at certain points within a large-scale baroclinic wave flow. The resulting instability launches small-scale inertia-gravity waves into the geostrophic interior of the flow. Their behaviour is captured in fully nonlinear numerical simulations in a finite-difference, 3D Boussinesq Navier-Stokes model. Such a mechanism has many similarities with those responsible for launching small- and meso-scale inertia-gravity waves in the atmosphere from fronts and local convection.

Infrared Radiation and Planetary Temperature


RT Pierrehumbert

Erratum to "Flow transitions resembling bifurcations of the logistic map in simulations of the baroclinic rotating annulus" [Physica D 237 (2008) 2251-2262] (DOI:10.1016/j.physd.2008.02.014)

Physica D: Nonlinear Phenomena (2011)

RMB Young, PL Read

Infrared radiation and planetary temperature

PHYSICS TODAY 64 (2011) 33-38

RT Pierrehumbert



RT Pierrehumbert

Principles of Planetary Climate

Cambridge University Press, 2010

RT Pierrehumbert

This book introduces the reader to all the basic physical building blocks of climate needed to understand the present and past climate of Earth, the climates of Solar System planets, and the climates of extrasolar planets.

Assessing atmospheric predictability on Mars using numerical weather prediction and data assimilation


P Rogberg, PL Read, SR Lewis, L Montabone

Synchronization in climate dynamics and other extended systems

Understanding Complex Systems 2010 (2010) 153-176

PL Read, AA Castrejón-Pita

Synchronization is now well established as representing coherent behaviour between two or more otherwise autonomous nonlinear systems subject to some degree of coupling. Such behaviour has mainly been studied to date, however, in relatively low-dimensional discrete systems or networks. But the possibility of similar kinds of behaviour in continuous or extended spatiotemporal systems has many potential practical implications, especially in various areas of geophysics. We review here a range of cyclically varying phenomena within the Earth's climate system for which there may be some evidence or indication of the possibility of synchronized behaviour, albeit perhaps imperfect or highly intermittent. The exploitation of this approach is still at a relatively early stage within climate science and dynamics, in which the climate system is regarded as a hierarchy of many coupled sub-systems with complex nonlinear feedbacks and forcings. The possibility of synchronization between climate oscillations (global or local) and a predictable external forcing raises important questions of how models of such phenomena can be validated and verified, since the resulting response may be relatively insensitive to the details of the model being synchronized. The use of laboratory analogues may therefore have an important role to play in the study of natural systems that can only be observed and for which controlled experiments are impossible. We go on to demonstrate that synchronization can be observed in the laboratory, even in weakly coupled fluid dynamical systems that may serve as direct analogues of the behaviour of major components of the Earth's climate system. The potential implications and observability of these effects in the long-term climate variability of the Earth is further discussed. © 2010 Springer-Verlag Berlin Heidelberg.

Testing the limits of quasi-geostrophic theory: application to observed laboratory flows outside the quasi-geostrophic regime


PD Williams, PL Read, TWN Haine

Synchronization in a pair of thermally coupled rotating baroclinic annuli: understanding atmospheric teleconnections in the laboratory.

Phys Rev Lett 104 (2010) 204501-

AA Castrejón-Pita, PL Read

Synchronization phenomena in a fluid dynamical analogue of atmospheric circulation is studied experimentally by investigating the dynamics of a pair of thermally coupled, rotating baroclinic annulus systems. The coupling between the systems is in the well-known master-slave configuration in both periodic and chaotic regimes. Synchronization tools such as phase dynamics analysis are used to study the dynamics of the coupled system and demonstrate phase synchronization and imperfect phase synchronization, depending upon the coupling strength and parameter mismatch.

Saturn's emitted power

Journal of Geophysical Research E: Planets 115 (2010)

L Li, BJ Conrath, PJ Gierasch, RK Achterberg, CA Nixon, AA Simon-Miller, FM Flasar, D Banfield, KH Baines, RA West, AP Ingersoll, AR Vasavada, AD Del Genio, CC Porco, AA Mamoutkine, ME Segura, GL Bjoraker, GS Orton, LN Fletcher, PGJ Irwin, PL Read

Long-term (2004-2009) on-orbit observations by Cassini Composite Infrared Spectrometer are analyzed to precisely measure Saturn's emitted power and its meridional distribution. Our evaluations suggest that the average global emitted power is 4.952 ± 0.035 W m-2 during the period of 2004-2009. The corresponding effective temperature is 96.67 ± 0.17 K. The emitted power is 16.6% higher in the Southern Hemisphere than in the Northern Hemisphere. From 2005 to 2009, the global mean emitted power and effective temperature decreased by ∼2% and ∼0.5%, respectively. Our study further reveals the interannual variability of emitted power and effective temperature between the epoch of Voyager (∼1 Saturn year ago) and the current epoch of Cassini, suggesting changes in the cloud opacity from year to year on Saturn. The seasonal and interannual variability of emitted power implies that the energy balance and internal heat are also varying. Copyright © 2010 by the American Geophysical Union.

The Importance of Ice Vertical Resolution for Snowball Climate and Deglaciation

JOURNAL OF CLIMATE 23 (2010) 6100-6109

DS Abbot, I Eisenman, RT Pierrehumbert

Evidence for Climate Change on Mars

in Solar System Update, Springer (2010) 135-

SR Lewis, PL Read

This book, the first in a series of forthcoming volumes, consists of topical and timely reviews of a number of carefully selected topics in solar systemn science.

Effectiveness of stirring measures in an axisymmetric rotating annulus flow


RJ Keane, PL Read, GP King

Element cycling and the evolution of the Earth System


Y Godderis, Y Donnadieu, JZ Williams, C Roelandt, J Schott, D Pollard, RT Pierrehumbert, S Brantley

Structure and dynamics of the Martian lower and middle atmosphere as observed by the Mars Climate Sounder: Seasonal variations in zonal mean temperature, dust, and water ice aerosols


DJ McCleese, NG Heavens, JT Schofield, WA Abdou, JL Bandfield, SB Calcutt, PGJ Irwin, DM Kass, A Kleinbohl, SR Lewis, DA Paige, PL Read, MI Richardson, JH Shirley, FW Taylor, N Teanby, RW Zurek

Global gyrokinetic ITG turbulence simulations of MAST plasmas

37th EPS Conference on Plasma Physics 2010, EPS 2010 1 (2010) 521-524

S Saarelma, A Bottino, J Candy, G Colyer, A Field, W Gutenfelder, P Hill, A Peeters, CM Roach

Structure and dynamics of the Martian lower and middle atmosphere as observed by the Mars Climate Sounder: Seasonal variations in zonal mean temperature, dust, and water ice aerosols

Journal of Geophysical Research E: Planets 115 (2010)

DJ McCleese, NG Heavens, JT Schofield, WA Abdou, JL Bandfield, SB Calcutt, PGJ Irwin, DM Kass, A Kleinböhl, SR Lewis, DA Paige, PL Read, MI Richardson, JH Shirley, FW Taylor, N Teanby, RW Zurek

The first Martian year and a half of observations by the Mars Climate Sounder aboard the Mars Reconnaissance Orbiter has revealed new details of the thermal structure and distributions of dust and water ice in the atmosphere. The Martian atmosphere is shown in the observations by the Mars Climate Sounder to vary seasonally between two modes: a symmetrical equinoctial structure with middle atmosphere polar warming and a solstitial structure with an intense middle atmosphere polar warming overlying a deep winter polar vortex. The dust distribution, in particular, is more complex than appreciated before the advent of these high (∼5 km) vertical resolution observations, which extend from near the surface to above 80 km and yield 13 dayside and 13 nightside pole-to-pole cross sections each day. Among the new features noted is a persistent maximum in dust mass mixing ratio at 15-25 km above the surface (at least on the nightside) during northern spring and summer. The water ice distribution is very sensitive to the diurnal and seasonal variation of temperature and is a good tracer of the vertically propagating tide. Copyright 2010 by the American Geophysical Union.

Geophysical flows as dynamical systems: the influence of Hide's experiments

ASTRONOMY & GEOPHYSICS 51 (2010) 28-35

M Ghil, PL Read, LA Smith