Publications


A simplified model of the Martian atmosphere - Part 2: A POD-Galerkin analysis

Nonlinear Processes in Geophysics 12 (2005) 625-642

SG Whitehouse, SR Lewis, IM Moroz, PL Read

In Part I of this study Whitehouse et al. (2005) performed a diagnostic analysis of a simplied model of the Martian atmosphere, in which topography was absent and in which heating was modelled as Newtonian relaxation towards a zonally symmetric equilibrium temperature field. There we derived a reduced-order approximation to the vertical and the horizonal structure of the baroclinically unstable Martian atmosphere, retaining only the barotropic mode and the leading order baroclinic modes. Our objectives in Part II of the study are to incorporate these approximations into a Proper Orthogonal Decomposition-Galerkin expansion of the spherical quasi-geostrophic model in order to derive hierarchies of nonlinear ordinary differential equations for the time-varying coefficients of the spatial structures. Two different vertical truncations are considered, as well as three different norms and 3 different Galerkin truncations. We investigate each in turn, using tools from bifurcation theory, to determine which of the systems most closely resembles the data for which the original diagnostics were performed. © 2005 Author(s). This work is licensed under a Creative Commons License.


A numerical model of the atmosphere of Venus

ADV SPACE RES 36 (2005) 2142-2145

C Lee, SR Lewis, PL Read

A new general circulation model (GCM) of Venus is being developed at Oxford. Venus presents unique numerical and physical challenges because of its thick atmosphere, slow underlying solid body rotation, and super-rotating atmosphere. Preliminary results from a GCM with simplified physical parameterizations are discussed. The current model uses linearized cooling and friction schemes, and spans five decades of pressure (0-90 km). The model is able to demonstrate significant global super-rotation, and although not yet fully realistic, future plans include more detailed representation of the Venusian atmosphere, such as the planetary boundary layer (PBL) scheme. The use of the model is discussed in supporting and interpreting data from future missions to Venus. (c) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.


The atmospheric circulation and dust activity in different orbital epochs on Mars

Icarus 174 (2005) 135-160

PL Read, C E Newman, S R Lewis


Climate dynamics of a hard snowball Earth

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 110 (2005) ARTN D01111

RT Pierrehumbert


The effects of the martian regolith on GCM water cycle simulations

ICARUS 177 (2005) 174-189

HM Bottger, SR Lewis, PL Read, F Forget


From mixing to geostrophy: geostrophic turbulence in atmospheres, oceans, and the laboratory

in Marine Turbulence, Cambridge Univ Pr (2005) 52

PL Read

This 2005 book gives a comprehensive overview of measurement techniques and theories for marine turbulence and mixing processes.


Exploring the Saturn system in the thermal infrared: The composite infrared spectrometer

Space Science Reviews 115 (2005) 169-297

FM Flasar, VG Kunde, MM Abbas, RK Achterberg, P Ade, A Barucci, B Bézard, GL Bjoraker, JC Brasunas, S Calcutt, R Carlson, CJ Césarsky, BJ Conrath, A Coradini, R Courtin, A Coustenis, S Edberg, S Edgington, C Ferrari, T Fouchet, D Gautier, PJ Gierasch, K Grossman, P Irwin, DE Jennings, E Lellouch, AA Mamoutkine, A Marten, JP Meyer, CA Nixon, GS Orton, TC Owen, JC Pearl, R Prangé, F Raulin, PL Read, PN Romani, RE Samuelson, ME Segura, MR Showalter, AA Simon-Miller, MD Smith, JR Spencer, LJ Spilker, FW Taylor

The Composite Infrared Spectrometer (CIRS) is a remote-sensing Fourier Transform Spectrometer (FTS) on the Cassini orbiter that measures thermal radiation over two decades in wavenumber, from 10 to 1400 cm- 1 (1 mm to 7μ m), with a spectral resolution that can be set from 0.5 to 15.5 cm- 1. The far infrared portion of the spectrum (10-600 cm - 1) is measured with a polarizing interferometer having thermopile detectors with a common 4-mrad field of view (FOV). The middle infrared portion is measured with a traditional Michelson interferometer having two focal planes (600-1100 cm- 1, 1100-1400 cm- 1). Each focal plane is composed of a 1× 10 array of HgCdTe detectors, each detector having a 0.3-mrad FOV. CIRS observations will provide three-dimensional maps of temperature, gas composition, and aerosols/condensates of the atmospheres of Titan and Saturn with good vertical and horizontal resolution, from deep in their tropospheres to high in their mesospheres. CIRS's ability to observe atmospheres in the limb-viewing mode (in addition to nadir) offers the opportunity to provide accurate and highly resolved vertical profiles of these atmospheric variables. The ability to observe with high-spectral resolution should facilitate the identification of new constituents. CIRS will also map the thermal and compositional properties of the surfaces of Saturn's icy satellites. It will similarly map Saturn's rings, characterizing their dynamical and spatial structure and constraining theories of their formation and evolution. The combination of broad spectral range, programmable spectral resolution, the small detector fields of view, and an orbiting spacecraft platform will allow CIRS to observe the Saturnian system in the thermal infrared at a level of detail not previously achieved. © 2004 Kluwer Academic Publishers.


A simplified model of the Martian atmosphere - Part 1: A diagnostic analysis

Nonlinear Processes in Geophysics 12 (2005) 603-623

SG Whitehouse, SR Lewis, IM Moroz, PL Read

In this paper we derive a reduced-order approximation to the vertical and horizontal structure of a simplified model of the baroclinically unstable Martian atmosphere. The original model uses the full hydrostatic primitive equations on a sphere, but has only highly simplified schemes to represent the detailed physics of the Martian atmosphere, e.g. forcing towards a plausible zonal mean temperature state using Newtonian cooling. Three different norms are used to monitor energy conversion processes in the model and are then compared. When four vertical modes (the barotropic and first three baroclinic modes) are retained in the reduced-order approximation, the correlation norm captures approximately 90% of the variance, while the kinetic energy and total energy norms capture approximately 83% and 78% of the kinetic and total energy respectively. We show that the leading order Proper Orthogonal Decomposition (POD) modes represent the dominant travelling waves in the baroclinically-unstable, winter hemisphere. In part 2 of our study we will develop a hierarchy of truncated POD-Galerkin expansions of the model equations using up to four vertical modes. © 2005 Author(s). This work is licensed under a Creative Commons License.


Temperatures, Winds, and Composition in the Saturnian System

Science 307 (2005) 1247-1251

FM Flasar, PGJ Irwin, SB Calcutt, R Achterberg, FW Taylor


Hadley circulation and Kelvin wave-induced equatorial jets in the atmospheres of Jupiter and Saturn

Planetary and Space Science 53 (2005) 508-525

Y Yamazaki, P.L. Read, D.R. Skeet


Titan's Atmospheric Temperatures, Winds, and Composition.

Science 308 (2005) 975-978

FW Taylor, Flasar F.M., Achterberg, R.K., Conrath, B.J.


3D balanced winds and dynamics in Jupiter's atmosphere from combined imaging and infrared observations

ADV SPACE RES 36 (2005) 2187-2193

PL Read, PJ Gierasch, BJ Conrath, YH Yamazaki

A series of analyses combining feature-tracking from visible images and infrared sounding observations obtained by Voyager I and 2 are presented for the region surrounding Jupiter's Great Red Spot. By making use of various dynamical balance constraints, fully three-dimensional maps of a number of meteorological variables (such as horizontal wind, isobaric geopotential height and vertical velocity) can be recovered. Such maps are of immense potential value in a variety of studies of atmospheres such as those of the outer planets, and some possible extensions of this approach to ongoing and future spacecraft missions are discussed. (c) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.


On the generation mechanisms of short-scale unbalanced modes in rotating two-layer flows with vertical shear

JOURNAL OF FLUID MECHANICS 528 (2005) 1-22

PD Williams, TWN Haine, PL Read


Interannual variability of Martian dust storms in assimilation of several years of Mars global surveyor observations

ADV SPACE RES 36 (2005) 2146-2155

L Montabone, SR Lewis, PL Read

We study the interannual variability of dust storms on Mars in an assimilation of thermal profiles and dust opacity observations into a general circulation model for the Martian atmosphere. The observations have been provided by the thermal emission spectrometer aboard the Mars Global Surveyor spacecraft during the scientific mapping phase over more than two complete Martian years, which include three dusty seasons in southern spring. A comparison between dust seasons which are characterized only by regional storms and the global, planet-encircling dust storm of 2001 is performed, focusing on the meteorological conditions which can trigger the onset and development of the global storm, and its effects on the global circulation. (c) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.


Environmental predictions for the Beagle 2 lander, based on GCM climate simulations

Planetary and Space Science 52 (2004) 259-269

SJ Bingham, SR Lewis, CE Newman, PL Read

The Mars climate database (MCD) is a database of statistics based on output from physically consistent numerical model simulations which describe the climate and surface environment of Mars. It is used here to predict the meteorological environment of the Beagle 2 lander site. The database was constructed directly on the basis of output from multiannual integrations of two general circulation models, developed jointly at Laboratoire de Météorologie Dynamique du Centre National de la Recherche Scientifique, France, and the University of Oxford, UK. In an atmosphere with dust opacities similar to that observed by Mars Global Surveyor, the predicted surface temperature at the time of landing (Ls=322°, 13:00 local time), is ∼267 K, and varying between ∼186 and 268 K over the Martian day. The predicted air temperature at 1 m above the surface, the height of the fully extended Beagle 2 robot arm, is ∼258 K at the time of landing. The expected mean wind near the surface on landing is ∼5 ms-1 north-westerly in direction, becoming more southerly over the mission. An increase in mean surface pressure is expected during the mission. Heavy global dust storm predictions are discussed; conditions which may only occur in the extreme as the expected time of landing is around the end of the main dust storm period. Past observations show approximately a one in five chance of a large-scale dust storm in a whole Mars year over the landing region, Isidis Planitia. This statistic results from observations of global, encircling, regional and local dust storms but does not include any small-scale dust "events" such as dust devils. © 2003 Elsevier Ltd. All rights reserved.


The Martian climate revisited

Springer Verlag, 2004

PL Read, SR Lewis

latest techniques of atmospheric modelling, The Martian Climate Revisited provides a comprehensive summary of our knowledge and current understanding of the meteorology and climate of Mars from the viewpoint of atmospheric scientists .


Dynamics of Jupiter's atmosphere

in Jupiter, Cambridge Univ Pr (2004) 105-128

A Ingersoll, TE Dowling, PJ Gierasch, GS Orton, PL Read, A Sánchez-Lavega, AP Showman, AA Simon-Miller, AR Vasavada

Banded structure: belts and zones, changes in zonal velocity, evidence of upwelling and downwelling; Dicrete features: great red spot, white ovals and other anticyclones, cyclonic features, eddy momentum flux; Temperatures and vertical structure: global temperature variations, thermal waves, vertical structure - winds, temperature; Moist convection and lightning: lightning distribution, convective heat flux and structure of the lightning clouds, energy of lightning flashes, depth of lightning, models of moist convection; Models of the zonal jets: banding controlled in the weather layer, deep winds and stability of the jets, banding controlled in the interior, modes of internal heat transfer, banding controlled by tides, equatorial superrotation; Models of discrete features: stabel vortices, statistical mechanics models, equatorial hot spots and the Galileo probe; Unanswered questions and possible solutions.


A calibrated, non-invasive method for measuring the internal interface height field at high resolution in the rotating, two-layer annulus

GEOPHYSICAL AND ASTROPHYSICAL FLUID DYNAMICS 98 (2004) 453-471

PD Williams, PL Read, TWN Haine


Stochastic resonance in a nonlinear model of a rotating, stratified shear flow, with a simple stochastic inertia-gravity wave parameterization

NONLINEAR PROCESSES IN GEOPHYSICS 11 (2004) 127-135

PD Williams, TWN Haine, PL Read


Estimation of dynamical invariants without embedding by recurrence plots

CHAOS 14 (2004) 234-243

M Thiel, MC Romano, PL Read, J Kurths

Pages