Publications


A climate database for Mars

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS 104 (1999) 24177-24194

SR Lewis, M Collins, PL Read, F Forget, F Hourdin, R Fournier, C Hourdin, O Talagrand, JP Huot


The effect of sloping boundaries on baroclinic instability in two related internally heated, rotating fluid systems

PHYSICS AND CHEMISTRY OF THE EARTH PART B-HYDROLOGY OCEANS AND ATMOSPHERE 24 (1999) 481-486

ME Bastin, PL Read


Spatially inhomogeneous random advection

12TH CONFERENCE ON ATMOSPHERIC AND OCEANIC FLUID DYNAMICS (1999) 307-311

K Ngan, RT Pierrehumbert, AMS, AMS


Dynamics of a passive tracer in a velocity field of four identical point vortices

JOURNAL OF FLUID MECHANICS 394 (1999) 137-174

S Boatto, RT Pierrehumbert


Improved general circulation models of the Martian atmosphere from the surface to above 80 km

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS 104 (1999) 24155-24175

F Forget, F Hourdin, R Fournier, C Hourdin, O Talagrand, M Collins, SR Lewis, PL Read, JP Huot


Subtropical water vapor as a mediator of rapid global climate change

in Geophysical Monograph Series, 112 (1999) 339-361

RT Pierrehumbert

© 1999 by the American Geophysical Union. This article surveys the essential features of atmospheric water vapor dynamics needed to address current issues regarding the possible role of water vapor changes in mediating climate fluctuations on the millennial to Milankovic time scales. The focus is on the subtropics, which afford the most interesting possibilities for significant feedbacks. The observed distribution of water vapor, the amount by which water vapor must change in order to cause a significant temperature change, and the physical factors that determine the water vapor content of the subtropical atmosphere are discussed. It is shown that halving the subtropical relative humidity would lead to a 2.5K cooling of the tropics, while doubling it would lead to a 3K warming. The humidity content of the subtropics could be reduced by enhancing subsidence, reducing transient eddy activity, or contracting the convective region. Further work is needed to determine which, if any, of these changes occur in concert with the observed millennial and longer scale climate fluctions.


Experiments on a barotropic rotating shear layer. Part 1. Instability and steady vortices

JOURNAL OF FLUID MECHANICS 383 (1999) 143-173

WG Fruh, PL Read


Flow-field and point velocity measurements in a barotropically unstable shear layer

PHYSICS AND CHEMISTRY OF THE EARTH PART B-HYDROLOGY OCEANS AND ATMOSPHERE 24 (1999) 461-466

WG Fruh, PL Read


Experiments on the structure of baroclinic waves and zonal jets in an internally heated, rotating, cylinder of fluid

PHYSICS OF FLUIDS 10 (1998) 374-389

ME Bastin, PL Read


On the scattering greenhouse effect of CO2 ice clouds

JOURNAL OF THE ATMOSPHERIC SCIENCES 55 (1998) 1897-1903

RT Pierrehumbert, C Erlick


Evidence for control of Atlantic subtropical humidity by large scale advection

GEOPHYSICAL RESEARCH LETTERS 25 (1998) 4537-4540

RT Pierrehumbert, R Roca


Lateral mixing as a source of subtropical water vapor

GEOPHYSICAL RESEARCH LETTERS 25 (1998) 151-154

RT Pierrehumbert


Wave interactions and baroclinic chaos: A paradigm for long timescale variability in planetary atmospheres

CHAOS SOLITON FRACT 9 (1998) 231-249

PL Read, M Collins, WG Fruh, SR Lewis, AF Lovegrove

Baroclinic instability is the principal mode of non-axisymmetric flow in the large-scale atmospheric circulation at mid-latitudes, and is responsible for oganising the structure and behaviour of major weather systems. This instability can also be fruitfully studied in the laboratory under controlled conditions. In this paper, we review recent work carried out by the authors and collaborators on various routes to chaotic behaviour in rotating, stratified flows. Results include the discovery of new multi-mode regimes in which small ensembles of baroclinic waves interact in a nonlinear mode competition with the thermally-driven axisymmetric component of the Bow, generating chaotic oscillatory variability on very long timescales. We discuss various attempts to capture this type of behaviour in simple models, and consider the significance of the phenomenon as a paradigm for understanding the nature of long timescale variability in the climates of the Earth and Mars. (C) 1998 Elsevier Science Ltd. All rights reserved.


A comparison of empirical orthogonal decomposition methods in baroclinic flows

Dynamics of Atmospheres and Oceans 27 (1998) 649-660

AV Stephen, IM Moroz, PL Read, WG Früh

The relative merits of three contrasting empirical orthogonal decomposition methods in common use (namely, Proper Orthogonal Decomposition, Biorthogonal Decomposition and Multivariate Singular Systems Analysis) are considered as applied to baroclinic flow data. The regimes analysed are a steady, drifting wave, a modulated amplitude vacillating wave flow and a neighbouring multi-mode state which exhibits intermittency. The results are used to make a qualitative comparison of the methods in terms of convergence properties, variance capture and eigenfunction structure. The feasibility of using the resulting empirical orthogonal functions to transform partial differential equations to ordinary differential equations by Galerkin projection is mentioned. © 1997 Elsevier Science B.V.


Investigation of Saturn's atmosphere by Cassini

PLANET SPACE SCI 46 (1998) 1315-1324

FW Taylor, SB Calcutt, PGJ Irwin, CA Nixon, PL Read, PJC Smith, TJ Vellacott

This paper considers the rationale for the exploration of Saturn's atmosphere by the Cassini mission, taking account of the key scientific questions posed by the earlier investigation by Voyager, and the capabilities of the instrumentation making up the Cassini payload. While by no means all objectives can be addressed by this particular configuration, in particular without a Saturn entry probe, if everything goes according to plan important progress should be possible on a number of key objectives. (C) 1998 Elsevier Science Ltd. All rights reserved.


Mode selection, wave breaking and parametric sensitivity in the quasi-biennial oscillation

QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY 123 (1997) 2041-2068

X Li, PL Read, DG Andrews


Laboratory and numerical studies of baroclinic waves in an internally heated rotating fluid annulus: A case of wave/vortex duality?

JOURNAL OF FLUID MECHANICS 337 (1997) 155-191

PL Read, SR Lewis, R Hide


A GCM climate database for Mars: For mission planning and for scientific studies

ADV SPACE RES 19 (1997) 1213-1222

PL Read, M Collins, F Forget, R Fournier, F Hourdin, SR Lewis, O Talagrand, FW Taylor, NPJ Thomas

The construction of a new database of statistics on the climate and environment of the Martian atmosphere is currently under way, with the support of the European Space Agency. The primary objectives of this database are to provide information for mission design specialists on the mean state and variability of the Martian environment in unprecedented detail, through the execution of a set of carefully validated simulations of the Martian atmospheric circulation using comprehensive numerical general circulation models. The formulation of the models used are outlined herein, noting especially new improvements in various schemes to parametrize important physical processes, and the scope of the database to be constructed is described. A novel approach towards the representation of large-scale variability in the output of the database using empirical eigenfunctions derived from statistical analyses of the numerical simulations, is also discussed. It is hoped that the resulting database will be of value for both scientific and engineering studies of Mars' atmosphere and near-surface environment. (C) 1997 COSPAR. Published by Elsevier Science Ltd.


A laboratory study of baroclinic waves and turbulence in an internally heated rotating fluid annulus with sloping endwalls

JOURNAL OF FLUID MECHANICS 339 (1997) 173-198

ME Bastin, PL Read


Gravity wave drag in a global circulation model of the Martian atmosphere: Parameterisation and validation

ADV SPACE RES 19 (1997) 1245-1254

M Collins, SR Lewis, PL Read

The effect of orographically generated breaking gravity waves is parametrised in a global circulation model of the Martian atmosphere using schemes adapted from terrestrial models. The schemes are 'tuned' by comparing model integrations with and without gravity wave drag with temperatures derived from the Mariner 9 IRIS instrument. Without gravity wave drag the global circulation model temperature field has excessively cold upper level polar regions. Gravity wave drag can correct for such cold temperatures by warming the atmosphere adiabatically via a dynamically induced circulation. The model climatology is significantly improved in the polar regions with the introduction of the parametrisation. (C) 1997 COSPAR. Published by Elsevier Science Ltd.

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