Publications


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


Wave interactions and the transition to chaos of baroclinic waves in a thermally driven rotating annulus

PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES 355 (1997) 101-153

WG Fruh, PL Read


Data assimilation with a Martian atmospheric GCM: An example using thermal data

ADV SPACE RES 19 (1997) 1267-1270

SR Lewis, M Collins, PL Read

Data assimilation is a technique for the analysis of atmospheric observations which combines current information with prior knowledge from previous observations, summarized and forecast in time via the use of a numerical model. A sequential data assimilation scheme has been implemented with a full general circulation model (GCM) of the martian atmosphere for the first time, and has been adapted for the types of atmospheric data which might be expected in the near future, e.g. remote-sensed temperature profiles from a polar orbiter mission such as Mars Surveyor '96 and '98. Tests demonstrate the performance of the scheme using artificial data generated from independent model experiments. (C) 1997 COSPAR. Published by Elsevier Science Ltd.


Lower-tropospheric heat transport in the Pacific storm track

JOURNAL OF THE ATMOSPHERIC SCIENCES 54 (1997) 1533-1543

KL Swanson, RT Pierrehumbert


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.


Baroclinic wave transitions in the Martian atmosphere

ICARUS 120 (1996) 344-357

M Collins, SR Lewis, PL Read, F Hourdin


Martian atmospheric data assimilation with a simplified general circulation model: Orbiter and lander networks

Planetary and Space Science 44 (1996) 1395-1409

SR Lewis, PL Read, M Collins

A meteorological data assimilation scheme for the martian atmosphere has been implemented and tested, based on techniques used in the current operational scheme for weather forecasting at the U.K. Meteorological Office. The scheme has been interfaced with a range of simple models and with the martian GCM currently under simultaneous development at Laboratoire de Météorologie Dynamique du CNRS in Paris and at Oxford. As well as the interpretation of data from any future spacecraft, the assimilation scheme may be used for comparisons between different models, for model validation using earlier martian data, and for data impact studies to assist in planning new missions. Despite proposed new missions to Mars, observations of the atmosphere of Mars in the near future are still likely to be very sparse compared to those of the Earth (perhaps comprising a single orbiter and a few surface stations at any one time) and the scheme has been adapted with this in mind. Twin model experiments are conducted in which simulated observations are generated from a second model started from different initial conditions. Such experiments reveal the importance of surface pressure measurements (in combination with an accurate topographic map, such as will be available from laser altimetry) in the determination of the amplitude of large-scale atmospheric waves. It is shown that atmospheric temperature profiles from a remote-sensing instrument on a polar orbiting satellite combined with simultaneous surface pressure observations at a limited number of sites, as planned for the InterMarsNet mission, is a useful scenario for data assimilation. Copyright © 1996 Elsevier Science Ltd.


Anomalous scaling of high cloud variability in the tropical Pacific

GEOPHYSICAL RESEARCH LETTERS 23 (1996) 1095-1098

RT Pierrehumbert


Martian atmospheric data assimilation with a simplified general circulation model: Orbiter and lander networks

PLANET SPACE SCI 44 (1996) 1395-1409

SR Lewis, PL Read, M Collins

A meteorological data assimilation scheme for the martian atmosphere has been implemented and tested, based on techniques used in the current operational scheme for weather forecasting at the U.K. Meteorological Office. The scheme has been interfaced with a range of simple models and with the martian GCM currently under simultaneous development at Laboratoire de Meteorologie Dynamique du CNRS in Paris and at Oxford. As well as the interpretation of data from any future spacecraft, the assimilation scheme may be used for comparisons between different models, for model validation using earlier martian data, and for data impact studies to assist in planning new missions. Despite proposed new missions to Mars, observations of the atmosphere of Mars in the near future are still likely to be very sparse compared to those of the Earth (perhaps comprising a single orbiter and a few surface stations at any one time) and the scheme has been adapted with this in mind. Twin model experiments are conducted in which simulated observations are generated from a second model started from different initial conditions. Such experiments reveal the importance of surface pressure measurements (in combination with an accurate topographic map, such as will be available from laser altimetry) in the determination of the amplitude of large-scale atmospheric waves. It is shown that atmospheric temperature profiles from a remote-sensing instrument on a polar orbiting satellite combined with simultaneous surface pressure observations at a limited number of sites, as planned for the InterMarsNet mission, is a useful scenario for data assimilation. Copyright (C) 1996 Elsevier Science Ltd


Numerical modelling of the general circulation of the Martian atmosphere

European Space Agency, (Special Publication) ESA SP (1996) 315-320

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

General Circulation Models, originally developed for the needs of terrestrial meteorology and climatology, have become in the last twenty years a central tool of Martian climate studies. This paper descrcibes how numerical simulation can be also used for determining the environment for a probe. It also highlights the recent modellig efforts which have been made jointly at LMD/CNRS (Paris) and AOPP (Oxford) to develop a new-generation General Circulation Model in order to produce a Martian climate database for the European Space Agency.


A climate database for the Martian atmosphere

European Space Agency, (Special Publication) ESA SP (1996) 323-327

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

A new engineering model of the environment of Mars is outlined. The model is based on a database of statistics computed from a state-of-the-art Global Circulation Model of the martian atmosphere which represents our best knowledge of the atmosphere to date. A novel scheme for the representation of large scale variability in the engineering model, in terms of an optimal set of basis functions derived from the Global Circulation Model, is also outlined and shown to be an efficient and accurate method of representing correlated structures in vertical profiles.


Baroclinic instability

(1995)

RT Pierrehumbert, KL Swanson

The study of baroclinic instability has its origins in attempts to explain the genesis of midlatitude synoptic storm systems. The authors provide an account of the fundamental material and unfamiliar aspects of the linear theory. Essential observational background is provided in section 2, and the mathematical basics are laid out in section 3. The review for the most part focuses on quasigeostrophic dynamics, considering only dry dynamics. Discussion is slanted towards the terrestrial atmosphere. Stability criteria are treated in section 4, and normal modes are discussed in section 5. Aspects of the linear initial value problem are taken up in section 6. Section 7 considers briefly the difficult subject of nonlinear equilibration. Finally, section 8, takes stock of where the subject stands and where it is going. (from Authors)


Baroclinic instability

(1995)

RT Pierrehumbert, KL Swanson

The study of baroclinic instability has its origins in attempts to explain the genesis of midlatitude synoptic storm systems. The authors provide an account of the fundamental material and unfamiliar aspects of the linear theory. Essential observational background is provided in section 2, and the mathematical basics are laid out in section 3. The review for the most part focuses on quasigeostrophic dynamics, considering only dry dynamics. Discussion is slanted towards the terrestrial atmosphere. Stability criteria are treated in section 4, and normal modes are discussed in section 5. Aspects of the linear initial value problem are taken up in section 6. Section 7 considers briefly the difficult subject of nonlinear equilibration. Finally, section 8, takes stock of where the subject stands and where it is going. (from Authors)


SURFACE QUASI-GEOSTROPHIC DYNAMICS

JOURNAL OF FLUID MECHANICS 282 (1995) 1-20

IM HELD, RT PIERREHUMBERT, ST GARNER, KL SWANSON


THERMOSTATS, RADIATOR FINS, AND THE LOCAL RUNAWAY GREENHOUSE

JOURNAL OF THE ATMOSPHERIC SCIENCES 52 (1995) 1784-1806

RT PIERREHUMBERT


POTENTIAL VORTICITY HOMOGENIZATION AND STATIONARY WAVES

JOURNAL OF THE ATMOSPHERIC SCIENCES 52 (1995) 990-994

KL SWANSON, RT PIERREHUMBERT


The mixing paradigm: Towards a Lagrangian view of the general circulation

ENVIRONMENT AND QUALITY OF LIFE (1995) 102-113

RT PIERREHUMBERT


WESTERN BOUNDARY CURRENTS IN THE MARTIAN ATMOSPHERE - NUMERICAL SIMULATIONS AND OBSERVATIONAL EVIDENCE

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS 100 (1995) 5485-5500

MM JOSHI, SR LEWIS, PL READ, DC CATLING

Pages