Publications


The advection-diffusion problem for stratospheric flow. Part II: Probability distribution function of tracer gradients

JOURNAL OF THE ATMOSPHERIC SCIENCES 59 (2002) 2830-2845

YY Hu, RT Pierrehumbert


The hydrologic cycle in deep-time climate problems.

Nature 419 (2002) 191-198

RT Pierrehumbert

Hydrology refers to the whole panoply of effects the water molecule has on climate and on the land surface during its journey there and back again between ocean and atmosphere. On its way, it is cycled through vapour, cloud water, snow, sea ice and glacier ice, as well as acting as a catalyst for silicate-carbonate weathering reactions governing atmospheric carbon dioxide. Because carbon dioxide affects the hydrologic cycle through temperature, climate is a pas des deux between carbon dioxide and water, with important guest appearances by surface ice cover.


Bifurcations and instabilities in rotating, two-layer fluids: II. beta-plane

NONLINEAR PROC GEOPH 9 (2002) 289-309

AF Lovegrove, IM Moroz, PL Read

In this paper, we show that the behavior of weakly nonlinear waves in a 2-layer model of baroclinic instability on a P-plane with varying viscosity is determined by a single degenerate codimension three bifurcation. In the process, we show how previous studies, using the method of multiple scales to derive evolution equations for the slowly varying amplitude of the growing wave, arise as special limits of the general evolution description.


Testing paleogeographic controls on a Neoproterozoic snowball Earth

GEOPHYSICAL RESEARCH LETTERS 29 (2002) ARTN 1515

CJ Poulsen, RL Jacob, RT Pierrehumbert, TT Huynh


Surface quasigeostrophic turbulence: The study of an active scalar.

Chaos (Woodbury, N.Y.) 12 (2002) 439-450

J Sukhatme, RT Pierrehumbert

We study the statistical and geometrical properties of the potential temperature (PT) field in the surface quasigeostrophic (SQG) system of equations. In addition to extracting information in a global sense via tools such as the power spectrum, the g-beta spectrum, and the structure functions we explore the local nature of the PT field by means of the wavelet transform method. The primary indication is that an initially smooth PT field becomes rough (within specified scales), though in a qualitatively sparse fashion. Similarly, initially one-dimensional iso-PT contours (i.e., PT level sets) are seen to acquire a fractal nature. Moreover, the dimensions of the iso-PT contours satisfy existing analytical bounds. The expectation that the roughness will manifest itself in the singular nature of the gradient fields is confirmed via the multifractal nature of the dissipation field. Following earlier work on the subject, the singular and oscillatory nature of the gradient field is investigated by examining the scaling of a probability measure and a sign singular measure, respectively. A physically motivated derivation of the relations between the variety of scaling exponents is presented, the aim being to bring out some of the underlying assumptions which seem to have gone unnoticed in previous presentations. Apart from concentrating on specific properties of the SQG system, a broader theme of the paper is a comparison of the diagnostic inertial range properties of the SQG system with both the two- and three-dimensional Euler equations. (c) 2002 American Institute of Physics.


Abrupt Climate Change: Inevitable Surprises

National Academies Press, 2002

COAC Change, NR Council, BOASA Climate, DOEAL Studies, PR Board, OS Board

Based on the best and most current research available, this book surveys the history of climate change and makes a series of specific recommendations for the future.


Editorial

Nonlinear Processes in Geophysics 8 (2001) 191-192

PL Read


Transition to geostrophic turbulence in the laboratory, and as a paradigm in atmospheres and oceans

SURVEYS IN GEOPHYSICS 22 (2001) 265-317

PL Read


Physical Climate Processes and Feedbacks

in Climate Change 2001: The Scientific Basis Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press (2001) 7

T Stocker, RT Pierrehumbert, G Clarke, TN Palmer, K Trenberth, R Lindzen

Climate Change 2001: The Scientific Basis is the most comprehensive and up-to-date scientific assessment of past, present and future climate change.


The advection-diffusion problem for stratospheric flow. Part I: Concentration probability distribution function

JOURNAL OF THE ATMOSPHERIC SCIENCES 58 (2001) 1493-1510

Y Hu, RT Pierrehumbert


A new approach to stable isotope-based paleoaltimetry: implications for paleoaltimetry and paleohypsometry of the High Himalaya since the Late Miocene

EARTH AND PLANETARY SCIENCE LETTERS 188 (2001) 253-268

DB Rowley, RT Pierrehumbert, BS Currie


Impact of ocean dynamics on the simulation of the Neoproterozoic "snowball Earth"

GEOPHYSICAL RESEARCH LETTERS 28 (2001) 1575-1578

CJ Poulsen, RT Pierrehumbert, RL Jacob


Bifurcations and instabilities in rotating two-layer fluids: I. f-plane

Nonlinear Processes in Geophysics 8 (2001) 21-36

AF Lovegrove, IM Moroz, PL Read

In this paper, we show that the behaviour of weakly nonlinear waves in a 2-layer model of baroclinic instability on an f-plane with varying viscosity is determined by a single, degenerate codimension three bifurcation. In the process, we show how previous studies, using the method of multiple scales to derive evolution equations for the slowly varying amplitude of the growing wave, arise as special limits of the general evolution description. A companion study will extend the results to a β-plane.


Achievements and directions in nonlinear geophysics - Editorial

NONLINEAR PROCESSES IN GEOPHYSICS 8 (2001) 191-192

PL Read


Atmospheric pCO(2) sensitivity to the biological pump in the ocean

GLOBAL BIOGEOCHEMICAL CYCLES 14 (2000) 1219-1230

DE Archer, G Eshel, A Winguth, W Broecker, R Pierrehumbert, M Tobis, R Jacob


Generation of inertia-gravity waves in a baroclinically unstable fluid

QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY 126 (2000) 3233-3254

AF Lovegrove, PL Read, CJ Richards


An evaluation of Eulerian and semi-Lagrangian advection schemes in simulations of rotating, stratified flows in the laboratory. Part I: Axisymmetric flow

MONTHLY WEATHER REVIEW 128 (2000) 2835-2852

PL Read, NPJ Thomas, SH Risch


A mechanistic model of the quasi-quadrennial oscillation in Jupiter's stratosphere

PLANET SPACE SCI 48 (2000) 637-669

X Li, PL Read

An analytical model, previously developed for investigating the propagation of equatorially-trapped waves on an equatorial beta-plane in a uniform zonal flow in the presence of Rayleigh friction and Newtonian cooling in the Earth's stratosphere, is applied to Jupiter's upper troposphere and lower stratosphere. By analogy with the Earth, a 'spectral window' is identified for each of the main classes of equatorial wave mode, suggesting a mode-selection criterion for the dominant modes observed in association with strong wave-zonal flow interactions in the stratosphere. The modes favoured by this approach are compared with recent observations of wave activity and the quasi-quadrennial oscillation (QQO) in Jupiter's tropical atmosphere. Two modes with zonal wavenumber k similar to 8-11 are identified which may correspond to: (i) an equatorial Rossby mode moving eastward at around 100 m s(-1): and (ii) a mixed Rossby-gravity mode which is similar to stationary in System III, apparently excited by a wave source moving with the zonal wind in the deep troposphere. A Kelvin mode is also predicted to be present, but observational evidence for this mode is lacking to date. A numerical model, capable of solving for wave structures and wave-zonal flow interactions in arbitrary zonal flows using a Hermite spectral method, is adapted to conditions in Jupiter's stratosphere. The latter numerical model is shown to successfully simulate a plausible QQO with a period around four Earth years, given a single pair of forced Kelvin and MRG modes with tropospheric amplitudes consistent with observations. This model demonstrates that the QQO may indeed result, at least in principle, from interactions of a small number of equatorially-trapped wave modes with the zonal flow in the stratosphere. The selection of wave modes taking part in this process is not unique, however, and the precise identification of the relevant modes from observations remains elusive. (C) 2000 Elsevier Science Ltd. All rights reserved.


Spatially correlated and inhomogeneous random advection

PHYSICS OF FLUIDS 12 (2000) 822-834

K Ngan, RT Pierrehumbert


'Equability' in an unequal world: The early Eocene revisited

GFF 122 (2000) 101-102

PJ Markwick, PJ Valdes, BW Sellwood, RT Pierrehumbert

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