Publications


Climate of the Neoproterozoic

ANNUAL REVIEW OF EARTH AND PLANETARY SCIENCES, VOL 39 39 (2011) 417-460

RT Pierrehumbert, DS Abbot, A Voigt, D Koll


A PALETTE OF CLIMATES FOR GLIESE 581g

ASTROPHYSICAL JOURNAL LETTERS 726 (2011) ARTN L8

RT Pierrehumbert


Initiation of a Marinoan Snowball Earth in a state-of-the-art atmosphere-ocean general circulation model

CLIMATE OF THE PAST 7 (2011) 249-263

A Voigt, DS Abbot, RT Pierrehumbert, J Marotzke


Sea glacier flow and dust transport on Snowball Earth

GEOPHYSICAL RESEARCH LETTERS 38 (2011) ARTN L17501

D Li, 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.


PyCCSM: Prototyping a python-based community climate system model

ANZIAM Journal 48 (2010) C1112-C1130

M Tobis, M Steder, J Walter Larson, RT Pierrehumbert, RL Jacob, ET Ong

© Austral. Mathematical Soc. 2010. Coupled climate models are multiphysics models comprising multi-ple separately developed codes that are combined into a single physical system. This composition of codes is amenable to a scripting solution, and Python is a language that offers many desirable properties for this task. We have prototyped a Python coupling and control infrastruc-ture for version 3.0 of the Community Climate System Model (ccsm3). Our objective was to improve dramatically ccsm3's already exible coupling facilities to enable research uses of the model not currently supported. We report the progress in the first steps in this effort: the construction of Python bindings for the Model Coupling Toolkit, a key piece of third-party coupling middleware used in ccsm3, and a Python-based ccsm3 coupler (pypcl) application. We report prelim-inary performance results for this new system, which we call pyccsm. We find pyccsm is significantly slower than its Fortran counterpart, and explain how pypcl's performance may be improved to support production runs. We believe our results augur well for the use of Python in the top-level coupling and organisation of large parallel multiphysics and multiscale applications.


Mudball: Surface dust and Snowball Earth deglaciation

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 115 (2010) ARTN D03104

DS Abbot, RT Pierrehumbert


The Importance of Ice Vertical Resolution for Snowball Climate and Deglaciation

JOURNAL OF CLIMATE 23 (2010) 6100-6109

DS Abbot, I Eisenman, RT Pierrehumbert


Element cycling and the evolution of the Earth System

GEOCHIMICA ET COSMOCHIMICA ACTA 74 (2010) A339-A339

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


The role of ocean dynamics in the optimal growth of tropical SST anomalies

Journal of Physical Oceanography 40 (2010) 983-1003

L Zanna, P Heimbach, AM Moore, E Tziperman

The role of ocean dynamics in optimally exciting interannual variability of tropical sea surface temperature (SST) anomalies is investigated using an idealized-geometry ocean general circulation model. Initial temperature and salinity perturbations leading to an optimal growth of tropical SST anomalies, typically arising from the nonnormal dynamics, are evaluated. The structure of the optimal perturbations is characterized by relatively strong deep salinity anomalies near the western boundary generating a transient amplification of equatorial SST anomalies in less than four years. The associated growth mechanism is linked to the excitation of coastal and equatorial Kelvin waves near the western boundary following a rapid geostrophic adjustment owing to the optimal initial temperature and salinity perturbations. The results suggest that the nonnormality of the ocean dynamics may efficiently create large tropical SST variability on interannual time scales in the Atlantic without the participation of air-sea processes or the meridional overturning circulation. An optimal deep initial salinity perturbation of 0.1 ppt located near the western boundary can result in a tropical SST anomaly of approximately 0.458C after nearly four years, assuming the dynamics are linear. Possible mechanisms for exciting such deep perturbations are discussed. While this study is motivated by tropical Atlantic SST variability, its relevance to other basins is not excluded. The optimal initial conditions leading to the tropical SST anomalies' growth are obtained by solving a generalized eigenvalue problem. The evaluation of the optimals is achieved by using the Massachusetts Institute of Technology general circulation model (MITgcm) tangent linear and adjoint models as well the the Arnoldi Package (ARPACK) software for solving large-scale eigenvalue problems. © 2010 American Meteorological Society.


Sensitivity of stable water isotopic values to convective parameterization schemes

GEOPHYSICAL RESEARCH LETTERS 36 (2009) ARTN L23801

J-E Lee, R Pierrehumbert, A Swann, BR Lintner


Global warming, convective threshold and false thermostats

GEOPHYSICAL RESEARCH LETTERS 36 (2009) ARTN L21805

IN Williams, RT Pierrehumbert, M Huber


The impact of methane thermodynamics on seasonal convection and circulation in a model Titan atmosphere

ICARUS 203 (2009) 250-264

JL Mitchell, RT Pierrehumbert, DMW Frierson, R Caballero


The snowball Earth aftermath: Exploring the limits of continental weathering processes

EARTH AND PLANETARY SCIENCE LETTERS 277 (2009) 453-463

G Le Hir, Y Donnadieu, Y Godderis, RT Pierrehumbert, GR Halverson, M Macouin, A Nedelec, G Ramstein


Radiative transfer in CO2-rich paleoatmospheres

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 114 (2009) ARTN D18112

I Halevy, RT Pierrehumbert, DP Schrag


Causal or casual link between the rise of nannoplankton calcification and a tectonically-driven massive decrease in Late Triassic atmospheric CO2?

EARTH AND PLANETARY SCIENCE LETTERS 267 (2008) 247-255

Y Godderis, Y Donnadieu, C de Vargas, RT Pierrehumbert, G Dromart, B van de Schootbrugge


Axisymmetric, nearly inviscid circulations in non-condensing radiative-convective atmospheres

QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY 134 (2008) 1269-1285

R Caballero, RT Pierrehumbert, JL Mitchell


Data discrepancies in solar-climate link.

Science (New York, N.Y.) 320 (2008) 746-

RT Pierrehumbert


Optimal surface excitation of the thermohaline circulation

Journal of Physical Oceanography 38 (2008) 1820-1830

L Zanna, E Tziperman

The amplification of thermohaline circulation (THC) anomalies resulting from heat and freshwater forcing at the ocean surface is investigated in a zonally averaged coupled ocean-atmosphere model. Optimal initial conditions of surface temperature and salinity leading to the largest THC growth are computed, and so are the structures of stochastic surface temperature and salinity forcing that excite maximum THC variance (stochastic optimals). When the THC amplitude is defined as its sum of squares (equivalent to using the standard L2 norm), the nonnormal linearized dynamics lead to an amplification with a time scale on the order of 100 yr. The optimal initial conditions have a vanishing THC anomaly, and the complex amplification mechanism involves the advection of both temperature and salinity anomalies by the mean flow and of the mean temperature and salinity by the anomaly flow. The L2 characterization of THC anomalies leads to physically interesting results, yet to a mathematically singular problem. A novel alternative characterizing the THC amplitude by its maximum value, as often done in general circulation model studies, is therefore introduced. This complementary method is shown to be equivalent to using the L-infinity norm, and the needed mathematical approach is developed and applied to the THC problem. Under this norm, an amplification occurs within 10 yr explained by the classic salinity advective feedback mechanism. The analysis of the stochastic optimals shows that the character of the THC variability may be very sensitive to the spatial pattern of the surface forcing. In particular, a maximum THC variance and long-time-scale variability are excited by a basin-scale surface forcing pattern, while a significantly higher frequency and to some extent a weaker variability are induced by a smooth and large-scale, yet mostly concentrated in polar areas, surface forcing pattern. Overall, the results suggest that a large THC variability can be efficiently excited by atmospheric surface forcing, and the simple model used here makes several predictions that would be interesting to test using more complex models. © 2008 American Meteorological Society.


Nonnormal thermohaline circulation dynamics in a coupled ocean-atmosphere GCM

Journal of Physical Oceanography 38 (2008) 588-604

E Tziperman, L Zanna, C Penland

Using the GFDL coupled atmosphere-ocean general circulation model CM2.1, the transient amplification of thermohaline circulation (THC) anomalies due to its nonnormal dynamics is studied. A reduced space based on empirical orthogonal functions (EOFs) of temperature and salinity anomaly fields in the North Atlantic is constructed. Under the assumption that the dynamics of this reduced space is linear, the propagator of the system is then evaluated and the transient growth of THC anomalies analyzed. Although the linear dynamics are stable, such that any initial perturbation eventually decays, nonnormal effects are found to result in a significant transient growth of temperature, salinity, and THC anomalies. The growth time scale for these anomalies is between 5 and 10 yr, providing an estimate of the predictability time of the North Atlantic THC in this model. There are indications that these results are merely a lower bound on the nonnormality of THC dynamics in the present coupled GCM. This seems to suggest that such nonnormal effects should be seriously considered if the predictability of the THC is to be quantitatively evaluated from models or observations. The methodology presented here may be used to produce initial perturbations to the ocean state that may result in a stricter estimate of ocean and THC predictability than the common procedure of initializing with an identical ocean state and a perturbed atmosphere. © 2008 American Meteorological Society.

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