Laurent Fairhead

• French National Centre for Scientific Research

We demonstrate a new approach for climate model tuning in a realistic situation. Our approach, the mathematical foundations and technical details of which are given in Part I, systematically uses a single‐column configuration of a global atmospheric model on test cases for which reference large‐eddy‐simulations are available. The space of free para...

Plain Language Summary Evaluating current and future risks for natural and human systems associated with climate change is largely based on numerical simulations performed with models of the climate system, which includes the atmosphere, the land, the ocean, the cryosphere, and the oceanic and terrestrial biosphere. Various steps are involved in th...

The cloud parameterizations of the LMDZ6A climate model (the atmospheric component of the IPSL‐CM6 Earth system model) are entirely described and the global cloud distribution and cloud radiative effects are evaluated against the CALIPSO‐CloudSat and CERES observations. The cloud parameterizations in recent versions of LMDZ favor an object‐oriented...

Abstract This study presents the version of the LMDZ global atmospheric model used as the atmospheric component of the Institut Pierre Simon Laplace coupled model (IPSL‐CM6A‐LR) to contribute to the 6th phase of the international Coupled Model Intercomparison Project (CMIP6). This LMDZ6A version includes original convective parameterizations that d...

Abstract This study presents the global climate model IPSL‐CM6A‐LR developed at Institut Pierre‐Simon Laplace (IPSL) to study natural climate variability and climate response to natural and anthropogenic forcings as part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). This article describes the different model components, t...

The Antarctic continent is a vast desert, the coldest and the most unknown area containing the main fresh water reservoir. Current global warming could threaten this ice cap, leading to a sea level rise. A main goal of the APRES3 (Antarctic Precipitation, Remote Sensing from Surface and Space) project is to document and understand current precipita...

We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, a...

Based on a decade of research on cloud processes, a new version of the LMDZ atmospheric general circulation model has been developed that corresponds to a complete recasting of the parameterization of turbulence, convection and clouds. This LMDZ5B version includes a mass-flux representation of the thermal plumes or rolls of the convective boundary...

This paper presents the major characteristics of the Institut Pierre Simon Laplace (IPSL) coupled ocean-atmosphere general circulation model. The model components and the coupling methodology are described, as well as the main characteristics of the climatology and interannual variability. The model results of the standard version used for IPCC cli...

The LMDZ4 general circulation model is the atmospheric component of the IPSL–CM4 coupled model which has been used to perform climate change simulations for the 4th IPCC assessment report. The main aspects of the model climatology (forced by observed sea surface temperature) are documented here, as well as the major improvements with respect to the...

Résumé: Dans le cadre de la préparation du 4e rapport du Groupe Intergouvernemental sur l'Evolution du Climat (GIEC) qui doit paraître début 2007, les principales équipes de modélisation du climat de part le monde ont réalisé un important exercice coordonné de simulation de l'évolution du climat au cours du 20e et du 21e siècle. Nous présentons ici...

Dans le cadre de la préparation du 4e rapport du Groupe intergouvernemental sur l'évolution du climat (Giec), qui doit paraître début 2007, les principales équipes de modélisation de par le monde ont réalisé un important exercice coordonné de simulation de l'évolution du climat au cours des XXe et XXIe siècles. Nous présentons ici les résultats obt...

A climatology of the stratosphere is determined from a 20-year integration with the stratospheric version of the Atmospheric General Circulation Model LMDz. The model has an upper boundary at near 65km, uses a Doppler spread non-orographic gravity waves drag parameterization and a subgrid-scale orography parameterization. It also has a Rayleigh dam...

1] In this study, we examine the time evolution of the relative contribution of sulfate aerosols and greenhouse gases to anthropogenic climate change. We use the new IPSL-CM4 coupled climate model for which the first indirect effect of sulfate aerosols has been calibrated using POLDER satellite data. For the recent historical period the sulfate aer...

In the course of the development of the IPSL coupled model, a significant work has been devoted during the last three years to the improvement of the atmospheric physics. Switching from Tiedtke (Mon. Wea. Rev., 117:1179-1800, 1989) to Emanuel (J. of Atmopsh. Sci., 48:2313-2335, 1991) convection scheme resulted in a better distribution of convective...

We study the response of the land biosphere to climate change by coupling a climate general circulation model to a global carbon cycle model. This coupled model was forced by observed CO2 emissions for the 1860-1990 period and by the IPCC SRES-A2 emission scenario for the 1991-2100 period. During the historical period, our simulated Net Primary Pro...

We use an ocean-atmosphere general circulation model coupled to land and ocean carbon models to simulate the evolution of climate and atmospheric CO2 from 1860 to 2100. Our model reproduces the observed global mean temperature changes and the growth rate of atmospheric CO2 for the period 1860-2000. For the future, we simulate that the climate chang...

We describe the behaviour of 23 dynamical ocean-atmosphere models, in the context of comparison with observations in a common framework. Fields of tropical sea surface temperature (SST), surface wind stress and upper ocean vertically averaged temperature (VAT) are assessed with regard to annual mean, seasonal cycle, and interannual variability char...

An ensemble of twenty four coupled ocean-atmosphere models has been compared with respect to their performance in the tropical Pacific. The coupled models span a large portion of the parameter space and differ in many respects. The intercomparison includes TOGA (Tropical Ocean Global Atmosphere)-type models consisting of high-resolution tropical oc...

Future climate change due to increased atmospheric CO2 may affect land and ocean efficiency to absorb atmospheric CO2. Here, using climate and carbon three-dimensional models forced by a 1% per year increase in atmospheric CO2, we show that there is a positive feedback between the climate system and the carbon cycle. Climate change reduces land and...

 We examine the seasonal cycle of near-surface air temperature simulated by 17 coupled ocean-atmosphere general circulation models participating in the Coupled Model Intercomparison Project (CMIP). Nine of the models use ad hoc “flux adjustment” at the ocean surface to bring model simulations close to observations of the present-day climate. We gro...

The sensitivity of the interannual variations of the summer monsoons to imposed cloudiness has been studied with a general circulation model using the initial conditions prepared from the European Centre for Medium-Range Forecasts analyses of 1 May 1987 and 1988. The cloud optical properties in this global model are calculated from prognostically c...

Two transient CO2 experiments using two coupled general circulation models developed by the French GASTON group have been realized using the same methodology. No flux corrections at the air-sea interface were used in these experiments. The main features of the present climate are reasonably well captured by both coupled models in the control simula...

Two transient CO2 experiments using two coupled general circulation models developed by the French GASTON group have been realized using the same methodology. No flux corrections at the air-sea interface were used in these experiments. The main features of the present climate are reasonably well captured by both coupled models in the control simula...

Flux density measurements of four recycled pulsars, PSR 1620-26, PSR 1821-24, PSR 1855+09, and PSR 1937+21, have been made to determine their spectral indices in the range between 425 MHz to 3 GHz. The four objects are shown to have indices that range from –1.3 to –2.6. The luminosities of these four pulsars are spread over nearly three orders of m...

A study of the flux density and component emission of four millisecond radio pulsars shows that on average millisecond radio pulsars have steeper spectra than slow period pulsars. The results of flux density measurements of four millisecond pulsars, PSR 1620-26, 1821-24, 1855+09, and 1937+21, have been made to determine their spectral indices in th...

Flux density measurements of four millisecond pulsars, PSR 1620-26, 1821-24, PSR 1855 + 09, and PSR 1937 + 21, have been made to determine their spectral indices in the frequency range between 425 MHz and 3 GHz. The four objects are shown to have indices that range from -1.3 to -2.6. The luminosities of these four pulsars are spread over nearly thr...

A new analysis of the first two years of timing data acquired on the fast pulsar PSR 1937+214 at Arecibo is presented. Parameters are evaluated with various models based on two ephemerides, two atomic time scales and two TT-TB time transformations and comparison is carried out with previously published results. We provide evidence that systematic e...

An analytical formula for the time transformation TB-TT valid over a few thousand years around J2000 has been computed with an accuracy at the 1 ns level. The 127 coefficients presented in this paper provide a formula accurate at the 100 ns level. The numerical and analytical procedures to compute this transformation are discussed and compared. It...

A new analysis of the timing data acquired on the fast pulsar PSR1937+214 is presented. Parameters are evaluated with various models based on two ephemerides, two atomic time scales and two TT—TB time transformations. Comparisons are carried out with results from other programs. We provide evidence that systematic errors induced by the model adopte...

The authors briefly present two pulsar observation projects that were undertaken at the National Radio Astronomical Observatory: (1) a campaign of multi-frequency observations of four millisecond pulsars using the newly developped spectral processor at the Green-Bank radio observatory that enabled to determine the fluxes of these pulsars at a numbe...

A new analysis of the timing data acquired on the fast pulsar PSR1937+214 is presented. Parameters are evaluated with various models based on two ephemerides, two atomic time scales and two TT—TB time transformations. Comparisons are carried out with results from other programs. We provide evidence that systematic errors induced by the model adopte...

Les données de haute précision de chronométrage des pulsars rapides vont contribuer significativement à l'astrophysique des étoiles à neutrons, à la dynamique du système solaire, à l'astrométrie, à la métrologie du temps et à la cosmologie. Deux années de données de chronométrage du pulsar rapide PSR1937+214 ont été analysées afin de déterminer d'é...

An analytical formula for the time transformation TB-TT valid over a few thousand years around J2000.0 has been computed with an accuracy at the 1 ns level. The numerical and analytical procedures to compute this transformation are discussed and compared.

An analytical formula for the time transformation TDB–TDT valid over a few thousand years around J2000 has been computed with an accuracy at the 1 ns level. The coefficients for a formula accurate at the 100 ns level are provided here. The numerical and analytical procedures to compute this transformation are discussed. We note that these procedure...

The first two years of timing data of the fast pulsar PSR 1937+214 from Arecibo have been analysed with a new program developped at the Bureau des Longitudes. The author has reduced these data with different ephemerides and atomic time scales. He thus has noticed systematic errors in the pulsar parameters determined with these different theories. T...

A collection of 4411 observations of occultations of Jupiter's Galilean satellites, obtained between 1836 and 1972, have been reduced to UT time scale and compared to predictions arising from three current theories. The method for obtaining time residuals, the differences between the observed and predicted values, is described. Although the present...

An analytical formula for the time transformation TDB-TDT valid over a few thousand years around J2000 has been computed with an accuracy at the 1 ns level. The analytical theories ELP2000 and VSOP82 developed at the Bureau des Longitudes were used for the motions of the solar system bodies.

Historic occultation data on Galilean satellites were evaluated for usefulness for determining the proper motions of the satellites in conjunction with current, higher accuracy data. The database covers 4411 observations from 1836-1972 and includes observations from 44 different sites. The time residuals were calculated by two techniques which cons...