Alexandre Cauquoin

Alexandre Cauquoin
The University of Tokyo | Todai · Institute of Industrial Science

PhD

About

52
Publications
7,745
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271
Citations
Introduction
My name is Alexandre Cauquoin. I study the past changes of Earth climate by using isotopic species like stable water isotopes (H216O, H218O and HDO), tritium or beryllium-10 under a model-data approach. I am specialised in the implementation and modelling of these isotopic species in General Circulation Models (GCMs), which allow to better understand the interactions between the different compartments of our climate system and to make projections of future climates for IPCC reports.
Additional affiliations
April 2022 - present
The University of Tokyo
Position
  • Assistant Professor
September 2021 - March 2022
The University of Tokyo
Position
  • PostDoc Position
August 2019 - August 2021
The University of Tokyo
Position
  • PostDoc Position
Description
  • FY2019-2020 JSPS Postdoctoral Fellowship for Research in Japan Award (Standard)
Education
October 2010 - September 2013
Université Paris-Sud 11
Field of study
  • Paleoclimate and natural archives
September 2008 - June 2010
Université Paris-Sud 11
Field of study
  • Physics and Environment
September 2005 - June 2008
Université Paris-Sud 11
Field of study
  • Fundamental Physics

Publications

Publications (52)
Article
Full-text available
We present here the first results, for the pre-industrial and mid-Holocene climatological periods, of the newly developed isotope-enhanced version of the fully coupled Earth system model MPI-ESM, called hereafter MPI-ESM-wiso. The water stable isotopes H216O, H218O and HDO have been implemented into all components of the coupled model setup: the at...
Article
The isotopic composition of oxygen (δ ¹⁸ O), and hydrogen (δ ² H) are widely used to locate the geographical origin of biological remains or manufactured products. In this paper, we analyze the distributions of δ ¹⁸ O and δ ² H in tap waters sampled across France, and in precipitation interpolated with OIPC and modelled with the isotope-enabled ECH...
Article
Full-text available
We present here results of new isotope-enabled simulations with an enhanced ECHAM6-wiso model version nudged to the ERA5 reanalyses, at two different spatial resolutions, for the period 1979-2018. The isotopic content of snow on sea ice is considered, yielding surface water vapor with lower isotope ratios over sea ice covered areas, and the kinetic...
Article
Full-text available
Water isotopes measured in Antarctic ice cores enable reconstruction at the first order of the past temperature variations. However, the seasonality of the precipitation and episodic events, including synoptic-scale disturbances, influence the isotopic signals recorded in ice cores. In this study, we adopted an isotope-enabled atmospheric general c...
Article
Full-text available
Succession of cold glacials and warm interglacials during the Quaternary results from large global climate responses to variable orbital configurations, accompanied by fluctuating greenhouse gas concentrations. Despite the influences of sea ice and atmospheric and ocean circulations in the Southern Ocean on atmospheric CO2 concentrations and climat...
Book
Full-text available
Past environments of the Earth's surface may be deciphered and modelled using stable isotopes along with mineralogical, sedimentological, biological, palaeontological, chemical and climatological methodologies. This volume is devoted to studies investigating the distribution of stable isotopes in precipitation and groundwaters and their interaction...
Preprint
Full-text available
The description of the hydrological cycle in Atmospheric General Circulation Models (GCMs) can be validated using water isotopes as tracers. Many GCMs now simulate the movement of the stable isotopes of water, but here we present the first GCM simulations modelling the content of natural tritium in water. These simulations were obtained using a ver...
Preprint
Full-text available
Atmospheric general circulation models (AGCMs) are known to have a warm and isotopically enriched bias over Antarctica. We test here the hypothesis that these biases are partly consequences of a too diffusive advection. Exploiting the LMDZ-iso model, we show that a less diffusive representation of the advection, especially on the horizontal, is ver...
Article
Full-text available
In order to investigate the impact of spatial resolution on the discrepancy between simulated δ18O and observed δ18O in Greenland ice cores, regional climate simulations are performed with the isotope-enabled regional climate model (RCM) COSMO_iso. For this purpose, isotope-enabled general circulation model (GCM) simulations with the ECHAM5-wiso ge...
Preprint
Full-text available
Abstract. In this study, regional climate simulations under present-day and mid-Holocene conditions are performed with an isotope-enabled RCM for Greenland. The capability of the applied isotope-enabled Regional Climate Model (RCM), COSMO_iso, to reproduce observed isotopic ratios in Greenland for these two periods is investigated by downscaling gl...
Article
Full-text available
We present here the first results, for the preindustrial and mid-Holocene climatological periods, of the newly developed isotope-enhanced version of the fully coupled Earth system model MPI-ESM, called hereafter MPI-ESM-wiso. The water stable isotopes H216O, H218O and HDO have been implemented into all components of the coupled model setup. The mid...
Article
Atmospheric general circulation models (AGCMs) are known to have a warm and isotopically enriched bias over Antarctica. We test here the hypothesis that these biases are partly consequences of a too diffusive advection. Exploiting the LMDZ-iso model, we show that a less diffusive representation of the advection, especially on the horizontal, is ver...
Article
Full-text available
All types of applications of stable water isotopes, for example, for the reconstruction of paleotemperatures or for climate model validation, rely on a proper understanding of the mechanisms determining the isotopic composition of water vapor and precipitation. In this study, we use the isotope-enabled limited-area model COSMOiso to characterize th...
Poster
Full-text available
The hydrological cycle is a fundamental component of the Earth’s climate system. Modeling the time response of this cycle and the implied physical processes challenges the general circulation models (GCM) used to study the climate system and to project future climate. Water stable isotopes (H216O, H218O and HD16O) are integrated tracers of climate...
Article
Full-text available
Better assessing the dynamic of stratosphere‐troposphere exchange is a key point to improve our understanding of the climate dynamic in the East Antarctica Plateau, a region where stratospheric inputs are expected to be important. Although tritium (3H or T), a nuclide naturally produced mainly in the stratosphere and rapidly entering the water cycl...
Article
Full-text available
Atmospheric general circulation models (AGCMs) are known to have a warm and isotopically enriched bias over Antarctica. We test here the hypothesis that these biases are consequences of a too diffusive advection. Using the LMDZ-iso model, we show that a good representation of the advection, especially on the horizontal, is very important to reduce...
Poster
Full-text available
We present here the first results for present-day conditions of the ongoing implementation of water stables isotopes in the latest version of the ECHAM atmospheric general circulation model, ECHAM6, enhanced by the JSBACH interactive land surface scheme (ECHAM6-wiso). Major changes with respect to its predecessor ECHAM5 have to do with the treatmen...
Data
High-resolution 10Be concentrations in the NGRIP, EDC, EDML and Vostok ice cores and high-resolution dD data in Vostok (5G) during the Laschamp excursion
Article
Full-text available
Using new high-resolution ¹⁰Be measurements in the NGRIP, EDML and Vostok ice cores, together with previously published data from EDC, we present an improved synchronization between Greenland and Antarctic ice cores during the Laschamp geomagnetic excursion ∼ 41 kyr ago. We estimate the precision of this synchronization to be ±20 years, an order of...
Article
Full-text available
Improving the representation of the hydrological cycle in Atmospheric General Circulation Models (AGCMs) is one of the main challenges in modeling the Earth's climate system. One way to evaluate model performance is to simulate the transport of water isotopes. Among those available, tritium (HTO) is an extremely valuable tracer, because its content...
Article
Full-text available
Using new high resolution 10Be measurements in the NGRIP, EDML and Vostok ice cores, together with previously published data from EDC, we present an improved synchronization between Greenland and Antarctic ice cores 20 during the Laschamp geomagnetic excursion ~41 ky ago. We estimate the precision of this synchronization to be ± 20 years, an order...
Poster
Atmospheric water in form of vapor or clouds is responsible for ~75% of the natural greenhouse effect and carries huge amounts of latent heat. For this reason, a best possible description of the hydrological cycle is a prerequisite for reliable climate modelling. As the stable isotopes H216O, H218O and HDO differ in vapor pressure, they are fractio...
Article
Full-text available
Water isotopes are commonly used for climate reconstruction from ice cores. The different heavy isotopes of water such as H218O, H217O or HDO give information about local temperature but also temperature and humidity of water vapour sources. Quantification of these parameters relies on the good knowledge of equilibrium and kinetic isotopic fraction...
Data
Improving the representation of the hydrological cycle in Atmospheric General Circulation Models (AGCMs) is one of the main challenges in modeling the Earth's climate system. One way to evaluate model performance is to simulate the transport of water isotopes. Among those available, tritium (HTO) is an extremely valuable tracer, because its content...
Conference Paper
Full-text available
Water stable isotopes (H216O, H218O, HDO, H217O) are well-known tracers of the past and present-day hydrological cycle. In contrast, in spite of the global monitoring of its concentration in precipitation (IAEA database) and a substantial dataset concerning polar ice ([1] and references therein) tritium (HTO) has received little attention so far in...
Article
Full-text available
Ice cores are exceptional archives which allow us to reconstruct a wealth of climatic parameters as well as past atmospheric composition over the last 800 kyr in Antarctica. Inferring the variations in past accumulation rate in polar regions is essential both for documenting past climate and for ice core chronology. On the East Antarctic Plateau, t...
Article
Full-text available
Ice cores are exceptional archives which allow us to reconstruct a wealth of climatic parameters as well as past atmospheric composition over the last 800 ka in Antarctica. Inferring the variations of past accumulation rate in polar regions is essential both for documenting past climate and for ice core chronology. On the East Antarctic plateau, th...
Article
Full-text available
Context. Abreu et al. (2012, A&A.; 548, A88) have recently compared the periodicities in a 14C - 10Be proxy record of solar variability during the Holocene and found a strong similarity with the periodicities predicted on the basis of a model of the time-dependent torque exerted by the planets on the sun's tachocline. If verified, this effect would...
Article
Full-text available
The Laschamp excursion is a period of reduced geomagnetic field intensity occurring 40.7 ± 1.0 kyr ago. As a consequence, cosmogenic isotope production increased dramatically and its sensitivity to solar activity was enhanced during this period. The latter occurs because a larger fraction of the lower-energy interstellar galactic cosmic-ray particl...
Thesis
Full-text available
The polar ice cores, in addition to improving our understanding of the climate, give access to beryllium-10 (10Be) fallout, an isotope of cosmogenic origin created by the interaction of Galactic Cosmic Rays with the upper atmosphere. Its production rate depends on the intensity of the primary cosmic rays, which are modulated by solar activity and t...
Article
Full-text available
The polar ice cores, in addition to improving our understanding of the climate, give access to beryllium-10 (10Be) fallout, an isotope of cosmogenic origin created by the interaction of Galactic Cosmic Rays with the upper atmosphere. Its production rate depends on the intensity of the primary cosmic rays, which are modulated by solar activity and t...
Article
Full-text available
Correct estimation of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice core studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: outputs of a firn densification model, and measurements of δ15N of N2 in air trapped in ice core, assuming th...
Article
Full-text available
Correct estimate of the firn lock-in depth is essential for correctly linking gas and ice chronologies in ice cores studies. Here, two approaches to constrain the firn depth evolution in Antarctica are presented over the last deglaciation: output of a firn densification model and measurements of δ15N of N2 in air trapped in ice core. Since the firn...
Conference Paper
Full-text available
Polar ice cores and marine sediments are two of the most important sources of paleoclimate records. The optimum exploitation of these records requires that they be put on a common chronology. One possible parameter which can be used to do this is the geomagnetic field intensity. The last decade has seen a large increase in the number of relative pa...
Conference Paper
Full-text available
Beryllium-10 is a long-lived cosmogenic radionuclide (half-life of 1.39 Myr) induced by nuclear interactions between Galactic Cosmic Rays (GCR, high-energy charged particles and their secondary products) and the upper atmosphere (nitrogen and oxygen). The flux of GCR on Earth is inversely related to the solar activity (induced interplanetary magnet...
Conference Paper
Full-text available
The atmospheric ratio 14C/C depends on two factors: (i) cosmogenic production, influenced by solar activity and geomagnetic field, (ii) carbon distribution in the atmosphere, biosphere and oceans. Around 40 000 years ago the calibration curve remains uncertain due to the low 14C/C ratio, uncertain reservoir effects, and the limited number of measur...

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Projects

Projects (2)
Project
We plan to reconstruct the link between climate, water cycle and sratospheric input over the past 100 years in Antarctica using all water isotopes (dD, d18O, d17O, T) and 10Be in an approach combining data and model.
Project
PalMod WP3.3 TP1: Implementation of water isotopes in the fully coupled model MPI-ESM PalMod is funded by the Federal Ministry of Education and Science (BMBF) to understand climate system dynamics and variability during the last glacial cycle. Specific topics are: - to identify and quantify the relative contributions of the fundamental processes which determined the Earth’s climate trajectory and variability during the last glacial cycle, - to simulate with comprehensive Earth System Models (ESMs) the climate from the peak of the last interglacial (the Eemian warm period) up to the present, including the changes in the spectrum of variability, and - to assess possible future climate trajectories beyond this century during the next millennia with sophisticated ESMs tested in such a way. The envisioned approach is innovative in three respects. First, the consortium aims at simulating a full glacial cycle in transient mode and with comprehensive ESMs which allow full interactions between the physical and biogeochemical components of the Earth system, including ice sheets. Second, we shall address climate variability during the last glacial cycle on a large range of time scales, from interannual to multi-millennial, and attempt to quantify the relative contributions of external forcing and processes internal to the Earth system to climate variability at different time scales. Third, in order to achieve a higher level of understanding of natural climate variability at time scales of millennia, its governing processes and implications for the future climate, we bring together three different research communities: the Earth system modeling community, the proxy data community and the computational science community.