F. Couvreux

F. Couvreux
French National Centre for Scientific Research | CNRS · Météo-France

About

126
Publications
24,781
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,345
Citations

Publications

Publications (126)
Article
Full-text available
A severe heatwave occurred in April 2010 over West Africa. It was characterised by a particularly high daily minimum temperature reaching more than 35°C locally and a high water vapour content. In this study we analyse the ability of a mesoscale limited area model to represent such an event and investigate the advantage of using an explicit represe...
Article
This study evaluates the ability of the French Convection‐Permitting model AROME‐OM to represent shallow cumulus and their main organisations for boreal winter conditions in the North Atlantic trades. It uses a set of three winter seasons (January‐February 2018‐2020) of high‐resolution (1.3 and 2.5 km) simulations over the Caribbean domain (9.7‐22....
Preprint
Full-text available
Traditional general circulation models, or GCMs -- i.e. 3D dynamical models with unresolved terms represented in equations with tunable parameters -- have been a mainstay of climate research for several decades, and some of the pioneering studies have recently been recognized by a Nobel prize in Physics. Yet, there is considerable debate around the...
Article
Trade wind cumulus clouds have a significant impact on the Earth's radiative balance due to their ubiquitous presence and significant coverage in subtropical regions. Many numerical studies and field campaigns have focused on better understanding the thermodynamic, microphysical, and macroscopic properties of cumulus clouds with ground-based and sa...
Article
Full-text available
Drones are commonly used for civil applications and are accessible to those with limited piloting skills in several scenarios. However, the deployment of a fleet in the context of scientific research can lead to complex situations that require an important preparation in terms of logistics, permission to fly from authorities, and coordination durin...
Article
Full-text available
Clouds are largely responsible for the spread of climate models predictions. Here we focus on the uncertainties in cloud shortwave radiative effect due to the parameterization of liquid cloud single scattering properties (SSPs) from liquid water content (LWC) and droplet number concentration (N), named parameterization of cloud optical properties....
Article
Full-text available
I n an enthusiastic paper 20 years ago, R. A. Brown suggested that remote sensing measurements of the ocean surface reaching resolutions of ten to hundreds of meters over 1000-km regions would open a new realm for analysis, modelling, and understanding of the atmospheric and oceanic boundary layers (Brown 2000). Twenty years later, it is too early...
Article
The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our abi...
Article
Full-text available
This paper makes use of spaceborne observational data sets in order to characterize radiative processes involved in spring time heat waves in the Sahel. Spring corresponds to the hottest period of the year, with a high aerosol load, a gradual moistening, and the presence of clouds contributing to greenhouse effect. Heat waves are defined as synopti...
Article
Full-text available
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...
Article
jats:p>Abstract. The science guiding the EUREC4A campaign and its measurements are presented. EUREC4A comprised roughly five weeks of measurements in the downstream winter trades of the North Atlantic – eastward and south-eastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a tu...
Article
Full-text available
Process‐scale development, evaluation, and calibration of physically based parameterizations of clouds and radiation are powerful levers for improving weather and climate models. In a series of papers, we propose a strategy for process‐based calibration of climate models that uses machine learning techniques. It relies on systematic comparisons of...
Chapter
The evolution of cumulus clouds is still no fully understood by atmospheric scientists [1].
Article
Full-text available
Abstract The development of parameterizations is a major task in the development of weather and climate models. Model improvement has been slow in the past decades, due to the difficulty of encompassing key physical processes into parameterizations, but also of calibrating or “tuning” the many free parameters involved in their formulation. Machine...
Article
Full-text available
Abstract The representation of stable boundary layers (SBLs) still challenges turbulence parameterizations implemented in current weather or climate models. The present work assesses whether these model deficiencies reflect calibration choices or intrinsic limits in currently‐used turbulence parameterization formulations and implementations. This q...
Preprint
Full-text available
Trade wind cumulus clouds have a significant impact on the earth's radiative balance, due to their ubiquitous presence and significant coverage in subtropical regions. Many numerical studies and field campaigns have focused on better understanding the thermodynamic and macroscopic properties of cumulus clouds with ground-based and satellite remote...
Article
A modelling case study based on observations from the Dynamics of the Madden‐Julian Oscillation field campaign is presented and discussed. It aims at investigating the ocean‐atmosphere coupling and the marine atmospheric boundary layer structure over an oceanic diurnal warm layer. This case corresponds to the development of a diurnal warm layer cha...
Preprint
Full-text available
The science guiding the EUREC4A campaign and its measurements are presented. EUREC4A comprised roughly five weeks of measurements in the downstream winter trades of the North Atlantic – eastward and south-eastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in ou...
Article
Full-text available
This article is part of the special issue “Elucidating the role of clouds–circulation coupling in climate:datasets from the 2020 (EUREC4A) field campaign”. It is not associated with a conference.
Article
Full-text available
In polar regions, where the boundary layer is often stably stratified, atmospheric models produce large biases depending on the boundary-layer parametrizations and the parametri-zation of the exchange of energy at the surface. This model intercomparison focuses on the very stable stratification encountered over the Antarctic Plateau in 2009. Here,...
Article
Full-text available
Significance The SADA is an annually-resolved hydroclimate atlas in South America that spans the continent south of 12°S from 1400 to 2000 CE. Based on 286 tree ring records and instrumentally-based estimates of soil moisture, the SADA complements six drought atlases worldwide filling a geographical gap in the Southern Hemisphere. Independently val...
Article
Full-text available
North Africa experienced a severe heatwave in April 2010 with daily maximum temperatures (\(T_{max}\)) frequently exceeding \(40\,^{\circ }\mathrm{C}\) and daily minimum temperatures (\(T_{min}\)) over \(27\,^{\circ }\mathrm{C}\) for more than five consecutive days in extended Saharan and Sahelian areas. Observations show that areas and periods aff...
Article
Full-text available
Abstract The representation of stratocumulus clouds, and of the stratocumulus to cumulus transitions which are ubiquitous features of marine boundary layer clouds, remains a challenge for climate models. We show how a mass flux representation of boundary layer convective structures combined with an eddy diffusivity scheme, the “thermal plume model,...
Article
Full-text available
Abstract Interactions between clouds and radiation are at the root of many difficulties in numerically predicting future weather and climate and in retrieving the state of the atmosphere from remote sensing observations. The broad range of issues related to these interactions, and to three‐dimensional interactions in particular, has motivated the d...
Article
Full-text available
Plain Language Summary The representation of marine stratocumulus remains significantly biased in climate models, which lead to important uncertainties in the simulation of the present‐day climate and in projections of future climate change. These errors are related to the way boundary‐layer clouds are represented through empirically defined parame...
Preprint
Full-text available
Interactions between clouds and radiation are at the root of many difficulties in numerically predicting future weather and climate and in retrieving the state of the atmosphere from remote sensing observations. The large range of issues related to these interactions, and in particular to three-dimensional interactions, motivated the development of...
Poster
Full-text available
The semi-arid Sahelian region is particularly prone to wind erosion due to low and variable annual precipitation producing low vegetation cover with a high interannual variability. Surfaces traditionally devoted to livestock grazing are used as croplands, increasing the proportion of bare surface unprotected from wind erosion. Wind erosion could si...
Article
Full-text available
Many general circulation models (GCMs) assume some heterogeneity of water amounts in their grid boxes and use probability density functions to parameterize cloud fractions CF and amounts of condensed water qc. Most GCM cloud schemes calculate the CF as the volume of the grid box that contains clouds (CFvol), whereas radiative fluxes primarily depen...
Article
Full-text available
This paper presents the Meso-NH model version 5.4. Meso-NH is an atmospheric non hydrostatic research model that is applied to a broad range of resolutions, from synoptic to turbulent scales, and is designed for studies of physics and chemistry. It is a limited-area model employing advanced numerical techniques, including monotonic advection scheme...
Article
Full-text available
The hydroxyl radical (OH) is a highly reactive species and plays a key role in the oxidative capacity of the atmosphere. We explore the potential impact of a convective boundary layer on reconciling the calculation–measurement differences for OH reactivity (the inverse of OH lifetime) attributable to the segregation of OH and its reactants by therm...
Article
Full-text available
This paper presents the Meso-NH model version 5.4. Meso-NH is an atmospheric non hydrostatic research model that is applied to a broad range of resolutions, from synoptic to turbulent scales, and is designed for studies of physics and chemistry. It is a limited-area model employing advanced numerical techniques, including monotonic advection scheme...
Article
Mid-level clouds, located between 2 and 9 km height, are ubiquitous in the tropical belt. However, few studies have documented their characteristics and tried to identify the associated thermodynamical properties, in particular in West Africa. This region is characterized by a strong seasonality with precipitation occurring in the Sahel from June t...
Article
Full-text available
The hydroxyl radical (OH) is a highly reactive specie and plays a key role in the oxidative capacity of the atmosphere. The total OH reactivity, corresponding to the inverse of OH lifetime, may have a significant fraction non-attributable to commonly measured compounds. The turbulence-driven segregation of OH and its reactants can cause substantial...
Article
Full-text available
In the Sahel very high temperatures prevail in spring, but little is known about heat waves in this region at that time of year. This study documents Sahelian heat waves with a new methodology that allows selecting heat waves at specific spatiotemporal scales and can be used in other parts of the world. It is applied separately to daily maximum and...
Article
Full-text available
We present a new diagnostic mixing length for a turbulence scheme based on a prognostic equation for the turbulence kinetic energy. The formulation adds a local vertical wind shear term to the non-local buoyancy-based mixing length currently used in the research mesoscale model Meso-NH. The combined effects better represent local mixing for stably...
Article
Full-text available
In this study we explore a new way to model sub-grid turbulence using particle systems. The ability of particle systems to model small-scale turbulence is evaluated using high-resolution numerical simulations. These high-resolution data are averaged to produce a coarse-grid velocity field, which is then used to drive a complete particle-system-base...
Article
Full-text available
A cloud-resolving model (CRM) allows performing numerical simulations of convective clouds, such as shallow cumulus and stratocumulus, or storms and squall-lines with a resolution on the order of a few tens of metres to a few kilometres over a limited-area 4D (time and space) domain. The development of such models over the past decades is reviewed...
Article
This study analyses the role of breeze circulations induced by a surface sensible heat flux heterogeneity on deep convection initiation. Large-eddy simulations are used to disentangle the processes at play in a typical case of daytime triggering of deep convection over a semi arid land. We show that the presence of a realistic surface sensible heat...
Article
Full-text available
This study presents the first deployment in field campaigns of a balloon-borne turbulence probe, developed with a sonic anemometer and an inertial motion sensor suspended below a tethered balloon. This system measures temperature and horizontal and vertical wind at high frequency and allows the estimation of heat and momentum fluxes as well as turb...
Article
Full-text available
This study evaluates the ability of three operational models, with resolution varying from 2.5 to 16 km, to predict the boundary-layer turbulent processes and mesoscale variability observed during the Boundary Layer Late-Afternoon and Sunset Turbulence (BLLAST) field campaign. We analyse the representation of the vertical profiles of temperature an...
Article
Full-text available
The grey zone of dry convection is the range of scales in which boundary-layer thermals are partly explicitly resolved by numerical weather prediction (NWP) models and partly parametrized. We seek to determine how thermals are divided into subgrid and resolved scales in the grey zone of convective boundary-layer thermals. Reference data for grid-sc...
Presentation
Full-text available
The 4th inter-comparison case (GABLS4) aims to study: the interaction between the boundary layer and the surface in strong stability and the decrease of the turbulence during the diurnal transition. This exercise is being conducted in collaboration with the GEWEX Panel on Global Atmospheric Study (GASS) and the Global Land Atmosphere System Study (...
Article
In this study we use optical ALOS AVNIR-2 and PRISM satellite images to map and inventory glaciers as well as active, inactive and fossil rock glaciers in the Volcán Domuyo region (36°16' S-36°54' S), located in the northwestern tip of the Neuquén Province in Argentina. The area is termed "Transition Cordillera" since it lies between the southernmo...
Article
Full-text available
This study evaluates the ability of three operational models, AROME, ARPEGE and ECMWF, to predict the boundary-layer turbulent processes and mesoscale variability observed during the Boundary Layer Late-Afternoon and Sunset Turbulence (BLLAST) field campaign. AROME is a 2.5 km limited area non-hydrostatic model operated over France, ARPEGE a global...
Article
Full-text available
In this study we explore a new way to model sub-grid turbulence using particle systems. The ability of particle systems to model small scale turbulence is evaluated using high resolution numerical simulations. These high-resolution simulations have been performed with the research atmospheric model Meso-NH and averaged at larger scale from which a...
Article
Full-text available
This study presents the first deployment of a turbulence probe below a tethered balloon in field campaigns. This system allows to measure turbulent temperature fluxes, momentum fluxes as well as turbulent kinetic energy in the lower part of the boundary layer. It is composed of a sonic thermoanemometer and inertial motion sensor. It has been validated...