Aude Lemonsu

CNRS / Météo-France, Toulouse, France · National Center for Meteorological Research, CNRM, UMR 3589

Accurately predicting weather and climate in cities is critical for safeguarding human health and strengthening urban resilience. Multimodel evaluations can lead to model improvements; however, there have been no major intercomparisons of urban‐focussed land surface models in over a decade. Here, in Phase 1 of the Urban‐PLUMBER project, we evaluate...

Understanding the cooling service provided by vegetation in cities is important to inform urban policy and planning. However, the performance of decision-support tools estimating heat mitigation for urban greening strategies is not systematically evaluated. Here, we develop a calibration algorithm and evaluate the performance of the Urban Cooling m...

Since a decade, convection-permitting regional climate models (CPRCM) have emerged showing promising results, especially in improving the simulation of precipitation extremes. In this article, the CPRCM CNRM-AROME developed at the Centre National de Recherches Météorologiques (CNRM) since a few years is described and evaluated using a 2.5-km 19-yea...

The convection-permitting regional climate model CNRM-AROME was applied on a spatial domain restricted to the northern half of France for analyzing its performances in simulating the urban climate of Paris region, and its potential added value compared to the regional climate model CNRM-ALADIN. In addition to its fine horizontal resolution (2.5 km...

La modélisation atmosphérique à très fine échelle permet d'analyser la dynamique de l'îlot de chaleur urbain en contexte de topographie complexe. Deux simulations (Urbaine et Non-Urbaine) mettent en évidence les effets associés à l'urbanisation. La taille des agglomérations, dans le cas de Lyon et Grenoble, n'influence pas la différence de températ...

Cities develop a specific climate related to their morphology and the materials that constitute them. The addition of vegetation in urban areas induces cooling and shading effects that can modify local climate and thermal comfort conditions. The Town Energy Balance (TEB) urban canopy model offers several configurations for a more or less fine-tuned...

The convection-permitting regional climate model CNRM-AROME was applied on a spatial domain restricted to the northern half of France for analyzing its performances in simulating the urban climate of Paris region, and its potential added value compared to the regional climate model CNRM-ALADIN. In addition to its fine horizontal resolution (2.5 km...

Since a decade, convection-permitting regional climate models (CPRCM) have emerged showing promising results, especially in improving the simulation of precipitation extremes. In this article, the CPRCM CNRM-AROME developed at the Centre National de Recherches Météorologiques (CNRM) since a few years is described and evaluated using a 2.5-km long 1...

Several urban canopy models now incorporate urban vegetation to represent local urban cooling related to natural soils and plants evapotranspiration. Nevertheless, little is known about the realism of simulating these processes and turbulent exchanges within the urban canopy. Here, the coupled modelling of thermal and hydrological exchanges was inv...

Nature-based solutions (NBS) are increasingly promoted to mitigate urbanization effects, such as the urban heat island. The release of latent heat requires the availability of water in the urban soils. Models able to represent both detailed water and energy budgets are needed for a reliable evaluation of NBSs performances. The TEB-Hydro model is a...

Approximately 10 years ago, convection‐permitting regional climate models (CPRCMs) emerged as a promising computationally affordable tool to produce fine resolution (1–4 km) decadal‐long climate simulations with explicitly resolved deep convection. This explicit representation is expected to reduce climate projection uncertainty related to deep con...

Cette évaluation de la prise en compte des services écosystémiques dans les décisions d’aménagement urbain s’inscrit dans le cadre global de l’Évaluation française des écosystèmes et des services écosystémiques (Efese). Elle vise à proposer à l’ensemble des acteurs de l’aménagement urbain une démarche d’évaluation sur laquelle s’appuyer pour intégr...

Regional Climate Models (RCMs) are the primary climate information available to public stakeholders and city-planners to support local adaptation policies. However, with resolution in the order of ten kilometres, RCMs do not explicitly represent cities and their influence on local climate (e.g. Urban Heat Island; UHI). Downscaling methods are requi...

In 2003, the city of Paris faced a particularly severe heat wave that resulted in an exceptional excess mortality rate for the urban population. Subsequently, several research projects in partnership with public stakeholders investigated adaptation strategies that could be implemented to address the combined effects of climate change (leading to an...

Cities are particularly vulnerable to extreme weather episodes, which are expected to increase with climate change. Cities also influence their own local climate, for example, through the relative warming known as the urban heat island (UHI) effect. This review discusses urban climate features (even in complex terrain) and processes. We then presen...

Some actions intended to adapt to climate change may do more harm than good, especially when they consume energy, making it more difficult to shift to decarbonized energy, or when, in meeting the needs of one group of people, they increase the vulnerability of others. Heat wave risk provides a typical example: air conditioning (AC) equipment may tr...

Cities are particularly vulnerable to meteorological hazards because of the concentration of population, goods, capital stock and infrastructure. Urban climate services require multi-disciplinary and multi-sectorial approaches and new paradigms in urban climate modelling. This paper classifies the required urban input data for both mesoscale state-...

This article presents a novel methodology for the characterization of tree vegetation phenology, based on vegetation indices time series reconstruction and adapted to urban areas. The methodology is based on a pixel by pixel curve fitting classification, together with a subsequent Savitzky–Golay filtering of raw phenological curves from pixels clas...

The Town Energy Balance (TEB) urban climate model has recently been improved to more realistically address the radiative effects of trees within the urban canopy. These processes necessarily have an impact on the energy balance that needs to be taken into account. This is why a new method for calculating the turbulent fluxes for sensible and latent...

Bien que ce fait soit peu connu, Joël Noilhan a commencé sa carrière non pas dans l'étude de la végétation, mais dans celle du climat urbain. Ses résultats de thèse sur les échanges radiatifs entre les différentes faces d'un bâtiment, le ciel et le sol sont encore utilisés comme hypothèses dans la plupart des modèles de canopée urbaine, comme celui...

Historically, the urban climate and its interaction with regional environment and larger‐scale meteorological phenomena have been studied by comparing weather stations in urban and surrounding rural areas. Nevertheless, spatialized meteorological data are now available with different spatial resolutions, temporal frequencies, and time depths. Here...

Cities are particularly vulnerable to meteorological hazards because of the concentration of population, goods, capital stock and infrastructure. Urban climate services require multidisciplinary and multi-sectorial approaches and new paradigms in urban climate modelling. This paper classifies the required urban input data for both mesoscale state-o...

The TEB urban climate model has recently been improved to more realistically address the radiative effects of trees within the urban canopy. These processes necessarily have an impact on the energy balance that needs to be taken into account. This is why a new method for calculating the turbulent fluxes for sensible and latent heat has been impleme...

Most climate models do not explicitly model urban areas and at best describe them as rock covers. Nonetheless, the very high resolutions reached now by the regional climate models may justify and require a more realistic parameterization of surface exchanges between urban canopy and atmosphere. To quantify the potential impact of urbanization on th...

The EUREQUA project raises the issue of the definition and evaluation of the environmental quality of neighbourhoods. The approach consists of integrating and cross-referencing observable data characterising the physical environment and people’s perception of their quality of life. The study area is a neighbourhood in Toulouse (France) with high so...

Cities modify their local climate, and at the same time they suffer from the local impacts of climate change. Our paper discusses the progress and obstacles in three active research topics that contribute to increasing the capability within the urban climate research community for transferring local climate knowledge to society. The first is linked...

Climate change and demographic pressures are affecting both the urban water balance and microclimate, thus amplifying urban flooding and the urban heat island phenomena. These issues need to be addressed when engaging in urban planning activities. Local authorities and stakeholders have therefore opted for more nature-based adaptation strategies, w...

https://ams.confex.com/ams/ICUC10/meetingapp.cgi/Paper/341062

https://ams.confex.com/ams/ICUC10/meetingapp.cgi/Paper/341586

Climate change and demographic pressure are common issues to be considered when conducting urban planning. Local authorities and stakeholders have therefore opted for more nature-based adaptation strategies, which are especially suitable to influence both hydrological and energy processes. Assessing the multiple benefits of such strategies on the u...

The study of urban climates now represents a full scientific field on its own. The 9th International Conference on Urban Climate (ICUC-9), held in July 2015 in Toulouse, France, provided a recent forum for urban climate scientists to share the results of their research. This introduction paper presents the 20 articles of this special issue. They ar...

doi: 10.1175/BAMS-D-17-0106.1

Cities are confronted to demographic pressure and climate change issues, influencing the life quality, comfort and energy costs. Facing these changes, the understanding of hydrological and energy processes in cities has become essential to future management strategies. However, studies dedicated to urban environment generally represent these proces...

The Town Energy Balance (TEB) model has been refined and improved in order to explicitly represent street trees and their impacts on radiative transfer: a new vegetated stratum on the vertical plane, which can shade the road, the walls, and the low vegetation has been added. This modification led to more complex radiative calculations, but has been...

Increasing heat-wave risk due to regional climate evolutions, exacerbated by urban heat island (UHI) effects, is a major threat for the inhabitants of many cities. Adaptive policies such as greening the urban environment are often proposed to limit population vulnerability, as vegetation enables to regulate the microclimate by evapotranspiration. T...

The TEB model has been refined and improved in order to explicitly represent street trees and their impacts on radiative transfers: a new vegetated stratum on the vertical plane, which can superimpose to road and low vegetation has been added. This modification has obviously complexified the radiative calculations, but has been done with a concern...

The evolution of heat-wave risk in cities is related to regional climate change in interaction with urban heat island. Land planning and urban transport policies, due to their long-lasting impact on city’s size and shape, can also have an influence. However, these combined effects are complex and strongly depend on the indicators used to quantify h...

The MApUCE project aims to integrate in urban policies and most relevant legal documents quantitative data from urban microclimate, climate and energy. The primary objective of this project is to obtain climate and energy quantitative data from numerical simulations, focusing on urban microclimate and building energy consumption in the residential...

Cet article analyse les impacts obser- vés et projetés du changement clima- tique sur les systèmes humains et naturels, leur vulnérabilité et les pos- sibilités d’adaptation. Il donne un aperçu des principaux résultats pour l’hydrologie, l’agriculture, les écosys- tèmes naturels, les infrastructures, le transport, l’énergie, le tourisme, la santé e...

Societies have to both reduce their greenhouse gas emissions and undertake adaptation measures to limit the negative impacts of global warming on the population, the economy and the environment. Examining how best to adapt cities is especially challenging as urban areas will evolve as the climate changes. Thus, examining adaptation strategies for c...

Urban population is growing and will still increase in the future. Urbanisation modifies both local climate and water cycle. Introduction of vegetation in cities is supposed to be a solution to limit the urbanisation impacts by increasing water infiltration and favoring evapotranspiration. In the framework of the VegDUD project, different greening...

We analysed the temporal evolution of heat wave frequency in the Paris region in a changing future climate (1960-1989,2020-2049,2070-2099). Firstly, a method for extracting heat waves from observed or simulated time series of daily minimum and maximum temperatures was proposed, based on heat-impact considerations. It was evaluated over the period 1...

The production of solar energy in cities is clearly a way to diminish our dependency to fossil fuels, and is a good way to mitigate global warming by lowering the emission of greenhouse gases. However, what are the impacts of solar panels locally? To evaluate their influence on urban weather, it is necessary to parameterize their effects within the...

Dense city, green city, realistic gamble?The role of vegetation in sustainable urban development: an approach by the climatic, hydrologic, energy and ambiances stakes.Urban sprawl increases the artificial surfaces to the detriment of natural ones. However, with the increase of urban population it is necessary to find compromises, and introducing mo...

SURFEX is a new externalized land and ocean surface platform that describes the surface fluxes and the evolution of four types of surfaces: nature, town, inland water and ocean. It is mostly based on pre-existing, well-validated scientific models that are continuously improved. The motivation for the building of SURFEX is to use strictly identical...

The need to prepare cities for climate change adaptation requests the urban modeller community to implement sustainable adaptation strategies within their models to be tested against specific city morphologies and scenarios. Greening city roofs is part of these strategies. In this context, the GREENROOF module for TEB (town energy balance) has been...

The need to prepare cities for climate change adaptation requests the urban modeller community to implement within their models sustainable adaptation strategies to be tested against specific city morphologies and scenarios. Greening city roofs is part of these strategies. In this context, a GREENROOF module for TEB (Town Energy Balance) has been d...

A consequence of urban heat islands in summer is an increase in the use of air conditioning in urbanized areas, which while cooling the insides of buildings, releases waste heat to the atmosphere. A coupled model consisting of a meso-scale meteorological model (MESO-NH) and an urban energy balance model (TEB) has been used to simulate and quantify...

Cities impact both local climate, through urban heat islands and global climate, because they are an area of heavy greenhouse gas release into the atmosphere due to heating, air conditioning and traffic. Including more vegetation into cities is a planning strategy having possible positive impacts for both concerns. Improving vegetation representati...

SURFEX is a new externalized land and ocean surface platform that describes the surface fluxes and the evolution of four types of surface: nature, town, inland water and ocean. It can be run either coupled or in offline mode. It is mostly based on pre-existing, well validated scientific models. It can be used in offline mode (from point scale to gl...

The EPICEA project is a joint collaboration between the City of Paris, the French Meteorological Office (Meteo-France) and the French Scientific and Technical Centre for Building. The general objective is to quantify the impact of climate change over the city of Paris as well as the influence of the built environment on urban climate. The project t...

Cities impact both local climate, through urban heat islands, and global climate, because they are an area of heavy greenhouse gas release into the atmosphere due to heating, air conditioning and traffic. Including more vegetation into cities is a planning strategy having possible positive impacts for both concerns. Improving vegetation representat...