LOA - Laboratoire d'Optique Atmosphèrique - UMR 8518

France Centre de recherche public
Accréditation CIR
Contact principal
Téléphone : 33(0)3 20 43 45 32
Mail : direction-loa@univ-lille1.fr
Adresse :
Bât. P5
59655 Villeneuve d'Ascq
France
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Description
(Extrait du site web)
Activité Générale :

L'optique atmosphérique cherche à modéliser la propagation à travers l'atmosphère de la lumière visible reçue du soleil et de la lumière infrarouge émise par l'ensemble des surfaces et de l'atmosphère terrestres. Les travaux menés au LOA dans ce domaine s'insèrent dans l'étude globale du climat.

Un premier objectif est de quantifier le rôle de ce rayonnement visible et infrarouge dans les échanges énergétiques de la planète, en particulier de préciser le rôle des nuages dans le bilan radiatif de la terre dont ils constituent un facteur essentiel.

Un second axe de recherche porte sur la caractérisation à l'échelle du globe de différents paramètres qui sont en relation directe avec l'évolution climatique (nuages, aérosols, surfaces), en utilisant principalement l'observation satellitaire.
Les travaux menés dans ce contexte mettent en oeuvre:

* La conception de logiciels permettant de simuler le transfert du rayonnement, à l'aide de modèles du système terre - atmosphère.
* L'analyse d'observations acquises par les capteurs satellitaires existants, le plus souvent sous forme d'images traitées sur ordinateur, et la conception d'expériences satellitaires nouvelles.
* La réalisation de campagnes d'observation de terrain, utilisant des appareillages développés par le laboratoire, mis en oeuvre au sol ou à partir d'avions ou de ballons stratosphériques, et destinés à valider les modèles ou à mettre en évidence les processus atmosphériques.

Le LOA est une unité Mixte de Recherches (UMR/CNRS 8518). Il fait partie de la Fédération de Recherches (FR1818) Milieux naturels et anthropisé Flux et dynamique.

Quelques documents de Laboratoire d'Optique Atmosphèrique
Particles of human origin extinguishing natural solar irradiance in climate systems
PHOENICS
2002 - 2005

Sujets :
Meteorology, Resources of the Sea, Fisheries, Environmental Protection, Forecasting
Participants :
Laboratoire d'Optique Atmosphèrique
Laboratoire d'Optique Atmosphèrique


Laboratoire des Sciences du Climat et de l'Environnement
Laboratoire des Sciences du Climat et de l'Environnement


Institute for Chemistry (otto Hahn Institute)
Institute for Chemistry (otto Hahn Institute)


Institute for Meteorology
Institute for Meteorology


UNIVERSITY OF CRETE HELLAS
UNIVERSITY OF CRETE
Education,Other

DEPARTMENT OF CHEMISTRY - SCHOOL OF SCIENCES ENVIRONMENTAL CHEMICAL PROCESSES LABORATORY Leoforos Knosou, Ampelokipi 71409
HELLAS
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE FRANCE
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Research

URA 0713 - LABORATOIRE D'OPTIQUE ATMOSPHÉRIQUE Laboratoire d'Optique Atmosphérique (URA 713) UER de Physique Fondamentale Université de Lille 59655
FRANCE
UTRECHT UNIVERSITY NEDERLAND
UTRECHT UNIVERSITY
Other,Education

PO Box 80.125 8,HEIDELBERGLAAN 8 3508 TC
NEDERLAND
COMMISSION OF THE EUROPEAN COMMUNITIES ITALIA
COMMISSION OF THE EUROPEAN COMMUNITIES
Research

INSTITUTE FOR ENVIRONMENT AND SUSTAINABILITY ATMOSPHERIC PROCESSES IN GLOBAL CHANGE UNIT Via Enrico Fermi TP 290 21020
ITALIA
NATIONAL RESEARCH COUNCIL OF ITALY ITALIA
NATIONAL RESEARCH COUNCIL OF ITALY
Research,Other

ISTITUTO DI SCIENZE DELL'ATMOSFERA E DEL CLIMA Via P. Gobetti 101 40129
ITALIA
Hide objectives
PHOENICS is a global modelling project to study the direct climate effect of multi-component mixed troposphere aerosols. The potentially great climatic importance of aerosols urgently requires improvement of the estimates of the climate effect of aerosols and better evaluation of the associated uncertainties. Innovative size-resolved simulations of the distribution and properties of the mixture of all major aerosol components will be performed with a global 3-dimensional atmospheric general circulation model to assess the direct effect of aerosols. Several of the main uncertainties associated with this effect will be quantified and reduced by model improvement, comparison to selected observations and optimal use of satellite data. The impact of European emissions on the European and global environment and climate, and the influence of other world regions on Europe will be assessed focusing on the role of the Mediterranean.

Source : Cordis  

Uncertainties in assessing radiative forcing by mineral dust
1998
Auteurs : Y. Balkanski, Yves Balkanski, Olivier Boucher, T. CLAQUIN, T. Claquin et M. Schulz
Masquer le résumé
The assessment of the climatic effects of an aerosol with a large variability like mineral dust requires some approximations whose validity is investigated in this paper. Calculations of direct radiative fordng by mineral dust (short-wave, long-wave and net) are performed with a single-column radiation model for two standard cases in clear sky condition: a desert case and an oceanic case. Surface forcing result from a large diminution of the short-wave fluxes and of the increase in down-welling long-wave fluxes. Top of the atmosphere (TOA) forcing is negative when short-wave backscattering dominates, for instance above the ocean, and positive when short-wave or long-wave absorption dominates, which occurs above deserts. We study here the sensitivity of these mineral forcings to different treatments of the aerosol complex refractive index and size distribution. We also describe the importance of the dust vertical profile, ground temperature, emissivity and albedo. Among these parameters, the aerosol complex refractive index has been identified as a critical parameter given the paucity and the incertitude associated with it. Furthermore, the imaginary part of the refractive index is inadequate if spectrally averaged. Its natural variability (linked to mineralogical characteristics) lead to variations of up to ± 40% in aerosol forcing calculations. A proper representation of the size distribution when modelling mineral aerosols is required since dust optical properties are very sensitive to the presence of small particles. In addition we demonstrate that LW forcing imply a non-negligible sensitivity to the vertical profiles of temperature and dust, the latter being an important constraint for dust effect calculations.
Keywords :
Aerosols ; Atmospheric dust ; Desert ; Radiative properties ; Effect on climate ; Clear sky ; Numerical simulation ; Refraction index ; Particle size distribution ; Sensitivity analysis ; Uncertainty ;
Source : Pascal - INIST  

The Polar Ozone and Aerosol Measurement instrument
1996
Auteurs : R. M. BEVILACQUA, Colette Brogniez, E Chassefière, D-T Chen, F. DALAUDIER, D. J. DEBRESTIAN, C. DENIEL, M.D. Fromm, W. GLACCUM, J. S. HORNSTEIN, R. KREMER, S. S. KRIGMAN, Jacqueline LENOBLE, R. L. LUCKE, J. D. Lumpe, J. J. OLIVERO, C. E. Randall, D W Rusch et E. P. SHETTLE
Masquer le résumé
The second Polar Ozone and Aerosol Measurement instrument (POAM II) is a spaceborne experiment designed to measure the vertical profiles of ozone, water vapor, nitrogen dioxide, aerosol extinction, and temperature in the polar stratosphere and upper troposphere with a vertical resolution of about 1 km. Measurements are made by the solar occultation technique. The instrument package, which has a mass of less than 25 kg, is carried on the Satellite Pour l'Observation de la Terre (SPOT) 3 spacecraft and has a design lifetime of 3-5 years. POAM II has provided data on the south polar ozone hole, north and south polar ozone phenomena, the spatial and temporal variability of stratospheric aerosols and polar stratospheric clouds, and has detected polar mesospheric clouds.
Keywords :
Photometer ; Design ; Data acquisition ; Data analysis ; Vertical profile ; Satellite observation ; Ozone ; Vapor ; Water ; Nitrogen dioxide ; Aerosols ; Atmospheric temperature ; Troposphere ; Stratosphere ; Polar region ; Spaceborne instruments ;
Source : Pascal - INIST  

In situ observation of cirrus scattering phase functions with 22° and 46° halos: Cloud field study on 19 february 1998
2001
Auteurs : Frederique AURIOL, F. Auriol, Gerard BROGNIEZ, Guy FEBVRE, Guy FEBVRE, Jean-Francois GAYET, B. GERARD, Jean-François Gayet, Olivier JOURDAN, Olivier Jourdan, Laurent LABONNOTE et Laurent LABONNOTE
Masquer le résumé
Observations of halos and related phenomena due to ice crystals are commonly reported from ground observations and presented in the literature. Nevertheless, ice crystal characteristics have only been poorly documented from in situ measurements performed in halo-producing cirrus with simultaneous observations of optical phenomena. Using the Polar Nephelometer, a new instrument for in situ measuring of the scattering phase function of cloud droplets and ice particles, 22° and 46° halo features have been evidenced during a cirrus uncinus cloud case study between -30°C and -38°C. Simultaneous microphysical measurements were made with a 2D-C probe manufactured by Particle Measuring Systems Inc. (PMS). The results show that ice crystal properties derived from 2D-C measurements do not present substantial differences when comparing cirrus cloud samples with and without halos. Consequently, the cloud scattering properties appear to be dominated by small ice particles (smaller than about 100 μm), which are poorly documented with conventional PMS probes. The halo occurrences are observed in only a few cloud portions (2%), which are characterized by small horizontal scales (100-400 m). Furthermore, the observed 22° and 46° peak features are smoothed out with regard to modeling results relative to geometric pristine-crystal shape. These differences are discussed by using the new Inhomogeneous Hexagonal Monocrystal theoretical model of light scattering.
Keywords :
Atmospheric halo ; Optical properties ; Aircraft observation ; Light scattering ; Theoretical model ; Crystal form ; Cloud physics ; Case study ; Droplet ; Nephelometer ; Optical observation ; Simultaneous observation ; Measurement in situ ; Ice crystals ; Ice cloud ; Phase function ; Cirrus ;
Source : Pascal - INIST  

Influence of oceanic whitecaps on the global radiation budget
2001
Auteurs : Pierre-Yves Deschamps, Robert J. FROUIN et S. F. LACOBELLIS
Masquer le résumé
Oceanic whitecaps may exert a cooling influence on the planet by increasing surface albedo. The direct, globally averaged radiative forcing due to whitecaps lies in the range 0-0.14 Wm-2 with a probable value of 0.03 Wm-2. Though small, this global value is not negligible compared with the forcing due to some greenhouse gases and anthropogenic aerosols since preindustrial times. The relative importance of whitecaps may be greater on regional and seasonal scales, with radiative forcing values reaching 0.7 Wm-2 in the Indian Ocean during summer. Whitecap effects on surface albedo should be taken into account explicitly in the numerical modeling and analysis of climate change.
Keywords :
Global radiation ; Radiation balance ; Cooling ; Albedo ; Sea surface ; Wind wave ; Radiative properties ;
Source : Pascal - INIST  

Analysis of direct comparison of cloud top temperature and infrared split window signature against independant retrievals of cloud thermodynamic phase
2001
Auteurs : V. GIRAUD, Goloub PHILLIPPE, Jérome RIEDI et O. THOURON
Masquer le résumé
An accurate determination of cloud particle phase is required for retrieval of other cloud properties. The main purpose of this letter is to demonstrate that the cloud phase assumption made in previous cirrus clouds retrievals using infrared split window signatures is not relevant. Coincident observations of the Earth surface from ERS-2 and ADEOS-1 satellites give us the opportunity to compare clouds infrared signatures, as observed by ATSR-2 onboard ERS-2, with cloud thermodynamic phase derived from POLDER onboard ADEOS-1. We find out, firstly, that large Brightness Temperature Differences (BTD), estimated between 11 and 12 μm, may occured for cold liquid water clouds consisting of small supercooled droplets (i.e. altostratus). These BTDs have no longer been attributed to cirrus clouds as previous studies have been. Secondly, the probability to observe ice or water clouds with respect to their cloud top temperature is quantified for our data set. A sharp transition between the ice and water phase is shown for cloud top temperatures ranging between 240 and 260 K. The probability for a cloud to be composed of super-cooled liquid droplets is shown to be higher over land than over ocean. This points out that ice activation susceptibility is more efficient in maritime air mass than in continental one.
Keywords :
Water cloud ; Cirrus ; Earth surface ; Brightness temperature ; Temperature difference ; Supercooled water ; Droplet ; Ice cloud ; Ice ; Air mass ; Satellite observation ; Infrared radiation ; ADEOS satellite ; ERS satellite ;
Source : Pascal - INIST  

High spectral resolution remote sensing for earth's weather and climate studies
1993 - 1995

Sujets :
Coordination, Cooperation, Education, Training
Participants :
Laboratoire de Météorologie Dynamique
Laboratoire de Météorologie Dynamique


Laboratoire d'Optique Atmosphèrique
Laboratoire d'Optique Atmosphèrique


FREIE UNIVERSITAET BERLIN DEUTSCHLAND
FREIE UNIVERSITAET BERLIN
Education

INSTITUT FUER WELTRAUMWISSENSCHAFTEN (WE4) - FACHBEREICH GEOWISSENSCHAFTEN Fabeckstrasse 69 14195
DEUTSCHLAND
COUNCIL FOR THE CENTRAL LABORATORY OF THE RESEARCH COUNCILS UNITED KINGDOM
COUNCIL FOR THE CENTRAL LABORATORY OF THE RESEARCH COUNCILS
Research,Other

RUTHERFORD APPLETON LABORATORIES Chilton OX11 0QX
UNITED KINGDOM
UNIVERSITE PIERRE ET MARIE CURIE - PARIS VI FRANCE
UNIVERSITE PIERRE ET MARIE CURIE - PARIS VI
Education

SERVICE D'ARONOMIE PO Box 121 Place Jussieu 4 Tour 15 75230
FRANCE

Source : Cordis  





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