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
Aerosol complexity in megacities: From size-resolved chemical composition to optical properties of the Beijing atmospheric particles
2009
Auteurs : H. Cachier, Oleg DUBOVIK, B. Guinot, B. Guinot, Marc Mallet, J. C. ROGER et Tong Yu
Masquer le résumé
Megacities need adapted tools for the accurate modeling of aerosol impacts. For this purpose a new experimental data processing has been worked out for Beijing aerosols as case study. Size-resolved aerosol particles were extensively sampled during winter and summer 2003 and subsequently fully chemically characterized. The product is an aerosol model presenting a new particle pattern (mode number, size and chemistry) without any prerequisite constrain either on the mode number or on each mode chemical composition. Six modes were found and five of them consistently appear as internally mixed particles organized around a black carbon or a dust core coated by organic and/or inorganic material. Data were checked by robust comparisons with other experimental data (particle number, sunphotometer-derived derived data). We found the presence of two accumulation modes in different internal mixing and optical calculations show that the Beijing aerosol single scattering albedo (?o # 0.90) is significantly higher than expected. Such an approach would allow realistic modeling of atmospheric particle impacts under complex situations.
Keywords :
aerosol optical properties.
Source : HAL  

Aerosol complexity in megacities: From size-resolved chemical composition to optical properties of the Beijing atmospheric particles
2009
Auteurs : Helene CACHIER, H. Cachier, Oleg DUBOVIK, Benjamin GUINOT, B. Guinot, Marc MALLET, JEAN CLAUDE ROGER, J.C. Roger et TONG YU
Masquer le résumé
[1] ] Megacities need adapted tools for the accurate modeling of aerosol impacts. For this purpose a new experimental data processing has been worked out for Beijing aerosols as case study. Size-resolved aerosol particles were extensively sampled during winter and summer 2003 and subsequently fully chemically characterized. The product is an aerosol model presenting a new particle pattern (mode number, size and chemistry) without any prerequisite constrain either on the mode number or on each mode chemical composition. Six modes were found and five of them consistently appear as internally mixed particles organized around a black carbon or a dust core coated by organic and/or inorganic material. Data were checked by robust comparisons with other experimental data (particle number, sunphotometer-derived derived data). We found the presence of two accumulation modes in different internal mixing and optical calculations show that the Beijing aerosol single scattering albedo (wo # 0.90) is significantly higher than expected. Such an approach would allow realistic modeling of atmospheric particle impacts under complex situations.
Keywords :
albedo ; Mixing ; mixing ; accumulation ; photometry ; inorganic materials ; drill cores ; dust ; Soot ; models ; Summer ; Winter ; case studies ; data processing ; Modeling ; particles ; optical properties ; chemical composition ; Complexity ; aerosols ;
Source : Pascal - INIST  

Cirrus microphysical properties and their effect on radiation : survey and integration into climate models using combined satellite observations (CIRAMOSA)
CIRAMOSA
2001 - 2003

Sujets :
Measurement Methods, Environmental Protection, Resources of the Sea, Fisheries, Meteorology, Forecasting
Participants :
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE FRANCE
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
Other,Research

UPR 1211 - LABORATOIRE DE METEOROLOGIE DYNAMIQUE Ecole Polytechnique 91128
FRANCE
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
ECOLE NORMALE SUPERIEURE FRANCE
ECOLE NORMALE SUPERIEURE
Education,Research

LABORATOIRE DE METEOROLOGIE DYNAMIQUE Rue Lhomond 24 75231
FRANCE
UNIVERSITY OF SCIENCE AND TECHNOLOGY OF LILLE FRANCE
UNIVERSITY OF SCIENCE AND TECHNOLOGY OF LILLE
Education

UMR 8518 - LABORATOIRE D'OPTIQUE ATMOSPHÉRIQUE Bètiment P5 59655
FRANCE
SECRETARY OF STATE FOR DEFENCE - MINISTRY OF DEFENCE UNITED KINGDOM
SECRETARY OF STATE FOR DEFENCE - MINISTRY OF DEFENCE
Research

METEOROLOGICAL OFFICE HADLEY CENTRE FOR CLIMATE PREDICTION AND RESEARCH Fitzroy Road, Metz Office EX1 3PB
UNITED KINGDOM
Laboratoire de Météorologie Dynamique
Laboratoire de Météorologie Dynamique


Laboratoire d'Optique Atmosphèrique
Laboratoire d'Optique Atmosphèrique


Hide objectives
The radiation effect due to changes of microphysical properties within cirrus clouds can be very important. We will provide a long-term survey of these properties, together with cirrus macrophysical properties, and then establish a compilation of correlations between them and the state of the atmosphere. This information is essential for the understanding of changes in clouds expected by a global climate change. Satellite instruments measuring radiation with a good spectral resolution as well as multi-angular measurements of polarized reflectance used with newly developed retrieval algorithms are now capable to give this information over the whole globe. Extensive care will be taken of the validation of the retrieved cirrus properties by intercomparison with data sets from regional measurement campaigns. Models for climate prediction can profit from the outcome of this proposal by using the most appropriate correlations in their radiation codes.

Source : Cordis  

Aerosol extinction profiles at 525 nm and 1020 nm derived from ACE imager data: comparisons with GOMOS, SAGE II, SAGE III, POAM III, and OSIRIS
2008
Auteurs : P. F. Bernath, C. D. Boone, A. Bourassa, Colette Brogniez, D. Degenstein, J. Dodion, M. Fromm, D. Fussen, K. L. Gilbert, D. N. Turnbull, C. Tétard, F. Vanhellemont et K. A. Walker
Masquer le résumé
The Canadian ACE (Atmospheric Chemistry Experiment) mission is dedicated to the retrieval of a large number of atmospheric trace gas species using the solar occultation technique in the infrared and UV/visible spectral domain. However, two additional solar disk imagers (at 525 nm and 1020 nm) were added for a number of reasons, including the retrieval of aerosol and cloud products. In this paper, we present first comparison results for these imager aerosol/cloud optical extinction coefficient profiles, with the ones derived from measurements performed by 3 solar occultation instruments (SAGE II, SAGE III, POAM III), one stellar occultation instrument (GOMOS) and one limb sounder (OSIRIS). The results indicate that the ACE imager profiles are of good quality in the upper troposphere/lower stratosphere, although the aerosol extinction for the visible channel at 525 nm contains a significant negative bias at higher altitudes, while the relative differences indicate that ACE profiles are almost always too high at 1020 nm. Both problems are probably related to ACE imager instrumental issues.
Keywords :
Source : HAL  

Characteristics of the UV radiation field in the Alps
1998 - 2000

Sujets :
Meteorology, Forecasting, Measurement Methods, Environmental Protection
Participants :
LEOPOLD-FRANZENS-UNIVERSITAET INNSBRUCK ÖSTERREICH
LEOPOLD-FRANZENS-UNIVERSITAET INNSBRUCK
Education

INSTITUTE OF MEDICAL PHYSICS 44,Müllerstrasse 44 6020
ÖSTERREICH
FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V. DEUTSCHLAND
FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V.
Research

INSTITUT FUER ATMOSPHAERISCHE UMWELTFORSCHUNG EV Kreuzeckbahnstrasse 19 82467
DEUTSCHLAND
UNIVERSITAET FUER BODENKULTUR WIEN ÖSTERREICH
UNIVERSITAET FUER BODENKULTUR WIEN
Education,Other

INSTITUT FÜR METEOROLOGIE UND PHYSIK 18,Turkenschanzstrasse 18 1180
ÖSTERREICH
UNIVERSITY OF SCIENCE AND TECHNOLOGY OF LILLE FRANCE
UNIVERSITY OF SCIENCE AND TECHNOLOGY OF LILLE
Education

UMR 8518 - LABORATOIRE D'OPTIQUE ATMOSPHÉRIQUE Bètiment P5 59655
FRANCE
UNIVERSITE JOSEPH FOURIER - GRENOBLE 1 FRANCE
UNIVERSITE JOSEPH FOURIER - GRENOBLE 1
Education

EQUIPE INETERACTIONS RAYONNEMENT SOLAI RE ATMOSPHÈRE Quai Claude Bernard 17 38000
FRANCE
Physikalisch-Meteorologisches Observatorium Davos SCHWEIZ/SUISSE/SVIZZERA
Physikalisch-Meteorologisches Observatorium Davos
Research

Weltstrahlungszentrum 33,Dorfstraße 7260
SCHWEIZ/SUISSE/SVIZZERA
Laboratoire d'Optique Atmosphèrique
Laboratoire d'Optique Atmosphèrique



Source : Cordis  

Application of randomly oriented spheroids for retrieval of dust particle parameters from multiwavelength lidar measurements
2010
Auteurs : Oleg DUBOVIK, P. Di Girolamo, A. Kolgotin, T. LAPYONOK, Michael I. MISHCHENKOL, D. SUMMA, Didier TANRE, I. VESELOVSKII et David N. WHITEMAN
Masquer le résumé
[1] Multiwavelength (MW) Raman lidars have demonstrated their potential to profile particle parameters; however, until now, the physical models used in retrieval algorithms for processing MW lidar data have been predominantly based on the Mie theory. This approach is applicable to the modeling of light scattering by spherically symmetric particles only and does not adequately reproduce the scattering by generally nonspherical desert dust particles. Here we present an algorithm based on a model of randomly oriented spheroids for the inversion of multiwavelength lidar data. The aerosols are modeled as a mixture of two aerosol components: one composed only of spherical and the second composed of nonspherical particles. The nonspherical component is an ensemble of randomly oriented spheroids with size-independent shape distribution. This approach has been integrated into an algorithm retrieving aerosol properties from the observations with a Raman lidar based on a tripled Nd:YAG laser. Such a lidar provides three backscattering coefficients, two extinction coefficients, and the particle depolarization ratio at a single or multiple wavelengths. Simulations were performed for a bimodal particle size distribution typical of desert dust particles. The uncertainty of the retrieved particle surface, volume concentration, and effective radius for 10% measurement errors is estimated to be below 30%. We show that if the effect of particle nonsphericity is not accounted for, the errors in the retrieved aerosol parameters increase notably. The algorithm was tested with experimental data from a Saharan dust outbreak episode, measured with the BASIL multiwavelength Raman lidar in August 2007. The vertical profiles of particle parameters as well as the particle size distributions at different heights were retrieved. It was shown that the algorithm developed provided substantially reasonable results consistent with the available independent information about the observed aerosol event.
Keywords :
Africa ; Sahara ; dust storms ; Measurement error ; Effective radius ; concentration ; uncertainties ; Particle size distribution ; simulation ; wavelength ; Depolarization ratio ; Extinction index ; backscattering ; laser methods ; aerosols ; inverse problem ; deserts ; Spherical symmetry ; Light scattering ; Modeling ; theory ; Retrieval algorithm ; physical models ; Lidar ; particles ; dust ; Spheroid ;
Source : Pascal - INIST  

Aerosol variability over East Asia as seen by POLDER space-borne sensors
2010
Auteurs : CHIAPELLO, H Chen, F. DUCOS, Z. LI, Goloub PHILLIPPE et X. SU
Masquer le résumé
[1] This paper is devoted to analysis of aerosol distribution and variability over East Asia based on PARASOL/POLDER-3 aerosol products over land. We first compared POLDER-3 Aerosol Optical Depth (AOD) with fine mode AOD (particles radius ≤ 0.30 μm) computed from AERONET (Aerosol Robotic Network) inversions over 14 sites. The rather good correlation (R ≈ 0.92) observed over land demonstrates the remarkable sensitivity of POLDER-3 retrievals to the smaller fraction of fine particles, mostly originating from anthropogenic sources. We analyzed the characteristics and seasonal variation of aerosol distribution over East Asia by considering 4 years of POLDER-3 Level 2 data (March 2005 to February 2009). Our study shows that the spatial distribution of fine-mode aerosols over East Asia, as retrieved from POLDER-3, is highly associated with human activities. Our work also evidenced a strong variability of seasonal fine-mode AOD patterns with geographical locations. Finally, the interannual variation during 2003-2009 periods of summer fine-mode AOD over North China, in particular the Beijing City region, was analyzed for the contribution to evaluating the regional impact of emission reduction enforced in Beijing during the 2008 Olympic Summer Games. We found that the summer average of fine-mode AOD exhibited relatively higher values in 2003, 2007, and 2008. The interannual variation patterns of monthly averaged AOD (June to August) shows that June generally exhibits the strongest variation and varies similarly to July, but differs from August. As a reference point, measured total AOD and fine-mode AOD computed from AERONET inversions in summer are also discussed for the Beijing City region.
Keywords :
Asia ; Far East ; China ; Europe ; Southern Europe ; Italy ; Beijing China ; Northern China ; Marches Italy ; exhibits ; Pollution abatement ; Regional scope ; urban areas ; Summer ; Interannual variation ; Human activity ; human activity ; Spatial distribution ; spatial distribution ; seasonal variations ; Anthropogenic factor ; Fine particle ; sensitivity analysis ; correlation ; inverse problem ; networks ; Particle radii ; fine-grained materials ; Optical thickness ; polders ; variability ; aerosols ;
Source : Pascal - INIST  





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