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dc.contributor.advisorO'Neill, Norman T.
dc.contributor.authorNassif Moussa Daou, Davidfr
dc.date.accessioned2015-02-05T15:09:23Z
dc.date.available2015-02-05T15:09:23Z
dc.date.created2012fr
dc.date.issued2015-02-05
dc.identifier.urihttp://hdl.handle.net/11143/6058
dc.description.abstractAerosols are small, micrometer-sized particles, whose optical effects coupled with their impact on cloud properties is a source of large uncertainty in climate models. While their radiative forcing impact is largely of a cooling nature, there can be significant variations in the degree of their impact, depending on the size and the nature of the aerosols. The radiative and optical impact of aerosols are, first and foremost, dependent on their concentration or number density (an extensive parameter) and secondly on the size and nature of the aerosols (intensive, per particle, parameters). We employed passive (sunphotmetry) and active (backscatter lidar) measurements to retrieve extensive optical signals (aerosol optical depth or AOD and backscatter coefficient respectively) and semi-intensive optical signals (fine and coarse mode OD and fine and coarse mode backscatter coefficient respectively) and compared the optical coherency of these retrievals over a variety of aerosol and thin cloud events (pollution, dust, volcanic, smoke, thin cloud dominated). The retrievals were performed using an existing spectral deconvolution method applied to the sunphotometry data (SDA) and a new retrieval technique for the lidar based on a colour ratio thresholding technique. The validation of the lidar retrieval was accomplished by comparing the vertical integrations of the fine mode, coarse mode and total backscatter coefficients of the lidar with their sunphotometry analogues where lidar ratios (the intensive parameter required to transform backscatter coefficients into extinction coefficients) were (a) computed independently using the SDA retrievals for fine mode aerosols or prescribed for coarse mode aerosols and clouds or (b) computed by forcing the computed (fine, coarse and total) lidar ODs to be equal to their analog sunphotometry ODs. Comparisons between cases (a) and (b) as well as the semi-qualitative verification of the derived fine and coarse mode vertical profiles with the expected backscatter coefficient behavior of fine and coarse mode aerosols yielded satisfactory agreement (notably that the fine, coarse and total OD errors were <~ sunphotometry instrument errors). Comparisons between cases (a) and (b) also showed a degree of optical coherency between the fine mode lidar ratios.fr
dc.language.isofrefr
dc.publisherUniversité de Sherbrookefr
dc.rights© David Nassif Moussa Daoufr
dc.subjectRemote sensingfr
dc.subjectAtmospheric Physicsfr
dc.subjectAerosolsfr
dc.subjectFine and coarse particlesfr
dc.subjectLidarfr
dc.subjectSunphotometerfr
dc.subjectInversion techniquefr
dc.subjectAngstrom exponentfr
dc.subjectLidar ratiofr
dc.subjectBackscatter coefficientfr
dc.subjectExtinction coefficientfr
dc.subjectSpectral Deconvolution Algorithmfr
dc.subjectAerosol optical depthfr
dc.subjectTélédétectionfr
dc.subjectPhysique de l’atmosphèrefr
dc.subjectAérosolsfr
dc.subjectParticules fines et grossesfr
dc.subjectPhotomètrefr
dc.subjectMéthodes d'inversionfr
dc.subjectCoefficient d'Angstromfr
dc.subjectCoefficient de rétrodiffusionfr
dc.subjectCoefficient d'extinctionfr
dc.subjectSDAfr
dc.subjectÉpaisseur optiquefr
dc.titleCaractérisation des aérosols par inversion des données combinées des photomètres et lidars au sol.fr
dc.typeThèsefr
tme.degree.disciplineTélédétectionfr
tme.degree.grantorFaculté des lettres et sciences humainesfr
tme.degree.levelDoctoratfr
tme.degree.namePh.D.fr


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