CLIMATE VARIABILITY STUDY IN NORTHERN HIGH LATITUDES DERIVED FROM MICROWAVES REMOTE SENSING OBSERVATIONS.

• Main Author: Mialon, Arnaud
• Other Authors: Centre d'Applications et de Recherches en TELédétection Sherbrooke (CARTEL), Département de géomatique appliquée Sherbrooke (UdeS), Université de Sherbrooke (UdeS)-Université de Sherbrooke (UdeS), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Joseph-Fourier - Grenoble I, Université de Sherbrooke, FILY Michel([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2005
• Subjects: remote sensing; passive microwaves; SSM/I satellite sensor; northern high latitudes; surface temperature; inundated areas; permafrost; télédétection; micro-ondes passives; capteur satellite SSM/I; hautes latitudes nord; température de surface; zones inondées; pergélisol; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Alaska
• Online Access: https://theses.hal.science/tel-00011322; https://theses.hal.science/tel-00011322/document; https://theses.hal.science/tel-00011322/file/these.pdf

Observing sub-polar ecosystems is important as they are suspected to change significantly in response to the expected increase in temperature for the next decades. To bypass the lack of meteorological stations in the Northern High Latitudes, remote sensing is an interesting alternative tool, covering almost the entire area. This project deals with the development of a method to derive surface parameters (>50°N) from satellite data. For this study, brightness temperature data acquired by the SSM/I (Special Sensor Microwave Imager) in the microwave spectrum are used because they are independent of solar radiation and weakly influenced by the atmosphere. Methods used are based on brightness temperatures measured at 19 and 37 GHz, which allow to derive three geophysical parameters related to climate variability : daily maps of snowcover between 1988 and 2002 a water surface extent (open water, small lakes, reservoirs, wetlands associated with low vegetation) a temperature characterizing the surface and the air above the ground. A method to normalize the temperature is presented to overcome the variation of the time of measurement. It leads to hourly series of temperature, This allows to study climate indicators such as the annual sum of positive degree days.Trends confirm observed climate evolution : increase of surface temperature (+0.8 +/- 0.4 °C for Canada/Alaska between 1992 and 2002), decrease in snow extent cover. These original databases could also be useful for validation of regional climate model. Le suivi des milieux sub-polaires est important, tant ils devraient évoluer face à l'augmentation des températures attendue dans ces régions au cours des prochaines décennies. Pour pallier au manque de stations météorologiques affectant les hautes latitudes, la télédétection spatiale est une alternative intéressante, offrant une couverture spatiale quasi-globale. Ce projet s'inscrit dans le développement de méthodes pour extraire de ces données des informations relatives à la surface des latitudes nord ...