The influence of winter time boreal forest tree transmissivity on tree emission and passive microwave snow observations

dc.contributor.authorLi, Qinghuan
dc.date.accessioned2019-05-17T17:27:29Z
dc.date.available2019-05-17T17:27:29Z
dc.date.issued2019-05-17
dc.date.submitted2019-05-15
dc.description.abstractForest cover significantly attenuates natural upwelling ground microwave emission from seasonal terrestrial snow. This presents a major challenge for the accurate retrieval of snow from airborne or spaceborne passive microwave (PM) observations. Forest transmissivity is a key parameter describing tree emission because not only does it influence the proportion of sub-canopy upwelling microwave emission penetrating through the forest canopy, it also controls the forest thermal emission. Hence, it is a very important parameter for correcting the influence of forests on spaceborne or airborne observations of the Earth’s land surface. Under sub-zero temperatures, vegetation water content can be frozen influencing the microwave transmissivity of trees. Yet this phenomenon has not been verified through experimentation leaving significant uncertainty in tree emission modelling and spaceborne microwave observations. Therefore, a season-long experiment was designed to study this phenomenon. Ground-based radiometer observations of tree emission, spaceborne observations of forest emission, and model simulations of canopy emission were conducted during this experiment. Based on this experiment, the influence of physical temperature on tree transmissivity was verified, and a model developed to quantitatively describe this temperature-transmissivity relationship. An evaluation of this temperature-transmissivity relationship was conducted showing that both ground-based and spaceborne observations of tree emission are significantly influenced by this phenomenon. Furthermore, passive microwave spaceborne snow retrievals in forested regions are influenced by this phenomenon. Finally, an approach to reduce the influence of the temperature-transmissivity relationship on passive microwave spaceborne snow retrievals is demonstrated.en
dc.identifier.urihttp://hdl.handle.net/10012/14641
dc.language.isoenen
dc.pendingfalse
dc.publisherUniversity of Waterlooen
dc.subjectforesten
dc.subjectsnowen
dc.subjecttransmissivityen
dc.subjectpassive microwaveen
dc.subjecttemperatureen
dc.titleThe influence of winter time boreal forest tree transmissivity on tree emission and passive microwave snow observationsen
dc.typeDoctoral Thesisen
uws-etd.degreeDoctor of Philosophyen
uws-etd.degree.departmentGeography and Environmental Managementen
uws-etd.degree.disciplineGeographyen
uws-etd.degree.grantorUniversity of Waterlooen
uws.contributor.advisorKelly, Richard
uws.contributor.affiliation1Faculty of Environmenten
uws.peerReviewStatusUnrevieweden
uws.published.cityWaterlooen
uws.published.countryCanadaen
uws.published.provinceOntarioen
uws.scholarLevelGraduateen
uws.typeOfResourceTexten

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