报告人：Dr. Darren Ghent, PI on the ESA LST CCI Project. Department of Physics and Astronomy, University of Leicester, UK
报告内容简介：Land surface temperature (LST) is the radiative skin temperature of the land andis derived from solar radiation.It is influenced by land/atmosphere boundary conditions and exerts control over the partitioning of energy into latent and sensible heat fluxes,and heat flux into the ground. LST is distinct from air temperature with substantial differences possible between concurrent measurements of the same scene. It displays a strong diurnal cycle and is sensitive to surface characteristics such as vegetation cover, and soil moisture; whereby it can exhibit substantial non-uniformity over just a few metres.
Instruments onboard Earth Observation satellites determine LST from top-of-atmosphere (TOA) radiances at microwave and thermal infrared wavelengths by applying a radiative transfer equation.This combines the upwelling radiance emitted by the ground, the upwelling radiance emitted by the atmosphere, and the down-welling radiance emitted by the atmosphere and reflected by the ground.
LST retrieval accuracy can be challenging as a result of emissivity variability andatmospheric effects. Surface emissivities can be highly variable owing to the heterogeneity of the land; a problem which is amplified in regions of high topographic variance or for larger viewing angles.Atmospheric effectscaused by the presence of aerosols and by water vapour absorption can give a bias to the underlying LST.If not accounted for, atmospheric effects and emissivity variability can result in retrieval errors of several degrees.
报告人简介：Dr. Darren Ghenthas over 10 years of experience working with land surface temperature data, from its retrieval to its exploitation. Indeed, his research interests include the interactions between the land-surface and the atmosphere in terms of the surface energy balance, carbon and water cycles. He is particularly concerned with validating land-surface temperature, both the products from Earth Observation and the simulations of land-surface models; developing improved land surface temperature algorithms, in particular being responsible for the algorithms for ESA instruments - AATSR and SLSTR; exploitation of land surface temperature in scientific and commercial applications; modelling the biogeochemical processes of terrestrial ecosystems; and climate feedbacks on various spatial and temporal scales. To improve the modelling of these processes, he has been involved in constraining land-surface.