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Jan Pisek Jing M. Chen Roselyne Lacaze Oliver Sonnentag Krista Alikas 《ISPRS Journal of Photogrammetry and Remote Sensing》2010,65(4):341-346
The clumping index measures the spatial aggregation (clumped, random and regular) of foliage elements. The global mapping of the clumping index with a limited eight-month multi-angular POLDER 1 dataset is expanded by integrating new, complete year-round observations from POLDER 3. We show that terrain-induced shadows can enhance bi-directional reflectance distribution function variation and negatively bias the clumping index (i.e. indicating more vegetation clumping) in rugged terrain. Using a global high-resolution digital elevation model, a topographic compensation function is devised to correct for this terrain effect. The clumping index reductions can reach up to 30% from the topographically non-compensated values, depending on terrain complexity and land cover type. The new global clumping index map is compared with an assembled set of field measurements from 32 different sites, covering four continents and diverse biomes. 相似文献
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J. Lacaze 《Boundary-Layer Meteorology》1978,15(4):525-526
Sans résumé
Comments on the characteristics of turbulent velocity components in the surface layer under convective conditions相似文献
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J.C. Lacaze 《Marine pollution bulletin》1974,5(10):153-156
Ecotoxicological investigations are generally undertaken in the laboratory on some constituents of ecosystems. The complementary synthetic aspect, comprising the analysis of the overall effect of a pollutant on an ecosystem, also falls within the framework of the science of pollution. The present study deals with the effects of a crude Kuwait oil on the primary production of experimental ecosystems 相似文献
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Petroleum products discharged at the water surface are rapidly modified under the effect of physico-chemical and biological transformations, themselves closely dependent on ecological factors. The rôle of some of these, such as illumination, may be particularly significant. This report deals with the effect of this parameter on the phytotoxicity of Kuwait crude oil on the primary production of a microalga: (Phaeodactylum tricornutum) and marine plankton communities.The result of these investigations indicates that the toxicity of extracts made from a crude oil is about two to three times greater when the latter is previously subjected to illumination of sufficient intensity and duration. The incorporation of a chemical dispersant (Corexit 8666) magnifies this phenomenon. In the case of a weathered crude oil mixed in equal parts with the dispersant, illumination raises the toxicity of the extracts by a factor of about 30. 相似文献