The Experts below are selected from a list of 100467 Experts worldwide ranked by ideXlab platform
Robert Wood - One of the best experts on this subject based on the ideXlab platform.
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drizzle in stratiform boundary layer clouds part i vertical and Horizontal Structure
Journal of the Atmospheric Sciences, 2005Co-Authors: Robert WoodAbstract:Abstract Detailed observations of stratiform boundary layer clouds on 12 days are examined with specific reference to drizzle formation processes. The clouds differ considerably in mean thickness, liquid water path (LWP), and droplet concentration. Cloud-base precipitation rates differ by a factor of 20 between cases. The lowest precipitation rate is found in the case with the highest droplet concentration even though this case had by far the highest LWP, suggesting that drizzle can be severely suppressed in polluted clouds. The vertical and Horizontal Structure of cloud and drizzle liquid water and bulk microphysical parameters are examined in detail. In general, the highest concentration of r > 20 μm drizzle drops is found toward the top of the cloud, and the mean volume radius of the drizzle drops increases monotonically from cloud top to base. The resulting precipitation rates are largest at the cloud base but decrease markedly only in the upper third of the cloud. Below cloud, precipitation rates dec...
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Drizzle in Stratiform Boundary Layer Clouds. Part I: Vertical and Horizontal Structure
Journal of the Atmospheric Sciences, 2005Co-Authors: Robert WoodAbstract:Detailed observations of stratiform boundary layer clouds on 12 days are examined with specific reference to drizzle formation processes. The clouds differ considerably in mean thickness, liquid water path (LWP), and droplet concentration. Cloud-base precipitation rates differ by a factor of 20 between cases. The lowest precipitation rate is found in the case with the highest droplet concentration even though this case had by far the highest LWP, suggesting that drizzle can be severely suppressed in polluted clouds. The vertical and Horizontal Structure of cloud and drizzle liquid water and bulk microphysical parameters are examined in detail. In general, the highest concentration of r 20 m drizzle drops is found toward the top of the cloud, and the mean volume radius of the drizzle drops increases monotonically from cloud top to base. The resulting precipitation rates are largest at the cloud base but decrease markedly only in the upper third of the cloud. Below cloud, precipitation rates decrease markedly with distance below base due to evaporation, and are broadly consistent in most cases with the results from a simple sedimentation– evaporation model. Evidence is presented that suggests evaporating drizzle is cooling regions of the subcloud layer, which could result in dynamical feedbacks. A composite power spectrum of the Horizontal spatial series of precipitation rate is found to exhibit a power-law scaling from the smallest observable scales to close to the maximum observable scale (30 km). The exponent is considerably lower (1.1–1.2) than corresponding exponents for LWP variability obtained in other studies (1.5–2), demonstrating that there is relatively more variability of drizzle on small scales. Singular measures analysis shows that drizzle fields are much more intermittent than the cloud liquid water content fields, consistent with a drizzle production process that depends strongly upon liquid water content. The adiabaticity of the clouds, which can be modeled as a simple balance between drizzle loss and turbulent replenishment, is found to decrease if the time scale for drizzle loss is shorter than roughly 5–10 eddy turnover time scales. Finally, the data are compared with three simple scalings derived from recent observations of drizzle in subtropical stratocumulus clouds.
A. Mantzavelas - One of the best experts on this subject based on the ideXlab platform.
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A technical guide for end-users to map and describe wildland-urban interfaces in European Mediterranean wildfirerisk context
2010Co-Authors: C. Lampin-maillet, Céline Bouillon, M. Long, D. Morge, M. Jappiot, G. Herrero-coral, L. Galiana, A. MantzavelasAbstract:The paper presents the major outcomes of the produced guide. It particularly describes the method developed for mapping WUIs on large areas and at large scale in the European Mediterranean context. The method used remote sensing and spatial analysis tools. Particularly adapted to the French context, it can be easily adapted according specific contexts observed in different European countries. After specifying accurate definition of wildland-Urban Interface (WUI), a WUI typology was based on the combination of four housing configuration types and three natures of Horizontal Structure of vegetation determined through objective and quantitative criteria. Housing configuration reveals spatial organization of residential dwellings: isolated, scattered, dense clustered and very dense clustered housing. Horizontal Structure of vegetation points out the continuous vegetation, the sparse vegetation or the no existing vegetation in contact with houses. Twelve wildland-urban interface types were produced.In parallel a software tool was developed and briefly presented in the paper in order to map WUIs as automatically as possible. The production of WUI maps presents high interest for quantification of the extension of WUIs on the territory, main characteristics of WUIs, assessment and mapping of fire risk levels in WUIs. The main objective of the guide is to help end-users such as land managers, foresters and fire-fighters to locate WUIs on the ground with a view to develop specific actions for wildfires prevention according to WUI types, to create public awareness programs for inhabitants faced with wildfire risk, and to assess fire fighting difficulties due to urbanization.
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P5.2-8 Technical guide to map and describe wildland-urban interfaces (WUIs)
2009Co-Authors: C. Lampin-maillet, Céline Bouillon, M. Long, D. Morge, M. Jappiot, L. Galiana, G. Herrero, A. MantzavelasAbstract:This guide presents a method for wildland-urban interface mapping, applied to large areas, at a large scale. This method can be adapted easily to specific situations observed in different European countries. The guide is based on a combination of four housing configuration types and three types of Horizontal Structure of vegetation. Twelve wildland-urban interface types have been produced. It is particularly well adapted to the French environment, but the method has also been well adapted (and applied) to Spain and Greece. In tandem with a software tool WUImap it was developed and presented in guide-form to map WUIs automatically. Some examples of use of such WUI maps have been presented in the guide.
C. Lampin-maillet - One of the best experts on this subject based on the ideXlab platform.
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A technical guide for end-users to map and describe wildland-urban interfaces in European Mediterranean wildfirerisk context
2010Co-Authors: C. Lampin-maillet, Céline Bouillon, M. Long, D. Morge, M. Jappiot, G. Herrero-coral, L. Galiana, A. MantzavelasAbstract:The paper presents the major outcomes of the produced guide. It particularly describes the method developed for mapping WUIs on large areas and at large scale in the European Mediterranean context. The method used remote sensing and spatial analysis tools. Particularly adapted to the French context, it can be easily adapted according specific contexts observed in different European countries. After specifying accurate definition of wildland-Urban Interface (WUI), a WUI typology was based on the combination of four housing configuration types and three natures of Horizontal Structure of vegetation determined through objective and quantitative criteria. Housing configuration reveals spatial organization of residential dwellings: isolated, scattered, dense clustered and very dense clustered housing. Horizontal Structure of vegetation points out the continuous vegetation, the sparse vegetation or the no existing vegetation in contact with houses. Twelve wildland-urban interface types were produced.In parallel a software tool was developed and briefly presented in the paper in order to map WUIs as automatically as possible. The production of WUI maps presents high interest for quantification of the extension of WUIs on the territory, main characteristics of WUIs, assessment and mapping of fire risk levels in WUIs. The main objective of the guide is to help end-users such as land managers, foresters and fire-fighters to locate WUIs on the ground with a view to develop specific actions for wildfires prevention according to WUI types, to create public awareness programs for inhabitants faced with wildfire risk, and to assess fire fighting difficulties due to urbanization.
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P5.2-8 Technical guide to map and describe wildland-urban interfaces (WUIs)
2010Co-Authors: C. Lampin-maillet, Céline Bouillon, M. Long, D. Morge, M. JappiotAbstract:This poster presents a method for wildland-urban interface mapping described in the product P5.2.8, applied to large areas, at a large scale. This method can be adapted easily to specific situations observed in different European countries. The method is based on a combination of four housing configuration types and three types of Horizontal Structure of vegetation. Twelve wildland-urban interface types have been produced. It is particularly well adapted to the French environment, but the method has also been well adapted (and applied) to Spain and Greece. In tandem with a software tool WUImap it was developed and presented in guide-form to map WUIs automatically. Some examples of use of such WUI maps have been presented in the product.
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P5.2-8 Technical guide to map and describe wildland-urban interfaces (WUIs)
2009Co-Authors: C. Lampin-maillet, Céline Bouillon, M. Long, D. Morge, M. Jappiot, L. Galiana, G. Herrero, A. MantzavelasAbstract:This guide presents a method for wildland-urban interface mapping, applied to large areas, at a large scale. This method can be adapted easily to specific situations observed in different European countries. The guide is based on a combination of four housing configuration types and three types of Horizontal Structure of vegetation. Twelve wildland-urban interface types have been produced. It is particularly well adapted to the French environment, but the method has also been well adapted (and applied) to Spain and Greece. In tandem with a software tool WUImap it was developed and presented in guide-form to map WUIs automatically. Some examples of use of such WUI maps have been presented in the guide.
Jeanmichel Sarrailh - One of the best experts on this subject based on the ideXlab platform.
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characterization of the Horizontal Structure of the tropical forest canopy using object based lidar and multispectral image analysis
International Journal of Applied Earth Observation and Geoinformation, 2013Co-Authors: Stephane Dupuy, Gerard Laine, Jacques Tassin, Jeanmichel SarrailhAbstract:a b s t r a c t This article's goal is to explore the benefits of using Digital Surface Model (DSM) and Digital Terrain Model (DTM) derived from LiDAR acquisitions for characterizing the Horizontal Structure of different facies in forested areas (primary forests vs. secondary forests) within the framework of an object-oriented classification. The area under study is the island of Mayotte in the western Indian Ocean. The LiDAR data were the data originally acquired by an airborne small-footprint discrete-return LiDAR for the "Litto3D" coastline mapping project. They were used to create a Digital Elevation Model (DEM) at a spatial resolution of 1 m and a Digital Canopy Model (DCM) using median filtering. The use of two successive segmentations at different scales allowed us to adjust the segmentation parameters to the local Structure of the landscape and of the cover. Working in object-oriented mode with LiDAR allowed us to discriminate six vegetation classes based on canopy height and Horizontal heterogeneity. This heterogeneity was assessed using a texture index calculated from the height-transition co-occurrence matrix. Overall accuracy exceeds 90%. The resulting product is the first vegetation map of Mayotte which emphasizes the Structure over the composition.
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Characterization of the Horizontal Structure of the tropical forest canopy using object-based LiDAR and multispectral image analysis
International Journal of Applied Earth Observation and Geoinformation, 2013Co-Authors: Stephane Dupuy, Gerard Laine, Jacques Tassin, Jeanmichel SarrailhAbstract:a b s t r a c t This article's goal is to explore the benefits of using Digital Surface Model (DSM) and Digital Terrain Model (DTM) derived from LiDAR acquisitions for characterizing the Horizontal Structure of different facies in forested areas (primary forests vs. secondary forests) within the framework of an object-oriented classification. The area under study is the island of Mayotte in the western Indian Ocean. The LiDAR data were the data originally acquired by an airborne small-footprint discrete-return LiDAR for the "Litto3D" coastline mapping project. They were used to create a Digital Elevation Model (DEM) at a spatial resolution of 1 m and a Digital Canopy Model (DCM) using median filtering. The use of two successive segmentations at different scales allowed us to adjust the segmentation parameters to the local Structure of the landscape and of the cover. Working in object-oriented mode with LiDAR allowed us to discriminate six vegetation classes based on canopy height and Horizontal heterogeneity. This heterogeneity was assessed using a texture index calculated from the height-transition co-occurrence matrix. Overall accuracy exceeds 90%. The resulting product is the first vegetation map of Mayotte which emphasizes the Structure over the composition.
John A. Colosi - One of the best experts on this subject based on the ideXlab platform.
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Seasonal evolution of upper‐ocean Horizontal Structure and the remnant mixed layer
Journal of Geophysical Research, 2010Co-Authors: Sylvia T. Cole, Daniel L. Rudnick, John A. ColosiAbstract:[1] We discuss the seasonal evolution of upper-ocean thermohaline Structure at small Horizontal scales. The upper 350 m of a 1000 km long section in the subtropical North Pacific was observed in winter, spring, and summer with 3–14 km Horizontal resolution. Four vertical regions had distinct density and salinity Structure: the mixed layer, remnant mixed layer, high-stratification layer, and permanent thermocline. The remnant mixed layer consists of water from the winter mixed layer left over after restratification. The remnant mixed layer was most similar to the mixed layer in winter and spring, and most similar to the high-stratification layer below in summer. The high-stratification layer had elevated stratification that varied seasonally. The permanent thermocline varied little seasonally and was Horizontally and vertically uniform in comparison. In all seasons, density ratios showed that mixed-layer θ-S differences tended to compensate in density with the strongest tendency toward compensation in winter. Density ratios were temperature dominated in the remnant mixed layer consistent with salt-fingering. Salinity anomalies were largest at the surface and decayed with depth in all seasons. Spectra of isopycnal depth and θ-S anomalies along isopycnals are compared between the three seasons and four vertical layers. Isopycnal depth variance at 30–46 km wavelengths decreased from winter to spring to summer by a factor of 2–10 in stratified regions. By treating salinity anomalies as a tracer, the effective isopycnal diffusivity in the remnant mixed layer was estimated to be 1.4 m2 s−1 over 30–46 km wavelengths.
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seasonal evolution of upper ocean Horizontal Structure and the remnant mixed layer
Journal of Geophysical Research, 2010Co-Authors: Sylvia T. Cole, Daniel L. Rudnick, John A. ColosiAbstract:[1] We discuss the seasonal evolution of upper-ocean thermohaline Structure at small Horizontal scales. The upper 350 m of a 1000 km long section in the subtropical North Pacific was observed in winter, spring, and summer with 3–14 km Horizontal resolution. Four vertical regions had distinct density and salinity Structure: the mixed layer, remnant mixed layer, high-stratification layer, and permanent thermocline. The remnant mixed layer consists of water from the winter mixed layer left over after restratification. The remnant mixed layer was most similar to the mixed layer in winter and spring, and most similar to the high-stratification layer below in summer. The high-stratification layer had elevated stratification that varied seasonally. The permanent thermocline varied little seasonally and was Horizontally and vertically uniform in comparison. In all seasons, density ratios showed that mixed-layer θ-S differences tended to compensate in density with the strongest tendency toward compensation in winter. Density ratios were temperature dominated in the remnant mixed layer consistent with salt-fingering. Salinity anomalies were largest at the surface and decayed with depth in all seasons. Spectra of isopycnal depth and θ-S anomalies along isopycnals are compared between the three seasons and four vertical layers. Isopycnal depth variance at 30–46 km wavelengths decreased from winter to spring to summer by a factor of 2–10 in stratified regions. By treating salinity anomalies as a tracer, the effective isopycnal diffusivity in the remnant mixed layer was estimated to be 1.4 m2 s−1 over 30–46 km wavelengths.