Papers by Jean-pierre Frangi
Characterizing Nonrigid Aggregated Soil–Water Medium Using its Shrinkage Curve
Soil Science Society of America Journal, 2004
... eled; and 3. Those considering the entire SC but making teractions act at these small scales ... more ... eled; and 3. Those considering the entire SC but making teractions act at these small scales and are the agents of assumptions on the shape of the phases, as is the case of the models of Tariq and Durnford (1993) and soil physical properties that emerge at the macroscopic ...
Revue des sciences de l'eau, 2000
Experimental Studies of the Turbulence Structure Parameters of the Convective Boundary Layer
Journal of Climate and Applied Meteorology, 1983
We present a collection of experimental data concerning turbulent characteristics of the convecti... more We present a collection of experimental data concerning turbulent characteristics of the convective boundary layer. These data were obtained by means of instrumented aircraft during numerous experiments carried out above five flight areas from 1973 to 1978. Only dry convective conditions with weak dynamic instability are contained in this report. The computed quantities are vertical turbulent fluxes of sensible and
Journal of Applied Meteorology
Atmospheric 85 Kr concentrations have been continuously monitored since 1995 at the Meteorologica... more Atmospheric 85 Kr concentrations have been continuously monitored since 1995 at the Meteorological Research Institute (MRI) in Tsukuba, Japan. They have also been observed once a year at several stations over the Japanese islands since 1995. The annual growth rate of the background atmospheric 85 Kr concentrations in Tsukuba was 0.03 Bq·m -3 ·yr -1 during 1996-2001. The atmospheric 85 Kr concentrations at several stations over Japan were within the range of the annual variations in Tsukuba. However, higher and lower 85 Kr concentrations in early winter, compared with those in Tsukuba (36.
Wind erosion and loss of soil nutrients in semi-arid Spain (WELSONS)
Spatial Variability of Co On The Scale of The Street According To Street Morphology, Car Traffic and Local Climate In Paris
The purpose of this study is to observe CO distribution on street level according to variations o... more The purpose of this study is to observe CO distribution on street level according to variations of car traffic, weather situation and street morphology. The experimentation use an electronical CO sensor connected to a data logger. Two kinds of observations are carried out : - measurements along an itinerary from the n´ butte de Montmartre z to the n´ Seine
Tomographe ultrasonore, systeme et procede de mesure tomographique ultrasonore au moyen d'un tel tomographe
Dispositif de radiométrie pour déterminer les caractéristiques physico-chimiques d'un échantillon en tenant compte de l'épaisseur
Dispositif et procédé de radiométrie pour déterminer les caractéristiques physico-chimiques d'un échantillon
DYNAMIQUE DE LA COUCHE LIMITE DE SURFACE SEMI-ARIDE APPROCHE DES CARACTERISTIQUES TURBULENTES PAR ANEMOMETRIE A COUPELLES ET EFFETS DES TRAITEMENTS DE SURFACE DU SOL
Ce livre traite des possibilités qu''offrent les anémomètres à coupelles (robustes et rap... more Ce livre traite des possibilités qu''offrent les anémomètres à coupelles (robustes et rapides) dans l''appréhension des phénomènes liés à la turbulence du vent et de l''influence des traitements de surface du sol (labour) sur ces phénomènes. La variance du vent horizontal, les échelles intégrales d''Euler, le spectre basse fréquence de la turbulence, le taux de dissipation de l''énergie cinétique turbulente (ECT) et le facteur de pointe de la vitesse du vent sont affectés par l''état de surface du sol (rugosité). Les données de base sont issues de la campagne internationale WELSONS (Wind Erosion and Loss of Soil Nutrients in Semi-Arid Spain) et des expériences complémentaires effectuées en laboratoire et en milieu urbain, avec un anémomètre sonique de référence. Au voisinage du sol, la variance du vent horizontal croît de façon logarithmique avec la hauteur, en relation avec la vitesse de frottement et la longueur de rugosité: ceci a p...
Constraining a physically based SVAT model with surface water content and thermal infrared brightness temperature measurements using a multiojective approach
The aim of this paper is to assess the influence of aerodynamic resistance modelisations commonly... more The aim of this paper is to assess the influence of aerodynamic resistance modelisations commonly used in two-layer SVAT models, on the surface fluxes and temperatures simulation.
Water Resources Research, 2005
Received 30 September 2004; accepted 4 November 2004; published 20 January 2005. [1] This article... more Received 30 September 2004; accepted 4 November 2004; published 20 January 2005. [1] This article reports on a multiobjective approach which is carried out on the physically based Soil-Vegetation-Atmosphere Transfer (SVAT) model. This approach is designed for (1) ...
Isotope characteristics of meteoric water and groundwater in the Sahelo-Sudanese zone
Journal of Geophysical Research, 1992
The stable isotopic concentration (18O and 2H) of water in phreatic aquifers in the Sahelo-Sudane... more The stable isotopic concentration (18O and 2H) of water in phreatic aquifers in the Sahelo-Sudanese zone of Africa is representative of the original mean rainfall contributing to groundwater recharge. The isotopic decrease of 18O in the rainwater and groundwater (-0.084% 100 km-1) showed an east-west gradient. This suggests a supply of water vapor transported by the zonal flows East African
Etude de la couche limite de surface sahelienne — Experience Yantala
Boundary-Layer Meteorology, 1988
Abstract This paper presents data concerning the energy budget in the surface layer in the Sahel... more Abstract This paper presents data concerning the energy budget in the surface layer in the Sahel region (a semi-desert area). The results are drawn from a measurement campaign made in the Niamey region in the Niger, in April–May 1984 (the Yantala Campaign). The sensible heat flux is computed with the profile method, the ground heat flux is deduced from measurement of
Boundary-Layer Meteorology, 1988
The measurements obtained during the ECLATS experiment were used in order to determine the surfac... more The measurements obtained during the ECLATS experiment were used in order to determine the surface energy budget of the Sahel region (Niamey, Niger). This expedition was carried out from November 15 to December 10, 1980, during the dry period. Some data were collected by an instrumented aircraft, from which the turbulent fluxes were obtained in the boundary layer around midday; data were also collected at a surface station in order to estimate the surface energy budget continuously by the profile method. The aircraft measurements show the homogeneity of the vertical fluxes over large areas, allowing generalization to the bushy steppe of the Sahel region. The mean diurnal cycle of the energy budget is characterized by high values of ground heat flux and weak values of latent heat flux (deduced from the balance of the energy budget). This cycle is compared with that of the Koorin expedition, performed in similar conditions (tropical savanna in the dry period). We compare the three midday budgets: during Koorin; during ECLATS, at the ground station, and with the aircraft. The important differences that appear in the net radiative flux are explained by the difference in surface albedo.
Agronomie, 2002
The aim of this paper is to assess the influence of aerodynamic resistance modelisations commonly... more The aim of this paper is to assess the influence of aerodynamic resistance modelisations commonly used in two-layer SVAT models, on the surface fluxes and temperatures simulation. For this purpose, a large review of the existing schemes has been conducted and 6 parameterisations have been retained.
Great progress has been made within the last decade in the modeling of radiation transfer in vege... more Great progress has been made within the last decade in the modeling of radiation transfer in vegetation canopies and recently in plant leaves. Radiosity or ray tracing models have opened new prospects in the application of remote sensing to agriculture and ecology. At the leaf scale, it is now possible to track a single photon from cell to cell and to derive the optical properties of the entire blade by following the paths of millions of photons. As a detailed description of the three-dimensional leaf internal structure is required, the first part of this paper reviews the methods to obtain that kind of information. The second part is a sensitivity analysis of the Raytran model: the absorption profiles of two leaves with different internal structures are calculated and commented.
The capability for in situ measurements of leaf biochemistry is very useful for applications in a... more The capability for in situ measurements of leaf biochemistry is very useful for applications in agriculture, forestry or ecology. A portable field radiometer, RAMIS (RAdiomètre portatif de Mesure In Situ) has been developed by the University of Paris 7 − Denis Diderot for this purpose. Unlike the SPAD-502 (Minolta) and CCM-200 (Opti-Sciences) devices which were only designed to determine total chlorophyll concentration, RAMIS should additionally estimate the leaf equivalent water thickness and the leaf mass per area (or specific leaf area) by measuring leaf transmittance at five wavelengths in the VIS-NIR-MIR and inversion of the PROSPECT leaf optical properties model.
A prototype instrument called RAMIS has been designed to non-destructively measure the biochemica... more A prototype instrument called RAMIS has been designed to non-destructively measure the biochemical properties of plant leaves such as water, dry matter, and total chlorophyll content. The spectral distribution of light transmitted through the leaf is closely related to the concentration of these constituents. In consequence, their retrieval from in situ optical measurements is possible by selecting the appropriate wavelengths. In RAMIS, the adaxial face of the leaf is alternately illuminated by five light-emitting diodes
Résumé Quatre modèles de transfert radiatif sont comparés en modes direct et inverse. Ces modèles... more Résumé Quatre modèles de transfert radiatif sont comparés en modes direct et inverse. Ces modèles sont des couplages du modèle de propriétés optiques des feuilles PROSPECT et des modèles de réflectance des couverts végétaux SAIL, IAPI, KUUSK et NADI. Les valeurs de réflectance spectrale et directionnelle simulées montrent une bonne cohérence entre eux. Afin d'évaluer leur capacité à estimer les caractéristiques de la végétation, des inversions ont d'abord été réalisées sur des spectres synthétiques (10 longueurs d'onde dans le visible et le proche infrarouge). Au vu de résultats satisfaisants, une campagne de mesures organisée en 1997 aux Etats Unis a permis de tester la performance de ces modèles en situation réelle. Cette expérience représente un imposant jeu de données constitué de 200 spectres de réflectance acquis sur des champs de maïs (Zea mays L.) et de soja (Glycine max), ainsi que des vérités terrain correspondante (concentration en chlorophylles a+b et indice ...
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Papers by Jean-pierre Frangi