Application of the Hess-Brezowsky classification to the identification of weather patterns causing heavy winter rainfall in Brittany (France)

An accurate knowledge of the weather patterns causing winter rainfall over the Scorff watershed in western Brittany (W. France) was developed prior to studies of the impact of the climate factor on land use management, and of the hydrological reponses to rain-producing weather patterns. These two studies are carried out in the context of the climate change. The identification of rainy air-circulation types was realized using the objective computational version of the 29-type Hess and Brezowsky Grosswetterlagen system of classifying European synoptic regimes, for the cold season (November-March) of the 1958–2005 period at the reference weather station of Lorient, and 13 other stations located in western and southern Brittany, including a more detailed study for the wet 2000–2001 cold season for three reference stations of the Scorff watershed (Lorient, Plouay and Plouray). The precipitation proportion (including the days with rainfall ≥20 mm) was calculated by major air-circulation type (GWT: see Appendix A) and by individual air-circulation subtype (GWL: see Appendix A) for the studied time-period. The most frequently occurrence of rainy days associated with westerly and southerly GWL confirmed well-known observations in western Europe and so justify the use of the Hess-Brezowsky classification in other areas outside Central Europe. The southern or south-western exposure of the watershed with a hilly inland area enhanced the heavy rainfall generated by the SW and S circulation types, and increased the difference between the rainfall amounts of coastal and inland stations during the wettest days

The Evolution of the EH4 Chondrite Indarch at High Pressure and Temperature: The First Experimental Results

Chondrite groups are characterized by variations in bulk composition and oxidation state, illustrating in part heterogeneity in the early solar nebula. Planetary accretion could be explained by at least two different scenarios: the homogeneous [1] and heterogeneous accretion models [2, 3]. In particular, for the formation of the Earth, some studies (e.g. [2, 3]) assume that one component is highly reduced material comparable to enstatite chondrites, devoid of volatile elements but containing all other elements in C1 abundance ratios. To derive constraints on the understanding of early differentiation processes, studies of the silicate phase relations and their interactions with metal, at relevant P-T-fO2, are required. Melting relations and equilibrium partitioning behaviour have been studied on peridotitic and chondritic starting compositions at pressures and temperatures corresponding to the transition zone and lower mantle [4, 5, 6]. However, enstatite chondrites, which are highly reduced primitive meteorites, have not yet been studied experimentally under such conditions. Thus, multianvil experiments have been performed at 20-25 GPa and 2000-2400 C on the EH4 chondrite Indarch

Variação temporal da biomassa do café arábica arborizado e a pleno sol, através de índices de vegetação.

Abstract. In recent years, several works have been accomplished in order to analyze the spectral response of coffee crop fields cultivated in full sun. However, the number of papers related to the monitoring of shaded coffee systems is reduced although this kind of cultivation is very important from the perspective of climate change and agriculture. In addition, the biomass of coffee systems can store carbon, which is a mitigation action. In this context, this paper presents the assessment of the meteorological variation joined with the biomass increase in three different coffee plantation systems: full sun, shaded coffee associated with legumes (SAF), and shaded coffee with Macadamia trees. We used Landsat-5 images from 2004 to 2010, and the NDVI and SAVI indexes. LAI index measured in the test area during all 2009 year. The results showed that the shaded coffee systems presented the NDVI and SAVI indexes with higher values than those found with the system of planting in full sun what corroborates the idea of greater amount of biomass in this type of planting. All indexes present the seasonal rain variation. One month after a large period of drought the indexes NDVI, SAVI and LAI decrease. The NDVI and SAVI indexes presented high correlation with the measured LAI. The shaded coffee system and the full sun coffee reached high vegetation indexes what indicate a high concentration of biomass. This factor should be considered in the decision making process since is important to take advantage of cultivation systems acting as carbon sinks.SBSR 2011

Nickel and helium evidence for melt above the core–mantle boundary

High ^(3)He/^(4)He ratios in some basalts have generally been interpreted as originating in an incompletely degassed lower-mantle source. This helium source may have been isolated at the core–mantle boundary region since Earth’s accretion. Alternatively, it may have taken part in whole-mantle convection and crust production over the age of the Earth; if so, it is now either a primitive refugium at the core–mantle boundary or is distributed throughout the lower mantle. Here we constrain the problem using lavas from Baffin Island, West Greenland, the Ontong Java Plateau, Isla Gorgona and Fernandina (Galapagos). Olivine phenocryst compositions show that these lavas originated from a peridotite source that was about 20 per cent higher in nickel content than in the modern mid-ocean-ridge basalt source. Where data are available, these lavas also have high ^(3)He/^(4)He. We propose that a less-degassed nickel-rich source formed by core–mantle interaction during the crystallization of a melt-rich layer or basal magma ocean, and that this source continues to be sampled by mantle plumes. The spatial distribution of this source may be constrained by nickel partitioning experiments at the pressures of the core–mantle boundary

Monitoring and modelling landscape dynamics

International audienceChanges in land cover and land use are among the most pervasive and important sources of recent alterations of the Earth's land surface.This special issue also presents new directions in modelling landscape dynamics. Agent-based models have primarily been used to simulate local land use and land cover changes processes with a focus on decision making (Le 2008; Matthews et al. 2007; Parker et al. 2003; Bousquet and Le Page 2001)

Quantifying garnet-melt trace element partitioning using lattice-strain theory: New crystal-chemical and thermodynamic constraints

Many geochemical models of major igneous differentiation events on the Earth, the Moon, and Mars invoke the presence of garnet or its high-pressure majoritic equivalent as a residual phase, based on its ability to fractionate critical trace element pairs (Lu/Hf, U/Th, heavy REE/light REE). As a result, quantitative descriptions of mid-ocean ridge and hot spot magmatism, and lunar, martian, and terrestrial magma oceans require knowledge of garnet-melt partition coefficients over a wide range of conditions. In this contribution, we present new crystal-chemical and thermodynamic constraints on the partitioning of rare earth elements (REE), Y and Sc between garnet and anhydrous silicate melt as a function of pressure (P), temperature (T), and composition (X). Our approach is based on the interpretation of experimentally determined values of partition coefficients D using lattice-strain theory. In this and a companion paper (Draper and van Westrenen this issue) we derive new predictive equations for the ideal ionic radius of the dodecahedral garnet X-site,

Experimental and computational study of trace element distribution between orthopyroxene and anhydrous silicate melts: substitution mechanisms and the effect of iron

Although orthopyroxene (Opx) is present during a wide range of magmatic differentiation processes in the terrestrial and lunar mantle, its effect on melt trace element contents is not well quantified. We present results of a combined experimental and computational study of trace element partitioning between Opx and anhydrous silicate melts. Experiments were performed in air at atmospheric pressure and temperatures ranging from 1,326 to 1,420°C in the system CaO-MgO-A

Agriculture phenology monitoring using NDVI time series based on remote sensing satellites : a case study of Guangdong, China

202305 bckwAccepted ManuscriptRGCOthersPhD scholarship from PolyU Hong KongPublishe