3,333 research outputs found

    Measurements of rainfall rate, drop size distribution, and variability at middle and higher latitudes: application to the combined DPR-GMI algorithm

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    The Global Precipitation Measurement mission is a major U.S.–Japan joint mission to understand the physics of the Earth’s global precipitation as a key component of its weather, climate, and hydrological systems. The core satellite carries a dual-precipitation radar and an advanced microwave imager which provide measurements to retrieve the drop size distribution (DSD) and rain rates using a Combined Radar-Radiometer Algorithm (CORRA). Our objective is to validate key assumptions and parameterizations in CORRA and enable improved estimation of precipitation products, especially in the middle-to-higher latitudes in both hemispheres. The DSD parameters and statistical relationships between DSD parameters and radar measurements are a central part of the rainfall retrieval algorithm, which is complicated by regimes where DSD measurements are abysmally sparse (over the open ocean). In view of this, we have assembled optical disdrometer datasets gathered by research vessels, ground stations, and aircrafts to simulate radar observables and validate the scattering lookup tables used in CORRA. The joint use of all DSD datasets spans a large range of drop concentrations and characteristic drop diameters. The scaling normalization of DSDs defines an intercept parameter NW, which normalizes the concentrations, and a scaling diameter Dm, which compresses or stretches the diameter coordinate axis. A major finding of this study is that a single relationship between NW and Dm, on average, unifies all datasets included, from stratocumulus to heavier rainfall regimes. A comparison with the NW–Dm relation used as a constraint in versions 6 and 7 of CORRA highlights the scope for improvement of rainfall retrievals for small drops (Dm lt; 1 mm) and large drops (Dm gt; 2 mm). The normalized specific attenuation–reflectivity relationships used in the combined algorithm are also found to match well the equivalent relationships derived using DSDs from the three datasets, suggesting that the currently assumed lookup tables are not a major source of uncertainty in the combined algorithm rainfall estimates

    VERTOSOILS AND VERTIC SOILS FROM OLTENIA AND THEIR MAIN CROPPING FEATURES

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    The vertosols occupy a large area in the Central zone of Oltenia. They are soils that were formed on clay bedrock represented by swelling clays of montmorillonite that have the property to enlarge very much its volume in contact with water and to contract very strongly when dry, during drought periods. This property of montmorillonite as bedrock determine in the mass of the soil the apparition of cracks from several mm to several cm on horizontal and from several cm to several meters on vertical. The vertosols are present in complex with other vertic soils as vertic preluvosols and vertic luvosols. All these soils have a high clay content, they are compacted, they have a low water and air permeability. Generally, they are profound soils and manifest levigation and stagnogleysation processes having average – low fertility

    WINTER EXTREME EVENTS – ROMANIAN CARPATHIAN AVALANCHES

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    The study presents a statistics of avalanche cases recorded in Romanian Carpathians over the years, most of them since February 2004, when the National Meteorological Administration program for snow and avalanches started, but also from Mountain Rescue Teams, various articles or works. The purpose of this paper is to analyze the meteorological context in which these phenomena occurred. Similar conditions in wich avalanches were triggered are also presented, as basis for future data comparison and work in avalanche risk estimation. Classical methods of meteorological study were used: the evolution of key meteorological parameters over the territory of our country, the barometric topographic maps from ground level and altitude (850 and 500 hPa level), that were taken from the archives of the National Administration of Meteorology, and the GFS model (www.wetter3.de). The study is part of Project Snowball, which aims to inventory the cases of avalanches previously known in our country and favorable conditions of release, to better estimate the risk of avalanches and minimize the effects it could have on the environment and people. Acknowledgement: „The research leading to these results has received funding from EEA Financial Mecanism 2009 - 2014 under the project contract no 19SEE/201

    Localised and nonlocalised structures in nonlinear lattices with fermions

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    We discuss the quasiclassical approximation for the equations of motions of a nonlinear chain of phonons and electrons having phonon mediated hopping. Describing the phonons and electrons as even and odd grassmannian functions and using the continuum limit we show that the equations of motions lead to a Zakharov-like system for bosonic and fermionic fields. Localised and nonlocalised solutions are discussed using the Hirota bilinear formalism. Nonlocalised solutions turn out to appear naturally for any choice of wave parameters. The bosonic localised solution has a fermionic dressing while the fermionic one is an oscillatory localised field. They appear only if some constraints on the dispersion are imposed. In this case the density of fermions is a strongly localised travelling wave. Also it is shown that in the multiple scales approach the emergent equation is linear. Only for the resonant case we get a nonlinear fermionic Yajima-Oikawa system. Physical implications are discussed.Comment: 7 pages, LaTeX, no figures. to appear in Europhysics Latter

    THE INFLUENCE OF THE CONTENT ON HUMUS AND CLAY ON THE PSAMOSOIL PROPERTIES IN THE AREA POIANA MARE-DOLJ

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    The humus and clay are the key organic and mineral components that influence the productive capacity of sandy soils. In order to study the influence of these components there were identified spots of land with different contents of humus and clay on the studied sandy soil during the experiment. There have been taken soil samples which were analyzed in laboratory. The soil samples have been taken from 20 cm depth and there were analyzed and interpreted on a scale with 0.5% units for humus and 5% for clay

    Synoptic Conditions Generating Important Snowfalls and Their Relation with Avalanches in 2015-2016 Winter.

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    The paper presents and analyzes variations in weather conditions, meteorological and nivological (snow related) parameters that favored avalanches triggering in Bucegi and FăgăraƟ Mountains during 2015-2016 winter, an area monitored by the program for snow and avalanches within Romanian National Meteorological Administration. Analyzed parameters are measured on daily observations and weekly measurements, at Bñlea-Lac, Vñrful Omu, Sinaia and Predeal meteorological stations and during the campaigns of measurements made within project Snowball, which aims to inventory cases of avalanches previously known in our country and the favorable conditions, for a better avalanche risk estimation and to reduce their effects on the environment and people. Data from daily observations and NCEP reanalysis ground level pressure maps, absolute topography and temperature maps at 500 hPa were used, from http://www.wetter3.de

    EFFICIENCY OF THE TOPOGRAPHIC WORKS FOR DETACHMENT OF A PROPERTY

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    This paper refers to choice efficient ways of preparation topo-cadastral documentation in order to detachment a property and combine classical methods of measuring with elements of GPS technology. Determination of station points was performed by the RTK-Cinematic in real time using real-time differential corrections from the reference station RGN- GNSS integrated, and the contour and detail points of the land was done by polar coordinates method. All operations necessary to obtain the correction of the coordinate, directions and horizontal distances were performed using TopoLT program, based on data from the total station downloading. For the efficiency of the topographic work, required a series of facilities, especially modern devices, GPS receivers, total stations, and performant PCs, appropriate software for data recording and obtain the final products
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