Search results for "Spatial Distribution"
showing 10 items of 180 documents
Bias correction of dynamically downscaled precipitation to compute soil water deficit for explaining year-to-year variation of tree growth over north…
2017
This paper documents the accuracy of a post-correction method applied to precipitation regionalized by the Weather Research and Forecasting (WRF) Regional Climate Model (RCM) for improving simulated rainfall and feeding impact studies. The WRF simulation covers Burgundy (northeastern France) at a 8-km resolution and over a 20-year long period (1989–2008). Previous results show a strong deficiency of the WRF model for simulating precipitation, especially when convective processes are involved. In order to reduce such biases, a Quantile Mapping (QM) method is applied to WRF-simulated precipitation using the mesoscale atmospheric analyses system SAFRAN («Système d'Analyse Fournissant des Rense…
Sentinel-3/FLEX Biophysical Product Confidence Using Sentinel-2 Land-Cover Spatial Distributions
2021
The estimation of biophysical variables from remote sensing data raises important challenges in terms of the acquisition technology and its limitations. In this way, some vegetation parameters, such as chlorophyll fluorescence, require sensors with a high spectral resolution that constrains the spatial resolution while significantly increasing the subpixel land-cover heterogeneity. Precisely, this spatial variability often makes that rather different canopy structures are aggregated together, which eventually generates important deviations in the corresponding parameter quantification. In the context of the Copernicus program (and other related Earth Explorer missions), this article propose…
Spatial distribution of aerosol microphysical and optical properties and direct radiative effect from the China Aerosol Remote Sensing Network
2019
Multi-year observations of aerosol microphysical and optical properties, obtained through ground-based remote sensing at 50 China Aerosol Remote Sensing Network (CARSNET) sites, were used to characterize the aerosol climatology for representative remote, rural, and urban areas over China to assess effects on climate. The annual mean effective radii for total particles (ReffT) decreased from north to south and from rural to urban sites, and high total particle volumes were found at the urban sites. The aerosol optical depth at 440 nm (AOD440 nm) increased from remote and rural sites (0.12) to urban sites (0.79), and the extinction Ångström exponent (EAE440–870 nm) increased fro…
Spatial distribution of temperature trends in Sicily
2013
Climate change resulting from the enhanced greenhouse effect is expected to have great impacts on hydrological cycle and consequently on ecosystems. The effects of climate variability have direct implications on water management, as water availability is related to changes in temperature and precipitation regimes. At the same time, this kind of alterations drives ecological impacts on flora and fauna. For these reasons, many studies have been carried out to investigate the existence of some tendency in temperature and/or precipitation series in different geographic domains. In order to verify the hypothesis of temperature increase in Sicily (Italy), temperature data from about 80 spatially …
Heavy daily precipitation distribution in east-central Franceand west European meteorological patterns
2000
Principal Component Analysis is used to link the spatial distribution of Heavy Daily Precipitation (HDP) in East-Central France with meteorological patterns of the Meteo-France automatic classification, which takes into account 15 different meteorological parameters (e.g. geopotential heights at different levels, humidities, pseudo-adiabatic temperatures) over Western Europe. Every parameter is classified in 10 classes, or synoptic patterns. The annual PCA shows 3 dominant modes of HDP distribution, explaining more than 90% of the total variance. Associated atmospheric situations are obtained by using the scores of the 150 classes (10 per meteorological parameter). Other PCAs (i.e., half-an…
Trend Analysis of Global MODIS-Terra Vegetation Indices and Land Surface Temperature Between 2000 and 2011
2013
Previous works have shown that the combination of vegetation indices with land surface temperature (LST) improves the analysis of vegetation changes. Here, global MODIS-Terra monthly data from 2000 to 2011 were downloaded and organized into LST, NDVI (Normalized Difference Vegetation Index) and EVI (Enhanced Vegetation Index) time series. These time series were then corrected from cloud and atmospheric residual contamination through the IDR (iterative Interpolation for Data Reconstruction) method. Then, statistics were retrieved from both corrected time series, and the YLCD (Yearly Land Cover Dynamics) approach has been applied to data sources (NDVI-LST and EVI-LST) to analyze changes in th…
Rainfall and Sea-Breeze Circulation over South-Western France
1997
South-western France (Aquitaine region) has an oceanic temperate climate but some climatic peculiarities (irregular patterns in isohyets) are observed along a narrow coastal belt. The spatial distribution of winter and summer precipitation shows a ‘rainy strip’ located around 20 to 40 km inland. Three features allow an explanation of this distribution: synoptic flow, sea-breeze and heterogeneous land roughness (presence of the Foret des Landes). To take into account the impact of these features, numerical simulations are examined using a three-dimensional mesoscale model. The occurrence of the forest increases the possibility of precipitation during irregular patterns in isohyets. © 1997 by…
Spatial distribution of the precipitation in Dobruja (Romania/Black Sea)
2000
An original dataset for the Dobruja, a low plateau region of southeastern Romania, is used to perform a statistical study of the spatial distribution of rainfall at annual and seasonal time-scales. A principal component analysis (PCA) is carried out to identify the precipitation regimes. The high eigenvalue of PC1 attests of the prevailing temperate-continental regime, with a relatively dry winter opposed to a late spring and early summer rainfall maximum. PC2 shows the specific pattern of the coast, with a small secondary maximum in November. In spite of the relatively flat topography, annual rainfall is characterized by a strong gradient between the coast and the interior. Particularly lo…
Reactive halogen chemistry in volcanic plumes
2007
[1] Bromine monoxide (BrO) and sulphur dioxide (SO2) abundances as a function of the distance from the source were measured by ground-based scattered light Multiaxis Differential Optical Absorption Spectroscopy (MAX-DOAS) in the volcanic plumes of Mt. Etna on Sicily, Italy, in August–October 2004 and May 2005 and Villarica in Chile in November 2004. BrO and SO2 spatial distributions in a cross section of Mt. Etna's plume were also determined by Imaging DOAS. We observed an increase in the BrO/SO2 ratio in the plume from below the detection limit near the vent to about 4.5 × 10−4 at 19 km (Mt. Etna) and to about 1.3 × 10−4 at 3 km (Villarica) distance, respectively. Additional attempts were …
The orthogonal structure of Monsoon rainfall variation over Sri Lanka
1992
The spatial organization of Monsoon rainfall over Sri Lanka is examined using Orthogonal Factor Analysis (OFA) on long-term mean monthly rainfall data. Three types of orthogonal structure of Monsoon regime in Sri Lanka have been identified. Interpretation of orthogonal factor scores revealed that a large amount of rainfall occurs from March to October in the southwestern parts of Sri Lanka, from December to February in the eastern parts, and in November in the northern and mid-western parts which are all represented by high positive factor scores. Orthogonal factor scores for the first three factors account for 93.6% of the total variance of mean monthly rainfall and clearly indicate that t…