1,721,112 research outputs found
Evaluation of the performances of the fire simulators FOREFIRE and FARSITE in Mediterranean areas
No full textPossibile uso dell’etilene da ferita, prodotto dalle foglie di Cistus monspeliensis e Pistacia lentiscus, come indicatore biochimico dello stress idrico per la vegetazione mediterranea in condizioni naturali
No full text
An optimal Cellular Automata algorithm for simulating wildfire spread
No full textRaster-based methods for simulating wildfire spread are computationally more efficient than vectorbased
approaches. In spite of this, their success has been limited by the distortions that affect the fire
shapes. This work presents a Cellular Automata (CA) approach that is able to mitigate the problem of
distorted fire shapes thanks to a redefinition of the spread velocity, where the equations generally used
in vector-based approaches are modified by means of some correction factors. A numerical optimization
approach is used to find the optimal values for the correction factors. The results are compared to the
ones given by two Cellular Automata simulators from the literature under homogeneous conditions.
According to this work, the proposed approach provides better results, in terms of accuracy, at a comparable
computational cost. The proposed approach has then been compared to Farsite, a vector-based
fire-spread simulator, under realistic slope and wind conditions, producing equivalent results in a
reduced computational time
VULCAN: a European field scale manipulation project to assess the vulnerability of shrubland ecosystems under climatic changes
No full textEstimate of mass and energy fluxes over grapevine using eddy covariance technique. 664: 631-638
No full textAbstract
The impacts of weather on carbon storage in tree and vine crops are inadequately investigated because of the small area planted in comparison to the large extent of forest ecosystems. In the last decade, the eddy covariance technique (EC) has become a standard for estimating carbon and water vapor exchanges in all international flux networks. EC is a direct measurement of the upward and downward fluxes that uses high frequency measurements of vertical component of the wind speed and scalars. This study assessed the energy budget components and carbon and water vapor fluxes in two vineyards in Italy. An EC system was used to monitor 15-min values of carbon dioxide (Fc), water vapor (LE), and sensible heat (H) fluxes above the vegetation. Flux data were taken in August of 2002 in Tuscany, Italy, and in July of 2003 in Sardinia, Italy. In addition, net radiation (Rn) and soil heat flux (G) data were collected. The results of the energy balance closure indicated good accuracy of the data set. Rn was partitioned more toward H and less toward lambda E most of the time, depending on weather conditions and irrigation applications. The daytime Fc values ranged between -8 and -15 mu mol CO2 m(-2) s(-1). The daily net C budget was in about 2.14 g m(-2) d(-1) in Tuscany and 4.32 g m(-2) d(-1) in Sardinia showing that the vineyards were sinks for C
2004. A daily water balance estimate for climate risk evaluation at a local scale
No full textAbstract
A methodology for calculating a soil-water balance based on climatological and pedological data of Sardinia (Italy) is presented. Daily temperature and rainfall data from reference period 1971-2000 were spatially interpolated on a 10 km x 10 km cell grid to obtain a set of homogeneously distributed values. Pedological information of Sardinian soils were used to characterize the entire territory of Sardinia in terms of available water content (AWC) and soil depth. Reference evapotranspiration values (ETo) were estimated using the Hargreaves method and actual evapotranspiration estimates (ETa) were calculated as function of soil water content for each grid cell. A simplified soil water balance was calculated for each grid point and year to determine the average daily soil water content over the thirty-year period. Climatic risk was evaluated considering the number of days when soil water content was below 50% of available water content threshold for each year of the 1971-2000 period. Results show a wide variability of interannual climatic and water deficit conditions throughout the region. Maps of spatial distribution of drought conditions show that the dryest years were from 1996 to 2000. During this 5-year period, about 60% of the Sardinian territory was affected by severe climatic conditions which determined high climatic risk for agricultural areas
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