Search results for "Forestry"
showing 10 items of 1998 documents
Monumental trees and their existence value: the case study of an Italian natural park
2015
The paper deals with the evaluation of the existence value of monumental trees in a protected area. Financial resources to be destined for protection interventions have been decreasing more and more, with a high risk of losing this natural heritage. A Contingent Valuation Method (CVM) survey was carried out among the Madonie Park (Sicily, Italy) resident households to evaluate the existence value of monumental trees of the nature trail named "Piano Sempria-Piano Pomo", represented by a population of "Giant hollies" and by 7 other individual trees. These are the main results of the CVM survey: the overall response rate was 40%, individual average WTPs ( Willingness To Pay ) were €12.37 for t…
Simulations of convectively-driven density currents in the Atlas region using a regional model: Impacts on dust emission and sensitivity to horizonta…
2009
[1] During the SAMUM field campaign in southern Morocco in May and June 2006 density currents generated by evaporative cooling after convective precipitation were frequently observed at the Sahara side of the Atlas Mountain chain. The associated strong surface cold-air outflow during such events has been observed to lead to dust mobilization in the foothills. Here a regional model system is used to simulate a density current case on 3 June 2006 and the subsequent dust emission. The model studies are performed with different parameterization schemes for convection, and with different horizontal model grid resolutions to examine to which extent the model system can be used for reproducing dus…
High‐resolution simulations of convective cold pools over the northwestern Sahara
2009
[1] Cooling by evaporation of convective precipitation in the deep and dry subcloud layer over desert regions can generate intense downdrafts and long-lived and extensive atmospheric density currents. The strong gusts at their leading edges can cause so-called haboob dust storms. Despite their importance for the dust cycle, the ability of state-of-the-art numerical weather prediction models to realistically simulate the associated convective cold pools has been investigated very little to date. During the first field campaign of the Saharan Mineral Dust Experiment in southern Morocco in May/June 2006, several density currents were observed. They were triggered by deep moist convection over …
Numerical sensitivity studies on the impact of aerosol properties and drop freezing modes on the glaciation, microphysics, and dynamics of clouds
2006
[1] Numerical simulations were performed to investigate the effects of drop freezing in immersion and contact modes for a convective situation. For the description of heterogeneous drop freezing, new approaches were used considering the significantly different ice nucleating efficiencies of various ice nuclei. An air parcel model with a sectional two-dimensional description of the cloud microphysics was employed. Sensitivity studies were undertaken by varying the insoluble particle types as well as the soluble fraction of the aerosol particles showing the effects of these parameters on drop freezing and their possible impact on the vertical cloud dynamics. The soluble fraction ɛ decides whe…
Analysis of thermally induced flows in the laboratory by geoelectrical 3-D tomography
2010
[1] Many natural bodies as well as materials inside industrial installations, such as the Earth's mantle and the glass inside melting furnaces, exchange matter through convection. These processes result from differences in temperature, density, and chemical concentration. In this analysis, we focus on the visualization of thermally driven flows in the laboratory. In nature and in industrial installations, it is difficult to measure the temperature inside the object of interest directly. We benchmark a new DC-geoelectrical 3-D tomography method for temperature measurements that allows obtaining temperature values without influencing the flow pattern. For verification of the method, we use di…
Dust mobilization due to density currents in the Atlas region: Observations from the Saharan Mineral Dust Experiment 2006 field campaign
2007
[1] Evaporation of precipitation is a ubiquitous feature of dry and hot desert environments. The resulting cooling often generates density currents with strong turbulent winds along their leading edges, which can mobilize large amounts of dust. Mountains support this process by triggering convection, by downslope acceleration of the cool air, and by fostering the accumulation of fine-grained sediments along their foothills through the action of water. For the Sahara, the world's largest dust source, this mechanism has been little studied because of the lack of sufficiently high resolution observational data. The present study demonstrates the frequent occurrence of density currents along th…
Modeling of biomass smoke injection into the lower stratosphere by a large forest fire (Part I): reference simulation
2006
Abstract. Wildland fires in boreal regions have the potential to initiate deep convection, so-called pyro-convection, due to their release of sensible heat. Under favorable atmospheric conditions, large fires can result in pyro-convection that transports the emissions into the upper troposphere and the lower stratosphere. Here, we present three-dimensional model simulations of the injection of fire emissions into the lower stratosphere by pyro-convection. These model simulations are constrained and evaluated with observations obtained from the Chisholm fire in Alberta, Canada, in 2001. The active tracer high resolution atmospheric model (ATHAM) is initialized with observations obtained by r…
Soil Carbon Budget Account for the Sustainability Improvement of a Mediterranean Vineyard Area
2020
Sustainable viticulture is suggested as an interesting strategy for achieving the objectives of global greenhouse gas (GHG) emission reduction in terms of mitigation and adaptation. However, knowledge and quantification of the contribution of sustainable vineyard management on climate change impact are needed. Although it is widely assessed by several authors that the agricultural stage has a great impact in the wine chain, very few studies have evaluated the greenhouse gas emission in this phase including the ability of soil to sequester carbon (C) or the off-farm C loss by erosion. This work aimed to provide a vineyard carbon budget (vCB) tool to quantify the impact of grape production on…
Durum wheat yield uncertainty under different tillage management practices and climatic conditions
2019
Abstract In the field of conservative agriculture, no-till (NT) management has been receiving increasing interest, with 45 million ha of land under no-till management in 1999 to 155 million ha in 2014. Up until now, no-till has only been observed to perform better under rainfed conditions, especially in dry climates mainly because the reduced tillage system retains more soil moisture. However, the adoption of alternative agricultural practices (NT) can be improved only if uncertain and consequent assumption of risk is well known and accepted. For these reasons, the aim of this research is (i) to define durum wheat suitability under NT soil management in terms of yield success probability an…
Derivation of high-resolution leaf area index maps in support of validation activities: Application to the cropland Barrax site
2009
The validation of coarse satellite-derived products from field measurements generally relies on up-scaling the field data to the corresponding satellite products. This question is commonly addressed through the generation of a reference high-resolution map of an area covering several moderate resolution pixels. This paper describes a method by which reference leaf area index (LAI) maps can be generated from ground-truth LAI measurements. The method is based on a multivariate ordinary least squares (OLS) algorithm which uses an iteratively re-weighted least squares (IRLS) algorithm. It provides an empirical relationship (i.e. a transfer function) between in situ measurements and concomitant …