Integrated crop-livestock-forestry systems as potential carbon sinks.

Mixed farming systems have great potential to combine food production with environmental services, including climate change mitigation and biodiversity preservation. This study contributed to the evaluation of integrated crop-livestock (ICL) and crop-livestock-forestry (ICLF) production systems from the point of view of their potential for carbon (C) sequestration in the soil and in the production system as a whole

Study of the urban heat island in Lecce (Italy) by means of ADMS and ENVI-met

The Urban Heat Island (UHI) phenomenon is associated to a cascade of effects on citizens' health, energy consumptions and air quality. Accurate local scale UHI numerical predictions are particularly relevant for the achievement of a sustainable urban planning. In this paper, we evaluate the performance of two different modelling techniques to predict temperature distribution within the urban environment. The diagnostic integral-semi-Gaussian model ADMS-Temperature and Humidity Model and the prognostic Computational Fluid Dynamics (CFD) based model ENVI-met were used and results were validated against field measurements collected during summer 2012 in four different neighbourhoods of Lecce, an Italian medium size city. Results suggested that even if the entire building morphometry and green areas were carefully reproduced within the CFD-based model and only parameterized within the integral model, the level of complications appeared to be not essential in temperature predictions. As a consequence the integral model resulted to be more effective for a fast and accurate assessment of air temperature distribution within the city

Study of the urban heat island in Lecce (Italy) by means of ADMS and ENVI-met

The Urban Heat Island (UHI) phenomenon is associated to a cascade of effects on citizens’ health, energy consumptions and air quality. Accurate local scale UHI numerical predictions are particularly relevant for the achievement of a sustainable urban planning. In this paper, we evaluate the performance of two different modelling techniques to predict temperature distribution within the urban environment. The diagnostic integral-semi-Gaussian model ADMS-Temperature and Humidity Model and the prognostic Computational Fluid Dynamics (CFD) based model ENVI-met were used and results were validated against field measurements collected during summer 2012 in four different neighbourhoods of Lecce, an Italian medium size city. Results suggested that even if the entire building morphometry and green areas were carefully reproduced within the CFD-based model and only parameterized within the integral model, the level of complications appeared to be not essential in temperature predictions. As a consequence the integral model resulted to be more effective for a fast and accurate assessment of air temperature distribution within the city

The effects of trees on micrometeorology in a medium-size mediterranean city: In situ experiments and numerical simulations

This study analyses the aerodynamic effects of trees on local meteorological variables through in situ measurements and Computational Fluid Dynamics (CFD) simulations. Measurements are taken in the inner core of a medium-size Mediterranean city (Lecce, IT) where two adjacent street canyons of aspect ratio H/W?1 (where H is the average building height and W is the average width of the street) with and without trees are investigated. Building fa\ue7ades and ground temperatures are estimated from infrared (IR) images, while flow and turbulence are measured through three ultrasonic anemometers placed at different heights close to a building fa\ue7ade at half length of the canyon. Tree crown porosity is evaluated through the Leaf Area Index (LAI) measured by a ceptometer. Numerical simulations are made using a CFD code equipped with the Reynolds Stress Model (RSM) for the treatment of turbulence. Overall, the analysis of measurements shows that trees considerably reduce the longitudinal wind speed up to 30%. Trees alter the typical diurnal cycle of surface and air temperature within the canyon, suggesting that in nocturnal hours the trapping of heat is more important than the power of passive cooling through evapo-transpiration. Comparative numerical simulations provide further evidence that flow velocity reduces in presence of trees and although the typical wind channeling observed without trees is still maintained, trees enhance the formation of a corner vortex leading to reverse flow at the openings of the street. The reduction of the exchange of momentum between the canyon and the atmosphere above, shown by the measurements in presence of trees is confirmed by numerical simulations

Validation of temperature-perturbation and CFD-based modelling for the prediction of the thermal urban environment: The Lecce (IT) case study

This paper discusses the performance of the temperature perturbation-type ADMS-Temperature and Humidity Model (ADMS-TH) and the Computational Fluid Dynamics (CFD)-based model ENVI-met for the prediction of urban air temperature using measurements collected in the city of Lecce (IT) in summer 2012. The goal is to identify the most important factors influencing numerical predictions. Direct comparisons with measured data and statistical indices show that modelled results are within the range of acceptance. Daily trends are well captured although an underestimation of maximum temperature is observed. In ADMS-TH this is due to an underestimation of sensible heat fluxes during daytime, while in ENVI-met it can be attributed to an underestimation of turbulent momentum and thermal diffusivity. Overall, ADMS-TH did predict the temperature cycle with higher accuracy than ENVI-met and its performance was particularly good during the night. ENVI-met required an ad-hoc tuning of surface boundary conditions to predict nocturnal cooling, satisfactorily

Long term performance, losses and efficiency analysis of a 960 kWp photovoltaic system in the Mediterranean climate

This paper investigates the performance of a 960 kWP photovoltaic (PV) system, located in southern Italy. Monitoring data over a 43 months period are used to evaluate the monthly average of energy yields, losses and efficiency. The performance ratio and the capacity factor were 84.4% and 15.6%, respectively. The yearly average module efficiency was 15.3% and the system efficiency was 14.9%, whereas the capture and system losses were 0.6 h/day and 0.1 h/day respectively. The degradation rate of the PV system, after continuous outdoor exposure, has been estimated at about 1.48%/year by applying the Classical Seasonal Decomposition (CSD) method. A comparison in terms of degradation rate is made with other PV plants installed in different climates to address the need of standard methods to determine this crucial parameter. The actual performance of the studied PV system is compared with the expected outcomes by using two widely used PV simulation tools, SAM and PVsyst. A detailed difference analysis is carried out to evaluate the accuracy of the SAM and PVsyst models. Results show that the yearly average energy injected into the grid was under-estimated by 3.0% by SAM and by 3.3% by PVsyst, but overall PVsyst outperforms the SAM tool. Results provide reliable data on the plant and demonstrate its good performance compared to other plants located in the same climate. The results can be used to improve the prediction of the performance of future PV of systems in the Mediterranean climate, and also provide a useful dataset for comparative studie

Study of the urban heat island in Lecce (Italy) by means of ADMS and ENVI-MET

The urban heat island (UHI) phenomenon may produce several cascade effects on citizens' health, energy consumption and air quality. Numerical modelling is recognised to be a powerful tool for the analysis of the UHI, although the question of which model to use (as implied in the 'fit-forpurpose' approach) much depends on the application and on the result of satisfactory validation against field measurements. In this paper, two different modelling approaches are applied, namely the integral-semi-Gaussian model ADMS-TH and the CFD-based model ENVI-met, to assess the UHI phenomenon in a city of south Italy (Lecce). Modelling results are validated against field measurements collected during summer 2012. The results suggest that the integral model has the ability of capturing the UHI cycle at city scale, while CFD modelling did not provide any substantial improvements in terms of local geometric effects on temperature distribution