Qualidade em agricultura: sistemas de certificação, desafios e perspectivas

Qualidade, quando referida ao sector agrícola, integra toda a cadeia produtiva, desde a provisão de matérias-primas até ao consumo e pode ser vista na óptica do produtor e do consumidor. Os sistemas de garantia e certificação da qualidade existentes na União Europeia, baseados numa abordagem holística, são particularmente complexos e variados, pela diversidade de consumidores existentes. A maioria aplica-se a um mercado diferenciado e apenas um reduzido número e muito diversificado vai além das normas legais, visando a diferenciação dos produtos e a manutenção de determinados padrões de qualidade. O seu desenvolvimento é influenciado por medidas de políticas distintas e, factores económicos e sociodemográficos. Podem classificar- se em função do objecto (produtos ou processos), dos objectivos (consumidor final ou os diferentes intervenientes na cadeia de comercialização alimentar), o conteúdo (rastreabilidade na origem ou modo de produção), os promotores (públicos ou privados), o contexto (local, regional, nacional ou internacional) e, o número de etapas envolvidas na cadeia agro-alimentar

Assessing the transferability of the regional climate model REMO to different COordinated Regional Climate Downscaling EXperiment (CORDEX) Regions

The transferability of the regional climate model REMO with a standard setup over different regions of the world has been evaluated. The study is based on the idea that the modeling parameters and parameterizations in a regional climate model should be robust to adequately simulate the major climatic characteristic of different regions around the globe. If a model is not able to do that, there might be a chance of an “overtuning” to the “home-region”, which means that the model physics are tuned in a way that it might cover some more fundamental errors, e.g., in the dynamics. All simulations carried out in this study contribute to the joint effort by the international regional downscaling community called COordinated Regional climate Downscaling EXperiment (CORDEX). REMO has been integrated over six CORDEX domains forced with the so-called perfect boundary conditions obtained from the global reanalysis dataset ERA-Interim for the period 1989 to 2008. These six domains include Africa, Europe, North America, South America, West Asia and the Mediterranean region. Each of the six simulations was conducted with the identical model setup which allows investigating the transferability of a single model to regions with substantially different climate characteristics. For the consistent evaluation over the different domains, a new evaluation framework is presented by combining the Köppen-Trewartha climate classification with temperature-precipitation relationship plots and a probability density function (PDF) skill score method. The evaluation of the spatial and temporal characteristics of simulated precipitation and temperature, in comparison to observational datasets, shows that REMO is able to simulate the mean annual climatic features over all the domains quite reasonably, but still some biases remain. The regions over the Amazon and near the coast of major upwelling regions have a significant warm bias. Wet and dry biases appear over the mountainous regions and East Africa, respectively. The temperature over South America and precipitation over the tundra and highland climate of West Asia are misrepresented. The probable causes leading to these biases are discussed and ideas for improvements are suggested. The annual cycle of precipitation and temperature of major catchments in each domain are also well represented by REMO. The model has performed well in simulating the inter- and intra-seasonal characteristics of different climate types in different regions. Moreover, the model has a high ability in representing the general characteristics of different climate types as measured by the probability density function (PDF) skill score method. Although REMO seems to perform best over its home domain in Europe (domain of development and testing), the model has simulated quite well the climate characteristics of other regions with the same set of parameterization options. Therefore, these results lead us to the conclusion that REMO is well suited for long-term climate change simulations to examine projected future changes in all these regions

The Regional Climate Change Hyper‐Matrix Framework

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95340/1/eost16593.pd

The first multi-model ensemble of regional climate simulations at kilometer-scale resolution. Part I: Evaluation of precipitation

Here we present the first multi-model ensemble of regional climate simulations at kilometer-scale horizontal grid spacing over a decade long period. A total of 23 simulations run with a horizontal grid spacing of ∼ 3 km, driven by ERA-Interim reanalysis, and performed by 22 European research groups are analysed. Six different regional climate models (RCMs) are represented in the ensemble. The simulations are compared against available high-resolution precipitation observations and coarse resolution (∼ 12 km) RCMs with parameterized convection. The model simulations and observations are compared with respect to mean precipitation, precipitation intensity and frequency, and heavy precipitation on daily and hourly timescales in different seasons. The results show that kilometer-scale models produce a more realistic representation of precipitation than the coarse resolution RCMs. The most significant improvements are found for heavy precipitation and precipitation frequency on both daily and hourly time scales in the summer season. In general, kilometer-scale models tend to produce more intense precipitation and reduced wet-hour frequency compared to coarse resolution models. On average, the multi-model mean shows a reduction of bias from ∼ −40 at 12 km to ∼ −3 at 3 km for heavy hourly precipitation in summer. Furthermore, the uncertainty ranges i.e. the variability between the models for wet hour frequency is reduced by half with the use of kilometer-scale models. Although differences between the model simulations at the kilometer-scale and observations still exist, it is evident that these simulations are superior to the coarse-resolution RCM simulations in the representing precipitation in the present-day climate, and thus offer a promising way forward for investigations of climate and climate change at local to regional scales. © 2021, The Author(s)

The first multi-model ensemble of regional climate simulations at kilometer-scale resolution, part I: evaluation of precipitation

Here we present the first multi-model ensemble of regional climate simulations at kilometer-scale horizontal grid spacing over a decade long period. A total of 23 simulations run with a horizontal grid spacing of ∼3 km, driven by ERA-Interim reanalysis, and performed by 22 European research groups are analysed. Six different regional climate models (RCMs) are represented in the ensemble. The simulations are compared against available high-resolution precipitation observations and coarse resolution (∼ 12 km) RCMs with parameterized convection. The model simulations and observations are compared with respect to mean precipitation, precipitation intensity and frequency, and heavy precipitation on daily and hourly timescales in different seasons. The results show that kilometer-scale models produce a more realistic representation of precipitation than the coarse resolution RCMs. The most significant improvements are found for heavy precipitation and precipitation frequency on both daily and hourly time scales in the summer season. In general, kilometer-scale models tend to produce more intense precipitation and reduced wet-hour frequency compared to coarse resolution models. On average, the multi-model mean shows a reduction of bias from ∼ −40% at 12 km to ∼ −3% at 3 km for heavy hourly precipitation in summer. Furthermore, the uncertainty ranges i.e. the variability between the models for wet hour frequency is reduced by half with the use of kilometer-scale models. Although differences between the model simulations at the kilometer-scale and observations still exist, it is evident that these simulations are superior to the coarse-resolution RCM simulations in the representing precipitation in the present-day climate, and thus offer a promising way forward for investigations of climate and climate change at local to regional scales

Utilización de hidrotalcitas en la producción de biodiesel

Comunicación presentada en las III Jornadas sobre la Enseñanza de la Química "Química para un mundo sostenible", Valencia, 1-4 octubre 2009.El presente trabajo está orientado específicamente, dentro del uso de la biomasa como fuente de energía, al estudio de la producción de un biocarburante denominado biodiesel, a partir de la transesterificación de aceite vegetal y de aceite proveniente de fritura con una alto índice de acidez (superior al 1 % máximo establecido para una generación óptima de este biocarburante). En este caso, el aceite de fritura no ha sido sometido a ningún proceso previo para eliminar el problema añadido de su acidez elevada o su contenido de agua, hecho que simplifica sustancialmente el proceso utilizando este tipo de materias primas.Vicerrectorado de Investigación, Desarrollo e Innovación de la Universidad de Alicante (proyecto GRE 07-8P)

Using hydrotalcite for biodiesel production

Different parameters that can modify the extension of the transesterification reaction have been evaluated, such as, reaction temperature, agitation speed, methanol:oil molar ratio, percentage of solid catalyst presents in the reaction medium and percentage of sodium incorporated into the catalyst used.In the present work, a new heterogeneous catalyst for oil transesterification with methanol has been developed. The catalyst is based on the introduction of sodium in calcined hydrotalcite. Two different raw materials have been used in order to determine the useful of this new catalyst: sunflower oil and used frying oil from a university restaurant.Universidad de Alicante (project GRE 07-8P