Mario Pereira

Climate and global warming is one of the important issues focused in the Portuguese primary and secondary physical sciences curricula. Several different phenomena, highlighting the impact of human activities on the climate system, are orally presented and discussed with the students. However, we believe that this approach could be complemented with an appropriate selection of experimental/lab demonstrations to illustrate and demonstrate some of these processes of this theme. In our teaching sessions open to the student community, we follow a simple approach which includes a presentation, a discussion and a demonstration of the most important heating/cooling processes of the Earth and its Atmosphere and the influence of the external and internal factors. The earth orbital parameters changes, the energy transfer, balance, spatial and temporal distribution as well as other Atmospheric processes (water phase changes, latent and sensible heat, the role of the wind and ocean currents) are...

Undergraduate and university level students present some difficulties to understand and interpret many of the geosciences concepts, in particular those represented by vector and scalar fields. Our experience reveals that these difficulties are associated with a lack in the development of their abstraction and mental picturing abilities. On the other hand, these students have easy access to communication and information

It has been shown that the extent of burned area in Portugal is controlled by two main atmospheric factors (Pereira et al. 2005): i) a long-term control related to the regime of temperature and precipitation during spring, in the pre-fire season and ii) a short-term control exerted by the occurrence of very intense dry spells in days of extreme synoptic situations during the fire season, in summer. This information has been applied to develop simple multiple linear regression models based on meteorological variables and fire risk indices in the May-August months. For this purpose we use the Portuguese wildfire database which contains detailed information about every fire events occurred in Continental Portugal during the 1980-2000 period and values of the meteorological variables for the same period. The objective of this work is to assess the potential of regional climate change on wildfires in Portugal, using the aforementioned burnt area models using on meteorological data obtain...

In Portugal, as in many other countries of the world, the design of stormwater drainage infrastructure relies on the implicit assumption that the intense precipitation distribution is statistically stationary and based on the intensity-duration-frequency (IDF) curves. However, observed changes in recent past climate and projections for future climate suggest differences in precipitation regime in Portugal, in particular, in what respects to the frequency and intensity of extreme events, thus leading to the need to evaluate the impact of potential climate change on IDF curves. The objective of this study is to assess the potential consequences of climate change in the design of drainage systems for rainwater and hence the need to review rules and legislation on this design, based on a comparative analysis between Intensity-Duration-Frequency (IDF) curves defined in the Regulatory Decree n ° 23/95 of 23rd August, proposed by Matos and Silva (1986), and those obtained with observed dat...

Forest fires are complex events involving both space and time fluctuations. Understanding of their dynamics and pattern distribution is of great importance in order to improve the resource allocation and support fire management actions at local and global levels. This study aims at characterizing the temporal fluctuations of forest fire sequences observed in Portugal, which is the country that holds the largest wildfire land dataset in Europe. This research applies several exploratory data analysis measures to 302,000 forest fires occurred from 1980 to 2007. The applied clustering measures are: Morisita clustering index, fractal and multifractal dimensions (box-counting), Ripley's K-function, Allan Factor, and variography. These algorithms enable a global time structural analysis describing the degree of clustering of a point pattern and defining whether the observed events occur randomly, in clusters or in a regular pattern. The considered methods are of general importance and ...

Encompassing the lands around the Mediterranean Sea, the Mediterranean Basin is associated to Mediterranean forests, woodlands, and scrub. This temperate biome is characterised by rainy and mild winters followed by warm and dry summers that make the region especially prone to the occurrence of a large number of fire events. Meteorological factors play therefore a crucial role in the setting

Active fire information provided by TERRA and AQUA instruments on-board sun-synchronous polar MODIS platform is used to describe fire activity in the Western Mediterranean and to identify and characterize the synoptic patterns of several meteorological fields associated with the occurrence of extreme fire activity episodes (EEs). The spatial distribution of the fire pixels during the period of 2003-2012 leads to the identification of two most affected sub-regions, namely the Northern and Western parts of the Iberian Peninsula (NWIP) and Northern Africa (NAFR). The temporal distribution of the fire pixels in these two sub-regions is characterized by: (i) high and non-concurrent inter- and intra-annual variability with maximum values during the summer of 2003 and 2005 in NWIP and 2007 and 2012 in NAFR; and, (ii) high intra-annual variability dominated by a prominent annual cycle with a main peak centred in August in both sub-regions and a less pronounced secondary peak in March only evident in NWIP region. The 34 EEs identified were grouped according to the location, period of occurrence and spatial configuration of the associated synoptic patterns into 3 clusters (NWIP-summer, NWIP-winter and NAFR-summer). Results from the composite analysis reveal similar fire weather conditions (statistically significant positive anomalies of air temperature and negative anomalies of air relative humidity) but associated with different circulation patterns at lower and mid-levels of the atmosphere associated with the occurrence of EEs in each cluster of the Western Mediterranean region.

ABSTRACT Within the period 1978–2006, climate change and human interferences produced noticeable impacts on the hydrology of a small watershed, known as the Beça River basin. Climate change was characterized by a persistent raise in temperature (+0.78 °C decade−1) and a drop in the annual rainfall (−300 mm decade−1). Human interferences included the construction of a dam for electric power generation, in 1998, and since then the transference of Beça River flows from the dam lake to the adjacent Tâmega River. The impacts on catchment hydrology comprised a decline of aquifer hydraulic conductivity and effective porosity, by approximately one order of magnitude, related to a water table lowering of about 17 m within the bedrock aquifer composed of weathered and fractured Hercynian granites and Paleozoic metassediments and of saprolite layers derived therefrom. Aquifer property estimates were compared across spatial scales, namely the Beça River and the nested sub-basins scale. Sub-basin aquifers are more porous and permeable than the basin aquifer because corresponding hydraulic circuits are shallower. Comparisons were also made between aquifer properties derived from measured and simulated stream flows, which revealed effects of modeling uncertainties on the results. River flows also suffered a substantial decrease in the course of climate change and human interference, especially the overland flows (4/5 decrease) and the base flows (2/3 decrease). The inter flows were less affected (1/3 decrease) because they were partly fed with water from the aquifer storage, which in turn underwent depletion. The hydrologic changes in the Beça River basin anticipate important impacts on the local use of natural water. In this context, the aforementioned water table lowering may have caused limited access to shallow groundwater for activities such as crop irrigation from dug wells, whereas the severe decline in overland flows and base flows had certainly reduced the availability of surface water for the refilling of dam lakes and of groundwater for the supply of public and private boreholes.

ABSTRACT We address Bizarro's comment on a paper by Anacleto (2011 Eur. J. Phys. 32 279). Bizarro claims that (i) Anacleto's approach is either incomplete or incorrect; (ii) one problem is the definition of dissipative work; and (iii) additional ambiguities and misconceptions may stem from his explanations. We contend that (i) both authors present exactly the same definition of dissipative work; and (ii) it is possible to obtain a more general expression to evaluate the entropy change that comprises the expressions developed by both authors—indicating that Anacleto's approach is correct and coherent, and that the criticism of the paper is therefore unfounded.

Energy is one of the worlds most challenging problems, and power systems are an important aspect of energy-related issues. The Handbook of Power Systems contains state-of-the-art contributions on power systems modeling. In particular, it covers topics like operation planning, expansion planning, transmission and distribution modeling, computing technologies in energy systems, energy auctions, risk management, market regulation, stochastic programming in energy, and forecasting in energy. The book is separated into ...