Glacial and periglacial data integration in a GIs: methodology used in the Serra da Estrela, Portugal

The methodology applied in the research in Serra da Estrela (Portugal) is to integrate glacial and periglacial geomorphological data in a Geographical Information System and a Database Management System. The main objective of the procedure is to make use of low cost software for geospatial data integration, statistical analysis and production of geomorphological mag. The digital storage format provides the means for fast access and easy transportation of the data during field campaigns. It is also a very useful way to store the geomorphological data, so it can be used in the future by other researchers working in the area.info:eu-repo/semantics/publishedVersio

Evaluation of the ground surface Enthalpy balance from bedrock temperatures (Livingston Island, Maritime Antarctic)

The annual evolution of the ground temperatures from Incinerador borehole in Livingston Island (South Shetlands, Antarctic) is studied. The borehole is 2.4 m deep and is located in a massive quartzite outcrop with negligible water content, in the proximity of the Spanish Antarctic Station Juan Carlos I. In order to model the movement of the 0◦C isotherm (velocity and maximum depth) hourly temperature profiles from: (i) the cooling periods of the frost season of 2000 to 2005, and (ii) the warming periods of the thaw season of 2002–2003, 2003–2004 and 2004–2005, were studied. In this modelling approach, heat gains and losses across the ground surface are assumed to be the causes for the 0◦C isotherm movement. A methodological approach to calculate the ground Enthalpy change based on the thermodynamic analysis of the ground during the cooling and warming periods is proposed. The Enthalpy change into the rock is equivalent to the heat exchange through the ground surface during each season, thus enabling to describe the interaction groundatmosphere and providing valuable data for studies on permafrost and periglacial processes. The bedrock density and thermal conductivity are considered to be constant and initial isothermal conditions at 0◦C are assumed (based in collected data and local meteorological conditions in this area) to run the model in the beginning of each season. The final stages correspond to the temperatures at the end of the cooling and warming periods (annual minima and maxima). The application of this method avoids error propagation induced by the heat exchange calculations from multiple sensors using the Fourier method.info:eu-repo/semantics/publishedVersio

New observations indicate the possible presence of permafrost in North Africa (Djebel Toubkal, High Atlas, Morocco)

Relict and present-day periglacial features have been reported in the literature for the upper reaches of the High Atlas mountains, which is the highest range in North Africa (Djebel Toubkal – 4167 m a.s.l.). A lobate feature in the Irhzer Ikhibi south at 3800 m a.s.l. has been previously interpreted as an active rock glacier, but no measurements of ground or air temperatures are known to exist for the area. In order to assess the possible presence of permafrost, we analyse data from June 2015 to June 2016 from two air temperature measurement sites at 2370 and 3210 m a.s.l. and from four ground surface temperature (GST) sites at 3220, 3815, 3980 and 4160 m a.s.l. to characterize conditions along an altitudinal gradient along the Oued Ihghyghaye valley to the summit of the Djebel Toubkal. GSTs were collected at 1 h intervals, and the presence of snow cover at the monitoring sites was validated using Landsat 8 and Sentinel-2 imagery. Two field visits allowed for logger installation and collection and for assessing the geomorphological features in the area. The results show that snow plays a major role on the thermal regime of the shallow ground, inducing important spatial variability. The lowest site at 3220 m had a thermal regime characterized by frequent freeze–thaw cycles during the cold season but with few days of snow. When snow settled, the ground surface remained isothermal at 0 ◦C , indicating the absence of permafrost. The highest sites at 3980 and 4160 m a.s.l. showed very frequent freeze–thaw cycles and a small influence of the snow cover on GST, reflecting the lack of snow accumulation due to the wind-exposed settings on a ridge and on the summit plateau. The site located at 3815 m in the Irhzer Ikhibi south valley had a cold, stable thermal regime with GST varying from −4.5 to −6 ◦C from December to March, under a continuous snow cover. The site’s location in a concave setting favours wind-driven snow accumulation and lower incoming solar radiation due to the shading effect of a ridge, inducing the conservation of a thick snow pack. The stable and low GSTs are interpreted as a strong indicator of the probable presence of permafrost at this site, which is an interpretation supported by the presence of lobate and arcuate features in the talus deposits. We present first results and further observations using geophysics, and borehole measurements are foreseen. This is the first time that probable permafrost has been reported from temperature observations in the mountains of North Africa.info:eu-repo/semantics/publishedVersio

Cálculo do efeito de sombra com o Sistema de Informação Geográfica ILWIS 2.1

O estudo da distribuição das áreas potencialmente à sombra, logo, recebendo apenas radiação solar difusa e das áreas expostas à radiação solar directa é um aspecto de grande importância em estudos de climatologia local, e com aplicações directas na fitossociologia, ordenamento do território, agricultura, etc. Também para a geomorfologia e, em especial para a geomorfologia periglaciária, é um dado importante, pois o regime energético, e consequentemente, térmico e higrométrico das áreas na sombra, é substancialmente diferente do regime das áreas expostas à radiação solar directa [...] É apresentada uma metodologia desenvolvida para o SIG ILWIS 2.1 que permite calcular a distribuição das áreas potencialmente à sombra e potencialmente ao sol, partindo de um modelo digital de terreno (DTM) e conhecendo o azimute e altura do sol. Com os mapas assim produzidos, e utilizando um outro algoritmo (ver Felicísimo, 1994 e Meijerink et al., 1994) é possível modelizar a radiação solar directa potencial.info:eu-repo/semantics/publishedVersio

Ground temperature and permafrost distribution in Hurd Peninsula (Livingston Island, Maritime Antarctic): an assessment using freezing indexes and TTOP modelling

The Western Antarctic Peninsula region shows mean annual air temperatures ranging from −4 to −2 °C. Due to its proximity to the climatic threshold of permafrost, and evidence of recent changes in regional air temperatures, this is a crucial area to analyse climate-ground interactions. Freezing indexes and n-factors from contrasting topographic locations in Hurd Peninsula (Livingston Island) are analysed to assess the influence of snow cover on soil's thermal regime. The snow pack duration, thickness and physical properties are key in determining the thermal characteristics and spatial distribution of permafrost. The Temperature at the Top Of the Permafrost (TTOP) model uses freezing and thawing indexes, n-factors and thermal conductivity of the ground, as factors representing ground-atmosphere interactions and provides a framework to understand permafrost conditions and distribution. Eight sites were used to calculate TTOP and evaluate its accuracy. They encompass different geological, morphological and climatic conditions selected to identify site-specific ground thermal regime controls. Data was collected in the freezing seasons of 2007 and 2009 for air, surface and ground temperatures, as well as snow thickness. TTOP model results from sites located between 140 and 275 m a.s.l were very close to observational data, with differences varying from 0.05 to 0.4 °C, which are smaller than instrumental error. TTOP results for 36 m a.s.l confirm that permafrost is absent at low altitude and thermal offsets for rock areas show values between 0.01 and 0.48 °C indicating a small effect of latent heat, as well as of advection.info:eu-repo/semantics/publishedVersio

Land cover classification using high‐resolution aerial photography in Adventdalen, Svalbard

A methodology was tested for high‐resolution mapping of vegetation and detailed geoecological patterns in the Arctic Tundra, based on aerial imagery from an unmanned aerial vehicle (visible wavelength – RGB, 6 cm pixel resolution) and from an aircraft (visible and near infrared, 20 cm pixel resolution). The scenes were fused at 10 and 20 cm to evaluate their applicability for vegetation mapping in an alluvial fan in dventdalen, Svalbard. Ground‐truthing was used to create training and accuracy evaluation sets. Supervised classification tests were conducted with different band sets, including the original and derived ones, such as and principal component analysis bands. The fusion of all original bands at 10 cm resolution provided the best accuracies. The best classifier was systematically the maximum neighbourhood algorithm, with overall accuracies up to 84%. Mapped vegetation patterns reflect geoecological conditioning factors. The main limitation in the classification was differentiating between the classes graminea, moss and Salix, and moss, graminea and Salix, which showed spectral signature mixing. Silty‐clay surfaces are probably overestimated in the south part of the study area due to microscale shadowing effects. The results distinguished vegetation zones according to a general gradient of ecological limiting factors and show that + high‐resolution imagery are excellent tools for identifying the main vegetation groups within the lowland fan study site of dventdalen, but do not allow for detailed discrimination between species.info:eu-repo/semantics/publishedVersio

Low-cost data loggers for air, soil and rock temperature monitoring

Registadores automáticos de temperatura do tipo Tiny Talk II® foram transformados no laboratório do Centro de Estudos Geográficos, com o objectivo de monitorizar as variações de temperatura do ar, rocha e solo. Tratam-se de registadores de 8 bits, com capacidade para armazenar até 1800 dados de temperatura medida a intervalos pré-definidos. A principal vantagem do sistema reside no baixo custo dos instrumentos, na sua pequena dimensão e na simplicidade das adaptações necessárias para que sejam medidos os parâmetros referidos. Descrevem-se na presente nota todos os procedimentos necessários para a construção dos três tipos de sistema de aquisição de dados.Tiny Talk II data loggers were adapted in the laboratory of the Centro de Estudos Geográficos for air, soil and rock temperature monitoring. The loggers are single-channel 8 bit devices with a 2K EEPROM memory that allows the registration of 1,800 temperature records at user-defined intervals. Temperatures are measured by NTC100 thermistors separated by the authors from the data logger for more accurate measurements. Data is transferred from the loggers into a portable computer using a RS-232 cable. It is a low cost system very appropriate for use in rough environmental conditions, particularly in mountain areas. It was successfully tested by the authors in the Antarctic, Pyrenees, Sierra Nevada and Serra da Estrela. The detailed procedures for the construction of three measuring systems are described. The air temperature apparatus is constructed using PVC tubing and protecting cases and is designed for the measurement of air temperatures at 130cm above the ground. The soil temperature monitoring apparatus measures temperatures at 1, 5, 10 and 20cm depth and is based in 4 data loggers protected from moisture and dust in an IP68 case. The rock temperature measuring system is similar to the latter but the sensors are installed in the interior of the rock and isolated using silicon glue.info:eu-repo/semantics/publishedVersio

Promotion of Education in Geosciences and UNESCO Global Geoparks

Considering that Earth is an active planet and that anthropic action contributes to alter the planet's dynamic equilibrium, through the increase of the natural hazards and depletion or destruction of the geological heritage, often for lack of knowledge of its scientific and didactic value, the dissemination of the work developed in Geosciences as well as Education, is of the utmost importance. In this context, the dissemination and teaching of Geosciences gained another dynamic with the creation of Geoparks because, these geographically well-defined territories that possess a remarkable geological heritage, in association with the other elements of the natural and cultural heritage, have as fundamental pillars Geoconservation, Tourism and Education for Sustainability. In this context, the UNESCO Global Geoparks promote the development of educational programs and interpretive resources, contributing to the dissemination of scientific knowledge enabling a greater visibility to Geosciences among the educational community and the general public. The Estrela Aspiring Geopark, which has an area of approximately 2216 km2 and includes 9 municipalities around Estrela, is a territory where sustainable development is sought in an integrated way, based on its geological and geomorphological heritage, of national and international relevance, its biodiversity and its culture, a reflection of the secular adaptation of its communities to this mountain territory. Here we can find important marks of the last glaciation that occurred about 30,000 years ago. This aspiring UNESCO Global Geopark is promoting multidisciplinary educational programs, which include indoor and outdoor activities, aimed at different levels of education (Basic, Secondary and Higher Education), in order to foster direct contact with the geological heritage, thus contributing to the recognition of its importance and consequently to the need for its conservation, since it is only possible to value and preserve what is truly known. The Estrela Aspiring Geopark has also interpretive routes in the field of non-formal education, aimed at the general public, and thus contributing to the dissemination and preservation of the valuable natural and cultural heritage of Estrela, as well as its use in a sustainable way. This article intends to demonstrate the importance of education in the dissemination of scientific knowledge, especially in the field of Geosciences, and to reveal how UNESCO Global Geoparks can be living laboratories, where multiple didactic and learning experiences are developed.info:eu-repo/semantics/publishedVersio

Soil temperatures in an Atlantic high mountain environment: the Forcadona buried ice patch (Picos de Europa, NW Spain)

The present study focuses on the analysis of the ground and near-rock surface air thermal conditions at the Forcadona glacial cirque (2227 m a.s.l.) located in the Western Massif of the Picos de Europa, Spain. Temperatures have been monitored in three distinct geomorphological and topographical sites in the Forcadona area over the period 2006–11. The Forcadona buried ice patch is the remnant of a Little Ice Age glacier located in the bottom of a glacial cirque. Its location in a deep cirque determines abundant snow accumulation, with snow cover between 8 and 12 months. The presence of snow favours stable soil temperatures and geomorphic stability. Similarly to other Cantabrian Mountains, the annual thermal regime of the soil is defined by two seasonal periods (continuous thaw with daily oscillations and isothermal regime), as well as two short transition periods. However, the results showed evidence of a significantly different annual thermal regime at the ground and near-rock surface air. Relatively stable soil thermal regimes were observed at the moraine and talus sites, while a more dynamic pattern was recorded at the rock wall site. Here, a higher interannual variability in the number of freeze–thaw days was also detected, which showed evidence of the important role of the snow cover as a ground surface insulator in the area. Seasonal frost conditions are widespread today in the high lands of the massif. No permafrost regime was detected in the area, though mean temperatures measured at 0.5 m depth at the Forcadona buried ice patch during 2006–07 (0.1 °C) suggest that permanent negative values may be reached at deeper layersinfo:eu-repo/semantics/publishedVersio

Sedimentological characteristics of ice-wedge polygon terrain in Adventdalen (Svalbard): environmental and climatic implications for the late Holocene

Ice wedges are widespread periglacial features in the landscape of Adventdalen, Svalbard. The networks of ice wedges have created areas with well-developed polygonal terrains in the lowest fluvial terraces in this valley. We have examined the sedimentological characteristics of the northern and southern banks of the Advent river for palaeoenvironmental purposes. The base of two sedimentary sections reported radiocarbon dates of 3.3 and 3.9 ka BP, respectively. The northern site is constituted by three very different lithostratigraphical units, which suggests that their formation should be related to different environmental and climate conditions. By contrast, the southern section shows a rather homogeneous composition, with no significant variations in grain size and organic matter content. In both cases the uppermost sediments are constituted by a thick aeolian deposit. According to our data, warmer climate conditions may have prevailed during the mid Holocene until 3.3 ka BP with widespread peat formation in the valley bottom. Subsequently, a period with alternating soil formation and aeolian sedimentation took place from 3 to 2.5 ka BP, probably due to increasing climatic severity. During the last millennium a long-term cooling trend has favoured aeolian deposition in the lowest part of Adventdalen.info:eu-repo/semantics/publishedVersio