165 research outputs found

    Los glaciares de Islandia

    Get PDF

    Global maps of soil temperature

    Get PDF
    Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

    Jökulhlaups: riadas glaciares en Islandia

    Get PDF

    Geomorfología glaciar del flanco noroeste del volcán Hectes Tholus, Marte

    Get PDF
    Tesis Doctoral de la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, Departamento de Geodinámica, leída el 05-11-2015El volcán Hecates Tholus (32.18°N, 150.28ºE; cuadrante MC-7), de unos 180 km de diámetro y 5.300 metros de altura, es el único edificio de la provincia volcánica de Elysium, en las Tierras Bajas de Marte, en el que se han descrito rasgos geomorfológicos que podrían estar causados por procesos glaciares. Además, distintos autores relacionan la red radial de canales que surcan las laderas del volcán como causadas por la fusión de un antiguo casquete glaciar en la cima del edificio, siendo éste un ejemplo más de las intensas interacciones magma-agua en esta región del planeta, cercana al antiguo océano marciano y que dieron lugar a fenómenos muy interesantes, como los terrenos caóticos de Galaxias Chaos, a pocos kilómetros del volcán. Una característica muy particular de este edificio volcánico es la presencia de dos depresiones anidadas en la base de la ladera Noroeste, de 20 y 60 km de diámetro. La menor de ellas (Depresión A), situada a mayor altitud, ha sido interpretada por algunos autores como causada por una erupción lateral del volcán hace unos 350 Ma. Sin embargo, la de mayor diámetro y situada a menor altitud (Depresión B), no tiene un origen claro, aunque se han discutido distintas hipótesis. En cualquier caso, es especialmente en el interior de estas depresiones donde se han encontrado los rasgos geomorfológicos que podrían estar causados por actividad glacial, como posibles cordones morrénicos y depósitos de till...Hecates Tholus volcano (32.18°N, 150.28ºE; MC-7 quadrangle) is the only edifice of the Elysium volcanic province, at the lowlands of Mars, showing evidence of glacial activity, as deduced from the geomorphological study. This work completes the previous regional works with the aim of refine our knowledge about the glacial events occurred at this site of Mars. We build a detailed geomorphological mapping (1:100.000 in scale) of the lower NW flank of the edifice (31.8º-33.08ºN, 148.37º-149.38ºE), where the glacial ”marsforms” concentrate, based on the use of CTX images. Moreover, we performed detailed crater size-frequency distribution, geomorphological, morphometric, compositional, and thermal analysis to finish the cartography and get the necessary evidences to model the glacial evolution of the area. Those analyses were possible thanks to the use of a wide variety of images, including HRSC, HiRISE, MOC, and THEMIS, as well as HRSC-derived topographic data, THEMIS-derived Brightness surface temperature, TES-derived thermal inertia maps, and SHARAD ground penetration radargrams, everything integrated into a Geographic Information System...Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEunpu

    Thermal isostasy on Mars

    Get PDF
    Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

    Evidence of gully formation by regional groundwater flow in the Gorgonum–Newton region (Mars)

    Get PDF
    The discovery of gullies on Mars suggests liquid water activity near the surface of the planet in recent times. Since liquid water is unstable under the present-day P–T martian conditions, the formation mechanisms of the gullies, and the source of the putative water, have been a matter of debate for the last years. To provide new insights into these matters, we have approached the problem studying the gullies in relation to their regional setting. A major point in our study relates to the geographic orientation of gullies, an aspect that has been previously regarded as a crucial matter in different models, and has profound implications regarding their origin. We present a comprehensive and detailed survey of the Gorgonum–Newton region, and a study of the Dao and Nirgal Vallis regions. The survey was carried out with the aid of 965 high-resolution MOC images (752 for Gorgonum–Newton, 102 for Nirgal Vallis and 111 for Dao Vallis regions), and MOLA-derived DEMs.We found that gullies display a clear regional pattern, geographically and topographically consistent with a decreasing regional slope. We interpret the results in terms of the existence of several groundwater flow systems operating at different scales, which ultimately may have led to gully formation by seepage at the slopes of craters and canyons. We suggest that aquifers discharging at gully systems may have recharged from the surface, in response to the melting of young partially eroded ice-rich deposits

    Recent shallowing of the thaw depth at Crater Lake, Deception Island, Antarctica (2006-2014)

    Get PDF
    The Western Antarctic Peninsula region is one of the hot spots of climate change and one of the most ecologically sensitive regions of Antarctica, where permafrost is near its climatic limits. The research was conducted in Deception Island, an active stratovolcano in the South Shetlands archipelago off the northern tip of the Antarctic Peninsula. The climate is polar oceanic, with high precipitation and mean annual air temperatures (MAAT) close to -3°C. The soils are composed by ashes and pyroclasts with high porosity and high water content, with ice-rich permafrost at -0.8°C at the depth of zero annual amplitude, with an active layer of about 30 cm. Results from thaw depth, ground temperature and snow cover monitoring at the Crater Lake CALM-S site over the period 2006 to 2014 are analyzed. Thaw depth (TD) was measured by mechanical probing once per year in the end of January or early February in a 100 × 100 m with a 10 m spacing grid. The results show a trend for decreasing thaw depth from ci. 36 cm in 2006 to 23 cm in 2014, while MAAT, as well as ground temperatures at the base of the active layer, remained stable. However, the duration of the snow cover at the CALM-S site, measured through the Snow Pack Factor (SF) showed an increase from 2006 to 2014, especially with longer lasting snow cover in the spring and early summer. The negative correlation between SF and the thaw depth supports the significance of the influence of the increasing snow cover in thaw depth, even with no trend in the MAAT. The lack of observed ground cooling in the base of the active layer is probably linked to the high ice/water content at the transient layer. The pyroclastic soils of Deception Island, with high porosity, are key to the shallow active layer depths, when compared to other sites in the Western Antarctic Peninsula (WAP).Ministerio de Economía y Competitivida

    Stepwise transversus abdominis muscle release for the treatment of complex bilateral subcostal incisional hernias.

    Get PDF
    Background Management of subcostal incisional hernias is particularly complicated due to their proximity to the costochondral limits in addition to the lack of aponeurosis on the lateral side of the abdomen. We present our results of posterior component separation through the same previous incision as a safe and reproducible technique for these complex cases. Methods We present a multicenter and prospective cohort of patients diagnosed with bilateral subcostal incisional hernias on either clinical examination or imaging based on computed tomography from 2014 to 2020. The aim of this investigation was to assess the outcomes of abdominal wall reconstruction for subcostal incisional hernias through a new approach. The outcomes reported were short- and long-term complications, including recurrence, pain, and bulging. Quality of life was assessed with the European Registry for Abdominal Wall Hernias Quality of Life score. Results A total of 46 patients were identified. All patients underwent posterior component separation. Surgical site occurrences occurred in 10 patients (22%), with only 7 patients (15%) requiring procedural intervention. During a mean follow-up of 18 (range, 6–62), 1 (2%) case of clinical recurrence was registered. In addition, there were 8 (17%) patients with asymptomatic but visible bulging. The European Registry for Abdominal Wall Hernias Quality of Life score showed a statistically significant decrease in the 3 domains (pain, restriction, and cosmetic) of the postoperative compared with the preoperative scores. Conclusion Posterior component separation technique for the repair of subcostal incisional hernias through the same incision is a safe procedure that avoids injury to the linea alba. It is associated with acceptable morbidity, low recurrence rate, and improvement in patients’ reported outcomes.pre-print371 K
    corecore