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Colección de artículos en temáticas antárticas publicados por investigadores de la Universidad de Magallanes en diferentes fuentes, acorde a las políticas del editor.
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Browsing Artículos by Author "Añel, Juan A."
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Item Assessing the impact of retreat mechanisms in a simple antarctic ice sheet model using bayesian calibration(Public Library of Science, 2017-01-12) Ruckert, Kelsey L.; Shaffer, Gary; Pollard, David; Guan, Yaguen; Wong, Tony E.; Forest, Chris E.; Keller, Klaus; Añel, Juan A.The response of the Antarctic ice sheet (AIS) to changing climate forcings is an important driver of sea-level changes. Anthropogenic climate change may drive a sizeable AIS tipping point response with subsequent increases in coastal flooding risks. Many studies analyzing flood risks use simple models to project the future responses of AIS and its sea-level contributions. These analyses have provided important new insights, but they are often silent on the effects of potentially important processes such as Marine Ice Sheet Instability (MISI) or Marine Ice Cliff Instability (MICI). These approximations can be well justified and result in more parsimonious and transparent model structures. This raises the question of how this approximation impacts hindcasts and projections. Here, we calibrate a previously published and relatively simple AIS model, which neglects the effects of MICI and regional characteristics, using a combination of observational constraints and a Bayesian inversion method. Specifically, we approximate the effects of missing MICI by comparing our results to those from expert assessments with more realistic models and quantify the bias during the last interglacial when MICI may have been triggered. Our results suggest that the model can approximate the process of MISI and reproduce the projected median melt from some previous expert assessments in the year 2100. Yet, our mean hindcast is roughly 3/4 of the observed data during the last interglacial period and our mean projection is roughly 1/6 and 1/10 of the mean from a model accounting for MICI in the year 2100. These results suggest that missing MICI and/or regional characteristics can lead to a low-bias during warming period AIS melting and hence a potential low-bias in projected sea levels and flood risks.Item UV irradiance and albedo at Union Glacier Camp (Antarctica): a case study(Public Library of Science (PLOS), 2014) Cordero, Raúl R.; Damiani, Alessandro; Ferrer, Jorge; Jorquera, José; Tobar, Mario; Labbe, Fernando; Carrasco, Jorge; Laroze, David; Añel, Juan A.We report on the first spectral measurements of ultraviolet (UV) irradiance and the albedo at a Camp located in the southern Ellsworth Mountains on the broad expanse of Union Glacier (700 m altitude, 79u 469 S; 82u 529W); about 1,000 km from the South Pole. The measurements were carried out by using a double monochromator-based spectroradiometer during a campaign (in December 2012) meant to weight up the effect of the local albedo on the UV irradiance. We found that the albedo measured at noon was about 0.95 in the UV and the visible part of the spectrum. This high surface reflectivity led to enhancements in the UV index under cloudless conditions of about 50% in comparison with snow free surfaces. Spectral measurements carried out elsewhere as well as estimates retrieved from the Ozone Monitoring Instrument (OMI) were used for further comparisons.