Conference Presentations by Hernan Sala
SCAR XXXI & Open Science Conference, 2010, Buenos Aires. 4th. Open Science Conference CD-ROM. Abstract n. 674, 1 pp.
Significant increases in surface temperatures associated with recurrent glaciological changes obs... more Significant increases in surface temperatures associated with recurrent glaciological changes observed in the Antarctic Peninsula (AP) during the last decades are well documented in bibliography. However, the availability of data on the Southwestern region of the AP has always been very limited. In order to gather the scarce available data about near surface temperature at this region, different data sources were consulted. Conventional weather stations San Martín (SM) and Rothera, and automatic weather stations (AWS), Dismal and Kirkwood, were considered for the Antarctic summer periods 2001-2009. In the case of SM the analysis could be extended until 1979. Air temperature areal averages were also obtained for an area included in Margarite Bay from two reanalysis provided by the National Centers for Environmental Prediction/Nacional Center for Atmospheric Research (NCEP/NCAR). Monthly correlations from daily air temperature anomalies between the mentioned data sources were obtained. Data from reanalysis showed poor correlations and were left out of further analysis. Given that the most important glaciological changes occur during the summer season, only December, January and February were the months considered. Significant positive temperature trends for SM were found along the period 1980- 2009. These changes are also reflected in Positive Degree Day (PDD) and Melt Day (MD), having increased 24ºC and 5.9 days per decade, respectively. In order to complete the gaps present in AWS and Rothera data series, a linear model obtained from scatterplots established between the series, which obtained best correlations, was applied. PDD and MD were analyzed for the reconstituted temperature series.
Memorias del V Simposio Latinoamericano sobre Investigaciones Antárticas y II Simposio Ecuatoriano de Ciencia Polar, La Libertad - Salinas - Guayaquil, Ecuador, Ago. 28 - Sept. 4 / 2009, 2009
El presente estudio comprende las zonas periglaciales de la isla James Ross y Vega, al noreste de... more El presente estudio comprende las zonas periglaciales de la isla James Ross y Vega, al noreste de la península Antártica. Allí se observa la formación de permafrost rico en hielo, principalmente en las morenas laterales de los glaciares. El calentamiento climático, que afecta de manera notable a la península Antártica, produjo cambios en la morfología del permafrost, incluyendo el desarrollo de termokarst. Este proceso origina subsidencia en el terreno por fusión de hielo y el deslizamiento gradual de material clástico en las laderas circundantes. La dinámica de la formación y evolución de estos lagos indica el desequilibrio climático asociado con la alteración de permafrost de alto contenido de hielos subterráneos.
Memorias del V Simposio Latinoamericano sobre Investigaciones Antárticas y II Simposio Ecuatoriano de Ciencia Polar, La Libertad - Salinas - Guayaquil, Ecuador, Ago. 28 - Sept. 4 / 2009, 2009
La planicie Lago Monolito está ubicada en el extremo norte de la isla James Ross, frente a la pen... more La planicie Lago Monolito está ubicada en el extremo norte de la isla James Ross, frente a la península antártica. Abarca un sector de aproximadamente 40 km, comprendido entre el punto más alto de las mesetas volcánicas (400 y 600 m.s.n.m.), en las márgenes de los glaciares “Whisky” y Lachman, y la costa del mar. La presencia del permafrost ha sido determinada a través de mediciones de temperatura en la capa activa y en el techo del permafrost. También se realizaron observaciones directas de los afloramientos y depósitos, y sondeos eléctricos verticales (SEV). Estos estudios fueron llevados a cabo en diferentes lugares clave del ambiente criogénico.
Data of the Western Antarctic Peninsula (WAP) ice fields remains little until today, although thi... more Data of the Western Antarctic Peninsula (WAP) ice fields remains little until today, although this region represents a key area of rapid on going climate change. Within the past 50 years arise in average annual air temperature of 2.5°C has been reported for the region (Cook et al., 2005). Melting processes represent an important component of mass loss from the polar ice sheets. The understanding and quantification of these processes is crucial to predict future cryospheric response to climate forcing, and consequent sea level raise. Changes of the glacial run off system have direct impact on the coastal ecosystems, due to altering freshwater and sediment transport.
EMS Annual Meeting Abstracts, 2016
The South Shetland Islands are located at the northern tip of the Antarctic Peninsula (AP) which ... more The South Shetland Islands are located at the northern tip of the Antarctic Peninsula (AP) which is among the fastest warming regions on Earth. Surface air temperature increases (∼3 K in 50 years) are concurrent with retreating glacier fronts, an increase in melt areas, ice surface lowering and rapid break-up and disintegration of ice shelves. Observed surface air temperature lapse rates show a high variability during winter months (standard deviations up to ±1.0 K/100 m), and a distinct spatial variability reflecting the impact of synoptic weather patterns especially during winter glacial mass accumulation periods. The increased mesocyclonic activity during the winter time in the study area results in intensified advection of warm, moist air with high temperatures and rain, and leads to melt conditions on the ice cap, fixating surface air temperatures to the melting point. Five years of glaciological measurements on mass balance stake transects are used with a glacier melt model to assess changes in melt water input to the coastal waters, glacier surface mass balance and the equilibrium line altitude. Glaciological measurements and literature review suggest a change of more than 150m in 15 yr's. Analysis of area changes in accumulation zone to the total glacier area are used to define a tipping point where the negative trends in glacier mass balance is becoming irreversible.
4th SCAR Open Science Conference - Antarctica: Witness to the Past and Guide to the Future. S. Marenssi (editor)., 2010
Coastal geomorphologic processes were studied in two areas of northern Marambio (Seymour) Island:... more Coastal geomorphologic processes were studied in two areas of northern Marambio (Seymour) Island: Oviedo (Larsen) Cove and Lopez de Bertodano Bay. In the first one, morphological changes were analyzed by aerial photographs from 1978 and 2010, denoting during this period the complete erosion of a spit. Furthermore, in the surroundings of Vallverdú Boat House, located in Lopez de Bertodano Bay, topographic measurements were made to characterize coastal morphodynamics using a Total Station. This sector presents an active cliff retreat associated mainly to destructive cryogenic processes related to the climate change. Main factors that condition mass-wasting are intense friability and jointing of sedimentary rocks that compose the cliff. Trigger factors are erosive action of waves and water from snow melting and summer free aquifer outcropping. Also associated with thermal erosion, rills and gullies were observed in the two sectors studied, affecting the active layer and permafrost table. In Oviedo Cove this process disturbs a fluvio-marine terrace (syngenetic permafrost), while in the Lopez de Bertodano Bay modifies the outcrops of La Meseta Formation (epigenetic permafrost).
Octave es un potente lenguaje de programación científica de libre distribución orientado al cálcu... more Octave es un potente lenguaje de programación científica de libre distribución orientado al cálculo numérico; pero su capacidad para elaborar mapas es bastante desconocida. Aquí se brindan ejemplos de mapas elaborados a partir de una serie de funciones disponibles en Internet. La ventaja de generar mapas en Octave consiste en lograr una continuidad entre la etapa de análisis de datos y su correspondiente mapeo. Para ello son necesarios conocimientos básicos de programación, ya que los mapas no se obtienen de manera tan intuitiva como en un SIG. Sería de gran ayuda contar con nuevas funciones que complementen u optimicen los pocos paquetes existentes orientados al mapeo. Se observa que la potencialidad de Octave para producir mapas está subexplotada. Se recomienda a los interesados explorar las distintas funciones que ofrecen M_map, Mapping y otros paquetes.
Die nationale Mission TanDEM-X besteht aus zwei nahezu baugleichen SAR Instrumenten die durch ihr... more Die nationale Mission TanDEM-X besteht aus zwei nahezu baugleichen SAR Instrumenten die durch ihren Formationsflug seit 2010 die Möglichkeit zur Erzeugung von digitalen Geländemodellen aus bi-statischen SAR-Daten ermöglichen. Durch die zeitgleiche Aufnahme der beiden Szenen wird ähnliche der SRTM-Mission eine zeitliche Dekorrelation des SAR-Signals weitestgehend vermieden. Bisherige Geländemodelle der Antarktischen Halbinsel sind meist auf heterogenen Datenbeständen aufgebaut und hierdurch stark bzgl. Konsistenz, Genauigkeit und Nutzbarkeit eingeschränkt. Im Rahmen einer Masterarbeit wurde ein digitales Geländemodell von King George Island erstellt. Gut 90% der Insel sind eisbedeckt. Die Prozessierung nutzt differentielle Interferometrie unter Einsatz eines Referenzgeländemodells. Hierdurch den differentiellen Ansatz wird beim Phase-unwrapping Prozess eine geringere Fehleranfälligkeit bzgl. Phasensprüngen erzielt. Für eine komplette Abdeckung der Insel werden mehrere Szenen benötigt, die zu einem Mosaik zusammengesetzt werden müssen. Dies wird durch eine Anpassung in den Überlappungsbereichen erzielt. Zur absoluten Referenzierung sowie zur unabhängigen Validierung wurden differentielle GPS-Messungen aus Feldkampagnen eingesetzt. Diese umfassen Messungen auf festem Untergrund wie auf Schnee-und Eisoberflächen. Die Ergebnisse zeigen eine gute Übereinstimmung zwischen Feldmessungen und TanDEM-X Geländemodell. Um die Frage der Eindringtiefe des X-Band Signals in Schnee und Eis zu adressieren werden TanDEM-X Aufnahmen aus dem antarktischen Sommer und Winter verglichen.
Skvarca P, Sala H, Rau F and Ermolin E. Drastic changes in cryosphere of northeastern Antarctic Peninsula induced by climatic warming. Proceedings of the 1st CliC Int. Science Conference, 11-15 April 2005, Beijing, China. WCRP-125 (DVD), WMO/TD No. 1300, October 2006, 2005
Effect of increased glacier melt on diagenetic Fe cycling in marine sediments at King George Island (Antarctica). Henkel S, Kasten S, Sala H, Busso A & Staubwasser M (2013) Mineralogical Magazine, 77(5) 1287, 2013
The glacier melt of the Western Antarctic Peninsula and its surrounding islands influences biogeo... more The glacier melt of the Western Antarctic Peninsula and its surrounding islands influences biogeochemical processes in the water column and the marine sediment by changing the flux of mineral particles and nutrients (e.g. Fe) into the ocean. Sediment and pore water samples were collected at King George / 25 de Mayo Island (South Shetland Islands) to unravel how the vicinity of ice-covered and-uncovered terrestrial environment affects redox zonation and diagenetic processes in the coastal sediments. The post-depositional dissolution of Fe-minerals and the stable Fe isotope signatures of pore water and specific Fe minerals were of special interest since changing Fe supplies-as reactive particles via melting icebergs or meltwater streams or dissolved via diffusion from the sediment into the bottom water-might not only impact local biogeochemical cycles but most likely also impact productivity in the Southern Ocean. Sediment cores of up to 45 cm length were retrieved in Potter Cove, Marian Cove, and Maxwell Bay. In vicinity to the glaciers the sediments showed an extended redox zonation. The post-oxic zone with Fe 2+ concentrations of up to 300 µM ranged from 1 to 25 cm depth. Most probably, microbial activity in sediments close to the glaciers is sluggish due to low input of organic matter (OM). More condensed redox zones prevailed in troughs where OM from terrestrial or marine sources accumulates and in vicinity to research stations. The upward directed diffusive Fe 2+ fluxes as inferred from pore water profiles range between 0 and ~1050 µM m-2 d-1. However, the correlation to the intensity of diagenesis is not straightforward. Fe isotopes of specific minerals were used to assess the intensity of Fe cycling. With ongoing Fe-oxide dissolution, the residual Fe pool becomes enriched in 56 Fe, whereas dissolved Fe and secondary Fe-oxides become enriched in 54 Fe. Thus, easily reducible Fe oxides show lowest ! 56 Fe values at the top of the sediment column. We suggest that the retreat of the glaciers indirectly results in higher OM fluxes to shelf areas fueling diagenetic processes/nutrient recycling.
3ª Conferencia Internacional de Software Libre CISL2012. Biblioteca Nacional, CABA, 15-17 de octubre de 2012., Oct 17, 2012
Herramientas de Software Libre para el análisis de datos científicos. Breve sinopsis y ejemplos a... more Herramientas de Software Libre para el análisis de datos científicos. Breve sinopsis y ejemplos aplicados al estudio del Sector Antártico Argentino Núñez Pölcher, Pablo; Sala, Hernán; Matko, Claudio 1 de agosto de 2012
Los modelos digitales o numéricos son, en esencia, una representación simplificada de la realidad... more Los modelos digitales o numéricos son, en esencia, una representación simplificada de la realidad que procura reflejar alguna o varias de sus propiedades. Se pueden entender como una simplificación, debido a la necesidad de reducir la complejidad del objeto real, y además, debido al desconocimiento o a la incertidumbre en algunas de sus propiedades. Por lo tanto, un Modelo Digital del Terreno (MDT) es una simplificación de la topografía y morfología real, que se sustenta en una estructura numérica, resultado del análisis estadístico de la información del terreno.
European Geosciences Union (EGU), General Assembly 2012. Vienna, Austria, 22 – 27 April 2012
The Antarctic Peninsula is amongst the fastest warming places on Earth and further temperature in... more The Antarctic Peninsula is amongst the fastest warming places on Earth and further temperature increase is to be expected. It has undergone rapid environmental changes in the past decades. Exceptional rates of surface air temperature increases (2.5K in 50 years) are concurrent with retreating glacier fronts, an increase in melt areas, surface lowering and rapid retreat, break-up and disintegration of ice shelves. The South Shetland Islands are located on the northern tip of the Antarctic Peninsula and are especially vulnerable to climate change due to their maritime climate. For King George (25 de Mayo) Island we have compiled a unique data set comprising direct measurements of evaporation and sensible heat flux by eddy covariance on the Warszawa Icefield for the austral summers November 2010 to March 2011 and January to February 2012 in combination with a fully equipped automated weather station measuring long-and shortwave radiation components, profiles of temperature, humidity and wind velocities as well as glacier ice temperatures in profile. The combination with the eddy covariance data allows for analysis of variability and seasonality of surface energy balance components on a glacier for an entire year. Repeat measurements of surface lowering at different locations on King George Island are used for analysis of multi-sensor satellite data to identify melt patterns and bare ice areas during summer. In combination with long-term time series of weather data, these data give indication of the sensitivity of the inland ice cap to the ongoing changes. This research is part of the ESF project IMCOAST funded by BMBF. Field work was carried out at the Dallmann laboratory (Carlini, King George / 25 de Mayo Island) in cooperation with the Instituto Antartico Argentino (Argentina) and the Alfred Wegener Institute (Germany).
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Conference Presentations by Hernan Sala