Hernan Sala

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Meteorological measurements from the Fourcade and Polar Club Glacier, Warszawa Icefield, King George Island, West Antarctica

The South Shetland Islands are located at the northern tip of the AP which is among the fastest w... more The South Shetland Islands are located at the northern tip of the AP which is among the fastest warming regions on Earth. The islands are especially vulnerable to climate change due to their exposure to transient low-pressure systems and their maritime climate. Surface air temperature increases (2.5K 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. We have compiled a unique meteorological data set for the King George Island (KGI)/Isla 25 de Mayo, the largest of the South Shetland Islands. It comprises high-temporal resolution and spatially distributed observations of surface air temperature, wind directions and wind velocities, as well as glacier ice temperatures in profile with a fully equipped automatic weather station on the Warszawa Icefield, from November 2010 and ongoing. In combination with two long-term synoptic datasets (40 and 10 years, respectively) and NCEP/NCAR reanalysis data, we have looked at changes in the climatological drivers of the glacial melt processes, and the sensitivity of the inland ice cap with regard to winter melting periods and pressure anomalies. The analysis has revealed' a positive trend of 5K over four decades in minimum surface air temperatures for winter months, clearly exceeding the published annual mean statistics, associated to a decrease in mean monthly winter sea level pressure. This concurs with a positive trend in the Southern Annular Mode (SAM) index, which gives a measure for the strength and extension of the Antarctic vortex. We connect this trend with a higher frequency of low-pressure systems hitting the South Shetland Islands during austral winter, bringing warm and moist air masses from lower latitudes. Due to its exposure to the impact of transient synoptic weather systems, the ice cap of KGI is especially vulnerable to changes during winter glacial mass accumulation period. A revision of seasonal changes in adiabatic air temperature lapse rates and t [...]

Software Libre y Acceso Abierto: dos formas de transferencia de tecnología

Revista Iberoamericana de Ciencia, Tecnología y Sociedad - CTS, Jan 5, 2014

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Breve ensayo sobre educación, empleo y sociedad en el contexto de la pandemia de Covid-19

Origen, consolidación, expansión e implicancias del Acceso Abierto (Open Access) en América Latina y el Caribe

Revista educación superior y sociedad, Jun 20, 2012

En este trabajo se realizo una sintesis de las ideas previas que posibilitaron el origen del Acce... more En este trabajo se realizo una sintesis de las ideas previas que posibilitaron el origen del Acceso Abierto (AA) y que permitieron su consolidacion y expansion, en particular, en America Latina y el Caribe. Se analizaron las principales declaraciones relativas al AA: la Iniciativa de Budapest, la declaracion de Bethesda y la de Berlin, el Compromiso de Tunez, el Comunicado Final de la reunion de Politicas de Ciencia y Tecnologia para el Siglo XXI de la Organizacion para la Cooperacion y el Desarrollo Economico y las declaraciones de Salvador y de Mar del Plata. Se realizo una sinopsis de diferentes recursos que coadyuvan al desarrollo del AA en la region. Entre ellos las licencias Creative Commons, de Documentacion GNU, el copyleft y algunas de sus implicancias. Tambien se consideraron las bibliotecas y repositorios electronicos mas difundidos en la region: la Red SciELO (Scientific Electronic Library Online), la Red de Bibliotecas Virtuales de Ciencias Sociales de America Latina y el Caribe del Consejo Latinoamericano de Ciencias Sociales, entre otras; ademas, se realizo una breve descripcion cuantitativa del crecimiento de SciELO. Luego, se discutieron los beneficios que resultan de la aplicacion del AA en Educacion Superior y sus limitaciones. Por otra parte, se resalto la importancia de extrapolar el AA a todos los contenidos relativos a la Educacion Superior. Finalmente, se realizo un analisis critico del AA considerandolo en el marco mas amplio de la inclusion digital y haciendo hincapie en la apropiacion social de las tecnologias de la informacion y la comunicacion.

Eisen im Südozean – aktuelle Forschung im Hinblick auf das Abschmelzen der Gletscher der Westantarktischen Halbinsel

Kinematic measurements on shoreline Refugio Elefante to Lighthouse Potter Cove, King Georg Island, Antarctica

Differential GPS (DGPS) stationary and kinematic measurements on King Georg Island, Antarctica

During the summer field campaigns within the period November 2010 to March 2013, intensive repeat... more During the summer field campaigns within the period November 2010 to March 2013, intensive repeat measurements with Differential GPS (DGPS) at static points of the mass balance stakes as well as kinematic tracks along a grid covering Fourcade and Polar Club glaciers on the Potter Peninsula and the Bellinghausen Dome on the Fieldes Peninsula were carried out. Data was gridded and interpolated to come up with a more exact topography (digital elevation model) for the area of investigation.Data was used to assess glacier velocities. Kinematic tracks were gridded and interpolated to come up with a more exact topography (digital elevation model) for the area of investigation. The data also serves as ground truthing for georeferencing of satellite imagery data by providing exact position coordinates of distinct land marks.

Kinematic measurements on Yamana inner perimeter, King Georg Island, Antarctica

Análisis y Comparación De Dos Modelos Digitales De Elevación en La Isla 25 De Mayo (King George Island), Islas Shetland Del Sur, Antártida Analysis and Comparison of Two Digital Elevation Models in the 25 De Mayo Island (King George Island), Shetland Del Sur Islands, Antarctica

En este trabajo se analizan y compararan los dos únicos Modelos Digitales de Elevación (MDE) elab... more En este trabajo se analizan y compararan los dos únicos Modelos Digitales de Elevación (MDE) elaborados de manera independiente y de acceso público, que existen al presente, para el área de la Isla 25 de Mayo/King George Island (I25M), Islas Shetland del Sur, Antártida. Uno de ellos, el Radarsat Antarctic Mapping Project Digital Elevation Model Version 2 (RAMPv2) cubre exclusivamente la Antártida, mientras que el otro, el Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model Version 2 (GDEMv2), es de alcance cuasi-global. Para comparar ambos modelos se tuvieron en cuenta, entre otras variables, la resolución espacial, la escala de trabajo, los rangos y las diferencias de elevaciones. El objetivo final consistió en determinar cuál de los dos MDE representa con mayor fidelidad la topografía de la I25M y, en consecuencia, resulta más apropiado para la generación de nuevos productos digitales derivados. Los resultados de los análisis indican que, a pesar de tener menor resolución espacial (200 m), el modelo RAMPv2 es el más adecuado de los dos. Esta selección se fundamenta sobre la base de que el modelo RAMPv2 posee mayor coherencia en cuanto a las características topográficas y morfológicas de la isla, no presenta valores aberrantes y posee una diferencia de ~40 m con respecto a la cota máxima de la isla, según indican otras fuentes independientes. Por último, se proponen algunas sugerencias con respecto a la generación y futura disponibilidad de MDE para la I25M.

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Surface energy balance and turbulence measurements on Warszawa Icefield, King George Island, West Antarctica

AGUFM, Dec 1, 2012

Surface energy balance measurements and modeling on the ice cap of King George Island, West Antarctica

EGU General Assembly Conference Abstracts, Apr 1, 2012

ABSTRACT The Antarctic Peninsula is amongst the fastest warming places on Earth and further tempe... more ABSTRACT 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 Peninsula and are especially vulnerable to climate change due to their maritime climate. For King George 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 short-wave 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 (Jubany, King George Island) in cooperation of the Instituto Antartico Argentino (Argentina) and the Alfred-Wegener Institute (German).

Winter melt conditions of the inland ice cap on King George Island, Antarctic Peninsula

Erdkunde, Dec 24, 2015

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. We have compiled a unique meteorological dataset for the King George Island (KGI)/Isla 25 de Mayo, the largest of the South Shetland Islands. It comprises high-temporal resolution and spatially distributed observations of surface air temperature, wind directions and wind velocities, glacier ice temperatures in profile with a fully equipped automatic weather station as well as snow accumulation and ablation measurements on the Warszawa Icefield, since November 2010 and ongoing. In combination with long-term synoptic datasets (40 and 10 years, respectively) and atmospheric circulation indices datasets, we have looked at changes in the climatological drivers of the glacial melt processes, and the sensitivity of the inland ice cap with regard to winter melting periods and pressure anomalies. The analysis has revealed a positive trend of 5 K over four decades in minimum surface air temperatures for winter months, clearly exceeding the published annual mean statistics, associated to a negative trend in mean monthly winter sea level pressure. This concurs with a positive trend in the Southern Annular Mode (SAM) index, which gives a measure for the strength and extension of the Antarctic vortex. We connect this trend with a higher frequency of low-pressure systems hitting the South Shetland Islands during austral winter, bringing warm and moist air masses from lower latitudes. A revision of spatial and seasonal changes in adiabatic air temperature lapse rates reveals the high sensitivity of the upper ice cap to free atmospheric flow and synoptic changes. 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. This paper assesses the impact of long-term change in large-scale atmospheric circulation and variability and climatic changes on the atmospheric surface layer and glacier mass accumulation of the upper ice cap during winter season for the Warszawa Icefield on KGI. Supplementary data are available at http://dx.doi.org/10.1594/PANGAEA.848704 Zusammenfassung: Die Südshetland-Inseln befinden sich an der nördlichen Spitze der Antarktischen Halbinsel, welche weltweit zu den Regionen zählt, die am stärksten von der globalen Erwärmung betroffen sind. Beträchtliche Änderungen in der Umwelt sind die Konsequenz dieser Erwärmung. Außergewöhnliche Änderungsraten in der bodennahen Lufttemperatur (~3 K in 50 Jahren) gehen einher mit dem Rückzug von Gletscherfronten, der Zunahme von Gletscherschmelze, einem Absenken der Eisoberflächen und der Desintegration von Eisschelfen. Wir haben für die King George Insel/Isla 25 de Mayo (KGI), der größten der Südshetland Inseln, einen einzigartigen Datensatz zusammen getragen. Dieser beinhaltet zeitlich hochaufgelöste und räumliche Messungen von oberflächennaher Lufttemperatur, Windrichtungen und-geschwindigkeiten, Profile von Eistemperaturen mit einer voll ausgestatteten automatischen Wetterstation sowie Messungen von Schnee Akkumulation und Ablation auf dem Warschauer Eisfeld von November 2010 an und andauernd. In Verbindung mit langzeitlichen synoptischen Datensätzen (40 Jahre von 6-stündlichen Messungen) und Datensätzen von atmosphärischen Zirkulations-Indizes, untersuchen wir die klimatologischen Treiber für die Gletscherschmelze-Prozesse und die Vulnerabilität des Inland-Eisschildes mit Schwerpunkt auf den winterlichen Schmelzperioden und Luftdruck-Anomalien. Die Analyse zeigt einen positiven Trend von 5 K über 4 Dekaden in den Tagesminima der Lufttemperatur für die Wintermonate, welche die publizierten Trends der annualen Mittelwerte klar übersteigt, in Verbindung mit einem negativen Trend im monatlichen Mittel des barometrischen Luftdrucks auf Meeresniveau. Diese Änderungen gehen einher mit einem positiven Trend des Southern Annular Mode (SAM) Index, welcher ein Maß für die Stärke und die Ausdehnung des Antarktischen Vortex ist. Wir verbinden diese Beobachtungen mit einer höheren Frequenz von Tiefdruckgebieten, die im Süd-Winter auf die Südshetland-Inseln treffen und warme, feuchte Luftmassen aus den niedrigeren Breiten bringen. Durch seine Exposition ist die Eiskappe von KGI besonders empfindlich gegenüber Änderungen in der winterlichen Akkumulationsperiode von Gletschermassen. Eine Überprüfung der saisonalen und räumlichen Variabilität der Lufttemperaturgradienten zeigen Vol. 69 • No. 4 eine höhere Sensitivität des oberen Gletschers gegenüber Zirkulation der freien Atmosphäre und synoptischen Einflüssen insbesondere während der winterlichen Akkumulationsperiode von Gletschermassen. Oberflächennahe Lufttemperaturgradienten zeigen eine hohe Streuung in Wintermonaten (Standardabweichungen bis zu ±1.0 K/100 m) und eine ausgeprägte räumliche Variabilität, welche den Einfluss der synoptischen Wetterphänomene widerspiegelt. Die verstärkte zyklonische Aktivität im Forschungsgebiet in der Winterzeit resultiert in der Advektion feuchter, warmer Luft mit Regen und erhöhten Temperaturen in die Region, so dass sich regelmäßig winterliche Phasen mit Schmelzbedingungen einstellen. In dieser Publikation untersuchen wir den Einfluss von großskaligen und klimatischen Änderungen auf die bodennahe atmosphärische Grenzschicht und in Gletschermassen-Akkumulation des höher gelegenen Eisschildes während der Wintermonate. Die hier publizierten Daten sind verfügbar unter http://dx.

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Continuous meteorological observations at station ZAWS, Warszawa Icefield, King George Island, Antarctic Peninsula, 2012-01

Análisis y comparación de dos modelos digitales de elevación en la isla 25 de mayo (King George island), islas Shetland del sur, Antártida

Geoacta, Jun 25, 2014

En este trabajo se analizan y compararan los dos unicos Modelos Digitales de Elevacion (MDE) elab... more En este trabajo se analizan y compararan los dos unicos Modelos Digitales de Elevacion (MDE) elaborados de manera independiente y de acceso publico, que existen al presente, para el area de la Isla 25 de Mayo/King George Island (I25M), Islas Shetland del Sur, Antartida. Uno de ellos, el Radarsat Antarctic Mapping Project Digital Elevation Model Version 2 (RAMPv2) cubre exclusivamente la Antartida, mientras que el otro, el Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model Version 2 (GDEMv2), es de alcance cuasi-global. Para comparar ambos modelos se tuvieron en cuenta, entre otras variables, la resolucion espacial, la escala de trabajo, los rangos y las diferencias de elevaciones. El objetivo final consistio en determinar cual de los dos MDE representa con mayor fidelidad la topografia de la I25M y, en consecuencia, resulta mas apropiado para la generacion de nuevos productos digitales derivados. Los resultados de los analisis indican que, a pesar de tener menor resolucion espacial (200 m), el modelo RAMPv2 es el mas adecuado de los dos. Esta seleccion se fundamenta sobre la base de que el modelo RAMPv2 posee mayor coherencia en cuanto a las caracteristicas topograficas y morfologicas de la isla, no presenta valores aberrantes y posee una diferencia de ~40 m con respecto a la cota maxima de la isla, segun indican otras fuentes independientes. Por ultimo, se proponen algunas sugerencias con respecto a la generacion y futura disponibilidad de MDE para la I25M.

Breve ensayo sobre educación, empleo y sociedad en el contexto de la pandemia de Covid-19

Revista de Investigación y Disciplinas, Nov 1, 2021

Análisis y comparación de dos modelos digitales de elevación en la isla 25 de mayo (King George island), islas Shetland del sur, Antártida

Geoacta, 2014

Effect of increased glacier melt on diagenetic Fe cycling in marine sediments at King George Island (Antarctica)

Mineralogical Magazine, 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 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 Fe2+ 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 Fe2+ 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 56Fe, whereas dissolved Fe and secondary Fe-oxides become enriched in 54Fe. Thus, easily reducible Fe oxides show lowest !56Fe 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.

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Uso intensivo de herramientas de colaboración en línea en Educación Superior

Revista Electrónica de Didáctica en Educación Superior, 2013

Este artículo detalla una experiencia extracurricular de uso intensivo de herramientas de trabajo... more Este artículo detalla una experiencia extracurricular de uso intensivo de herramientas de trabajo grupal en línea, realizada por un grupo de docentes y alumnos del Instituto de Formación Técnica Superior Nº 22 de la Ciudad de Buenos Aires. Se la consideró no sólo como una actividad de aproximación a nuevas tecnologías, sino también como una experiencia grupal en la que se establecieron métodos y roles para el trabajo colaborativo. Palabras clave: Aprendizaje colaborativo - alfabetización digital - web 2.0 - tecnología educacional – Servicios educativos en la nube. An Online Collaborative Tools Experience in a Technical School Class This paper describes an experience of intensive online collaborative tools usage at a Technical School of Buenos Aires. The experienced was carried on by both teachers and students as an extra-curricular activity, and it was meant to be not only a first approach to specific technologies, but mainly a group experience in which common rules, methods and spe...

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Ice dynamics of Perito Moreno Glacier, southern Patagonia Icefield

Preprints of the Annual Conference, Japanese Society of Snow and Ice, 2005

Fotosíntesis: Una historia para pensar

En nuestra experiencia docente hemos encontrado que los alumnos tienen serias dificultades para c... more En nuestra experiencia docente hemos encontrado que los alumnos tienen serias dificultades para comprender las transformaciones que sufren la materia y la energía en los seres vivos; por esta razón, decidimos elaborar una encuesta que nos permita detectar el origen de las mismas y, en consecuencia, desarrollar una estrategia didáctica basada en el desarrollo histórico del concepto de fotosíntesis y los experimentos de J. B. Van Helmontz y J. Priestley, entre otros.

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