Línea de investigación:

Agua y extremos

Los eventos extremos tienen importantes efectos en la sociedad y existe una percepción generalizada del aumento en su recurrencia en todo el país. Los eventos recientes incluyen la megasequía en la zona central y sur (2010-2016), la peor floración de algas nocivas jamás registrada en Patagonia, la temporada de incendios sin precedentes de 2017 y grandes inundaciones y deslizamientos de tierra en el centro-norte de Chile (2015 y  2017).

Cuantificar, comprender y proyectar la ocurrencia de extremos climáticos es relevante dados sus efectos en los sistemas naturales versus los sistemas alterados. Los aumentos en la población y la expansión del uso del territorio aumentan nuestra exposición a eventos extremos, y existe una necesidad urgente de estudiar y apoyar a las comunidades para pasar de la vulnerabilidad a la resiliencia.

Para avanzar en esta línea de investigación, es imperativo cuantificar el papel de la variabilidad natural y las variaciones en eventos extremos basadas ​​en datos históricos y paleo-reconstrucción. Paralelamente, buscamos atribuir el aumento aparente en la ocurrencia de eventos extremos seleccionados en las últimas décadas al forzamiento climático antropogénico, utilizando técnicas de vanguardia. Por último, nuestro objetivo es estimar los posibles cambios en la frecuencia, intensidad y duración de los eventos extremos seleccionados durante el siglo XXI.

El área de ciencias sociales de nuestro grupo trabajará para comprender cómo la sociedad, desde las comunidades locales a las autoridades nacionales, se está adaptando a los cambios en eventos extremos, a través de la investigación centrada en las prácticas actuales, su utilidad, las barreras para la implementación y las oportunidades de mejora.








Noticias relacionadas a esta línea

Línea de InvestigaciónAñoAutoresTítuloRevistaFicha de PublicaciónDOIAbstractAccesoPáginasVolumenIndex
Agua y Extremos2017Cuchiara, G. C., Rappenglück, B., Rubio, M. A., Lissi, E., Gramsch, E., Garreaud, R. D.Modeling study of biomass burning plumes and their impact on urban air quality; a case study of Santiago de ChileAtmospheric EnvironmentVer ficha10.1016/j.atmosenv.2017.07.002On January 4, 2014, during the summer period in South America, an intense forest and dry pasture wildfire occurred nearby the city of Santiago de Chile. On that day the biomass-burning plume was transported by low-intensity winds towards the metropolitan area of Santiago and impacted the concentration of pollutants in this region. In this study, the Weather Research and Forecasting model coupled with Chemistry (WRF/Chem) is implemented to investigate the biomass-burning plume associated with these wildfires nearby Santiago, which impacted the ground-level ozone concentration and exacerbated Santiago's air quality. Meteorological variables simulated by WRF/Chem are compared against surface and radiosonde observations, and the results show that the model reproduces fairly well the observed wind speed, wind direction air temperature and relative humidity for the case studied. Based on an analysis of the transport of an inert tracer released over the locations, and at the time the wildfires were captured by the satellite-borne Moderate Resolution Imaging Spectroradiometer (MODIS), the model reproduced reasonably well the transport of biomass burning plume towards the city of Santiago de Chile within a time delay of two hours as observed in ceilometer data. A six day air quality simulation was performed: the first three days were used to validate the anthropogenic and biogenic emissions, and the last three days (during and after the wildfire event) to analyze the performance of WRF/Chem plume-rise model within FINNv1 fire emission estimations. The model presented a satisfactory performance on the first days of the simulation when contrasted against data from the well-established air quality network over the city of Santiago de Chile. These days represent the urban air quality base case for Santiago de Chile unimpacted by fire emissions. However, for the last three simulation days, which were impacted by the fire emissions, the statistical indices showed a decrease in the model performance. While the model showed a satisfactory evidence that wildfires plumes that originated in the vicinity of Santiago de Chile were transported towards the urban area and impacted the air quality, the model still underpredicted some pollutants substantially, likely due to misrepresentation of fire emission sources during those days. Potential uncertainties may include to the land use/land cover classifications and its characteristics, such as type and density of vegetation assigned to the region, where the fire spots are detected. The variability of the ecosystem type during the fire event might also play a role.http://linkinghub.elsevier.com/retrieve/pii/S135223101730443079-91vol.166Thomson Reuters ISI
Agua y Extremos, Cambio de Uso de Suelo2017Puchi, P., Muñoz, A. A., González, M. E., Abarzúa, A., Araya, K., Towner, R., Fitzek, R., Holz, A., Stahle, D.Potencial de los anillos de crecimiento de Pilgerodendron uviferum para el estudio histórico de las Iglesias de Chiloé, Patrimonio de la HumanidadBosque10.4067/S0717-92002017000100012Las iglesias de Chiloé son antiguas estructuras de madera reconocidas patrimonio de la humanidad por la UNESCO. Gran parte de su historia de construcción y reparaciones aún se desconoce. Considerando que muchas de las iglesias de Chiloé fueron construidas utilizando madera de Pilgerodendron uviferum, el objetivo de este trabajo fue evaluar el potencial de esta especie para datar piezas de madera de dos de estas históricas construcciones: las iglesias de Vilupulli e Ichuac. En Vilupulli se dataron piezas de 311 y 181 años provenientes de los pilares de la torre. Estas piezas fueron fechadas con cronologías de ancho de anillos de P. uviferum cercanas a las dos iglesias. También utilizando estas cronologías se dataron piezas de 79, 89, 97 y 135 años obtenidas a partir de los pilotes que sostienen el piso de la iglesia de Ichuac. Considerando que Vilupulli fue construida a principios del siglo XX, es posible que las muestras de la torre que presentaron fechas cercanas a 1918, sean parte del proceso tardío de construcción de la iglesia o de una restauración posterior. Por su parte, Ichuac fue construida a finales del siglo XIX, por lo que las piezas del piso que dataron entre 19201929, formarían parte de una posible restauración no descrita previamente en archivos históricos, la cual pudo ocurrir incluso varios años posterior a la fecha del anillo más reciente encontrado en las piezas estudiadas. Se concluye que P. uviferum tiene alto potencial para estudios históricos en estructuras patrimoniales en el sur de Chile.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-92002017000100012&lng=en&nrm=iso&tlng=en109-121vol.38Thomson Reuters ISI
Agua y Extremos; Cambio de Uso de Suelo2017Garreaud, R., Alvarez-Garreton, C., Barichivich, J., Boisier, J. P., Christie, D., Galleguillos, M., LeQuesne, C., McPhee, J., Zambrano-Bigiarini, M.The 2010-2015 mega drought in Central Chile: Impacts on regional hydroclimate and vegetationHydrology and Earth System Sciences Discussions10.5194/hess-2017-191Since 2010 an uninterrupted sequence of dry years, with annual rainfall deficits ranging from 25 to 45 %, has prevailed in Central Chile (western South America, 30–38° S). Although intense 1- or 2-year droughts are recurrent in this Mediterranean-like region, the ongoing event stands out because of its longevity and large spatial extent. The extraordinary character of the so-called Central Chile Mega Drought (MD) was established against century long historical records and a millennial tree-ring reconstruction of regional precipitation. The largest MD-averaged rainfall relative anomalies occurred in the northern, semi-arid sector of central Chile but the event was unprecedented to the south of 35° S. ENSO neutral conditions have prevailed since 2011 (but for the strong El Niño 2015) contrasting with La Niña conditions that often accompanied past droughts. The precipitation deficit diminished the Andean snowpack and resulted in amplified declines (up to 90 %) of river flow, reservoir volumes and groundwater levels along central Chile and westernmost Argentina. In some semiarid basins we also found a conspicuous decrease in the runoff-to-rainfall coefficient. A substantial decrease in vegetation productivity occurred in the shrubland-dominated, northern sector, but a mix of greening and browning patches occurred farther south where irrigated croplands and exotic forest plantations dominate. The ongoing warming in central Chile, making the MD one of the warmest 6-year period on record, may have also contributed to such complex vegetation changes by increasing potential evapotranspiration. The understanding of the nature and biophysical impacts of the MD contributes to preparedness efforts to face a dry, warm future regional climate scenario.https://www.hydrol-earth-syst-sci-discuss.net/hess-2017-191/1-37Thomson Reuters ISI
Agua y Extremos2017Borquéz González, RInterfaz ciencia-políticas públicas en Chile: una mirada a la investigación en cambio climáticoRevista Colombiana de Sociología10.15446/rcs.v40n2.66402En las últimas décadas, se han observado importantes cambios en torno a la relación entre la ciencia y la sociedad. Se ha transitado de un paradigma basado en que la ciencia está transformando la sociedad a otro que abre a la posibilidad de que la sociedad transforme la ciencia. El aporte de la esfera científica, al igual que el brindado por cada uno de los actores sociales, es fundamental para apoyar la toma de decisiones en política pública. Así lo ha demostrado el Panel Intergubernamental de Expertos sobre Cambio Climático (IPCC), que ha jugado un rol clave en la toma de acciones de la comunidad internacional. Sin embargo, la relación entre ciencia y política no ha sido suficientemente fluida en Chile. El objetivo del estudio fue identificar y analizar, a través de motodología cualitativa de carácter exploratorio, las brechas y los facilitadores de la relación entre investigadores del campo de las ciencias naturales y las políticas públicas en Chile, con énfasis en el área del cambio climático. Esto permitió analizar la estructura y la dinámica de incentivos a la actividad de las esferas científica y pública, y los mecanismos de comunicación y coordinaci;ón existentes entre ellas. Así, se identificaron ocho brechas y dos facilitadores. Resaltan el bajo interés de la esfera científica en realizar "asesorías" solicitadas por servicios públicos que generan poíticas públicas, la falta de incentivos o exigencias académicas para simplificar contenidos, así como la falta de comunicación y de interacción regular que generan una diferencia entre lo que la esfera político-administrativa espera de los científicos y la forma en que estos últimos ven como efectiva y útil su participación. Además, se observaron fallas de coordinación entre quien financia la investigación y quien genera la política pública. Los resultados también muestran que las brechas entre las esferas no se recducen únicamente al campo del cambio climático, sino que se deben también a la manera como están conformadas las estructuras científicas y políticas de Chile.https://revistas.unal.edu.co/index.php/recs/article/view/66402311-332vol.40Not indexed
Agua y Extremos2017Locatelli, B., Aldunce, P., Fallot, A., Le Coq, J. F., Sabourin, E., Tapasco, J.Research on Climate Change Policies and Rural Development in Latin America: Scope and GapsSustainability10.3390/su9101831Research on climate change policies can contribute to policy development by building an understanding of the barriers faced in policy processes, and by providing knowledge needed throughout policy cycles. This paper explores the thematic coverage of research on climate change policies related to rural areas, rural development, and natural resource management in Latin America. A three-tier framework is proposed to analyse the selected literature. The results show that research studies have focussed on the mitigation of greenhouse gas emissions from forests, and adaptations to climate change in agriculture. There is little policy research on other vulnerable sectors (e.g., water and health) and emitting sectors (e.g., energy and industry) in the context of rural development. Our analysis highlights the various research gaps that deserve increased scientific attention, including: cross-sector approaches, multi-level governance, and the stages of policy adoption, implementation and evaluation. In addition, the selected literature has a limited contribution to theoretical discussions in policy sciences.http://www.mdpi.com/2071-1050/9/10/18311831vol.9Thomson Reuters ISI
Agua y Extremos2017Massmann, A. K., Minder, J.R., Garreaud, R. D., Kingsmill, D. E., Valenzuela, R. A., Montecinos, A., Fults, S. L., Snider, J. R.The Chilean Coastal Orographic Precipitation Experiment: Observing the Influence of Microphysical Rain Regimes on Coastal Orographic PrecipitationJournal of HydrometeorologyVer ficha10.1175/JHM-D-17-0005.1The Chilean Coastal Orographic Precipitation Experiment (CCOPE) was conducted during the austral winter of 2015 (May-August) in the Nahuelbuta Mountains (peak elevation 1.3 km MSL) of southern Chile (38°S). CCOPE used soundings, two profiling Micro Rain Radars, a Parsivel disdrometer, and a rain gauge network to characterize warm and ice-initiated rain regimes and explore their consequences for orographic precipitation. Thirty-three percent of foothill rainfall fell during warm rain periods, while 50% of rainfall fell during ice-initiated periods. Warm rain drop size distributions were characterized by many more and relatively smaller drops than ice-initiated drop size distributions. Both the portion and properties of warm and ice-initiated rainfall compare favorably with observations of coastal mountain rainfall at a similar latitude in California. Orographic enhancement is consistently strong for rain of both types, suggesting that seeding from ice aloft is not a requisite for large orographic enhancement. While the data suggest that orographic enhancement may be greater during warm rain regimes, the difference in orographic enhancement between regimes is not significant. Sounding launches indicate that differences in orographic enhancement are not easily explainable by differences in low-level moisture flux or nondimensional mountain height between the regimes.http://journals.ametsoc.org/doi/10.1175/JHM-D-17-0005.12723-2743vol.18Thomson Reuters ISI
Agua y Extremos; Gobernanza e Interfaz entre Ciencia y Política2017Aldunce, P., Araya, D., Sapiain, R., Ramos, I., Lillo, G., Urquiza, A., Garreaud, R.
Local Perception of Drought Impacts in a Changing Climate: The Mega-Drought in Central Chile
10.3390/su9112053Droughts are a recurrent and complex natural hazard whose frequency and magnitude are expected to increase with climate change. Despite the advances in responding and adapting to droughts (with the development of new policies, for example), droughts continue to cause serious impacts and suffering. Developing well-targeted public policies requires further research on adaptation. Specifically, understanding the public perception of drought can help to identify drivers of and barriers to adaptation and options. This research seeks to understand the public perception of drought in central Chile in order to inform adaptation-related policies and decision-making processes. This study focused on the Mega-drought, which was a protracted dry spell afflicting central Chile since 2010.http://www.mdpi.com/2071-1050/9/11/20532053vol.9Thomson Reuters ISI
Agua y Extremos2018Barria, P., Peel, M. C., Walsh, K. J. E., Muñoz, A.The first 300-year streamflow reconstruction
of a high-elevation river in Chile using tree rings
International Journal of Climatology10.1002/joc.5186In central Chile, increasing demand for water and decreasing runoff volumes due to drier conditions have placed catchments in this zone under water stress. However, scarcity of observed data records increases the difficulty of planning future water supply. Instrumental records suggest a reduction in streamflow over the last 56 years. However, this change is not statistically significant and the lack of meteorological stations with long records in this mountainous region hampers a deeper analysis, motivating the use of tree rings to analyse whether these changes are part of a long-term trend. This work represents the first high-elevation runoff reconstruction in Chile using 300 years of tree ring chronologies of Araucaria araucana and Astroceudrus chilensis. The upper part of Biobío river melting season runoff (October–March) and pluvial season runoff (April–September) was reconstructed and analysed to investigate the influence of large-scale climatic drivers on runoff generation, current drought trends and to improve the understanding of climate variability in this region. We obtained positive correlations between the 20-year moving average of reconstructed pluvial season runoff and reconstructed Pacific Decadal Oscillation (PDO), which is indicative of multi-decadal variability. We also found a negative correlation between the 11-year moving average of reconstructed melting season runoff and the PDO and positive correlations with the Southern Annular Mode (SAM). Important differences in the runoff variability of the upper and the lower part of the catchment were identified which are in part led by the influence of the large-scale climatic features that drive runoff generation in both regions. We found that the changes observed in the instrumental records are part of multi-decadal cycles led by the PDO and SAM for pluvial season runoff and melting season runoff, respectively.http://doi.wiley.com/10.1002/joc.5186436-451vol.38 is.1Thomson Reuters ISI
Agua y Extremos2018León-Muñoz, J., Urbina, M. A., Garreaud, R., Iriarte, J. L.Hydroclimatic conditions trigger record harmful algal bloom in western Patagonia (summer 2016)Scientific ReportsVer ficha10.1038/s41598-018-19461-4A harmful algal bloom (HAB) of the raphidophyta alga Pseudochattonella cf. verruculosa during the 2016 austral summer (February-March) killed nearly 12% of the Chilean salmon production, causing the worst mass mortality of fish and shellfish ever recorded in the coastal waters of western Patagonia. The HAB coincided with a strong El Ninõ event and the positive phase of the Southern Annular Mode that altered the atmospheric circulation in southern South America and the adjacent Pacific Ocean. This led to very dry conditions and higher than normal solar radiation reaching the surface. Using time series of atmospheric, hydrologic and oceanographic data we show here that an increase in surface water temperature and reduced freshwater input resulted in a weakening of the vertical stratification in the fjords and sounds of this region. This allowed the advection of more saline and nutrient-rich waters, ultimately resulting in an active harmful algal bloom in coastal southern Chile.http://www.nature.com/articles/s41598-018-19461-4vol.8 is.1Thomson Reuters ISI
Agua y Extremos2018Garreaud, R. D.A plausible atmospheric trigger for the 2017 coastal El Niño: THE 2017 COASTAL EL NIÑOInternational Journal of ClimatologyVer ficha10.1002/joc.5426The far eastern tropical Pacific experienced a rapid, marked warming in early 2017, causing torrential rains along the west coast of South America with a significant societal toll in Peru and Ecuador. This strong coastal El Niño was largely unpredicted, even a few weeks before its onset, and it developed differently from either central or eastern events. Here we provide an overview of the event, its impacts and concomitant atmospheric circulation. It is proposed that a remotely forced, sustained weakening of the free tropospheric westerly flow impinging the subtropical Andes leads to a relaxation of the southeasterly (SE) trades off the coast, which in turn may have warmed the eastern Pacific throughout the weakening of upwelling in a near-coastal band and the lessening of the evaporative cooling farther offshore.http://doi.wiley.com/10.1002/joc.5426Thomson Reuters ISI
Agua y Extremos2018Garreaud, R. D.
Record-breaking climate anomalies lead to severe drought and environmental disruption in western Patagonia in 2016
Climate Research
Ver ficha10.3354/cr01505Traditionally a temperate and hyper-humid region, western Patagonia experienced its most severe drought during the summer and fall of 2016. Along with precipitation deficits larger than 50% there was a similar reduction in river discharge into coastal waters, a decline in vegetation productivity, excessive solar radiation at the surface, and frequent upwelling-favorable wind events offshore. The combination of these regional-scale anomalies seems to have set the stage for environmental disturbances that, although not new in western Patagonia, occurred with unprecedented magnitude, including severe urban air pollution episodes, large forest fires, and the worst ever recorded harmful algae bloom (HAB). The local climate anomalies were in turn related to the concomitant strong El Niño (through atmospheric teleconnections) and, to a lesser extent, anthropogenic climate change mediated by the positive polarity of the Southern Annular Mode (SAM) and internal variability, as both modes weakened the westerlies. Dryer than present conditions are consistently projected for northern Patagonia during the 21st century as a consequence of anthropogenic increases in radiative forcing; superposition of El Niño events in this altered climate may result in a higher frequency of extreme droughts and environmental disruptions like those observed in 2016.http://www.int-res.com/abstracts/cr/v74/n3/p217-229/217-229vol.74 is.3Thomson Reuters ISI
Agua y Extremos; Cambio de Uso de Suelo; Ciudades Resilientes; Gobernanza e Interfaz Ciencia y Política2018Moreno, P. I., Vilanova, I., Villa-Martinez, R., Dunbar, R. B., Mucciarone, D. A., Kaplan, M. R., Garreaud, R., Rojas, M., De Polz-Holz, R., Lambert, F.
Onset and Evolution of Southern Annular Mode-Like Changes at Centennial Timescale
Scientific Reports
Ver ficha10.1038/s41598-018-21836-6
The Southern Westerly Winds (SWW) are the surface expression of geostrophic winds that encircle the southern mid-latitudes. In conjunction with the Southern Ocean, they establish a coupled system that not only controls climate in the southern third of the world, but is also closely connected to the position of the Intertropical Convergence Zone and CO2 degassing from the deep ocean. Paradoxically, little is known about their behavior since the last ice age and relationships with mid-latitude glacier history and tropical climate variability. Here we present a lake sediment record from Chilean Patagonia (51°S) that reveals fluctuations of the low-level SWW at mid-latitudes, including strong westerlies during the Antarctic Cold Reversal, anomalously low intensity during the early Holocene, which was unfavorable for glacier growth, and strong SWW since ∼7.5 ka. We detect nine positive Southern Annular Mode-like events at centennial timescale since ∼5.8 ka that alternate with cold/wet intervals favorable for glacier expansions (Neoglaciations) in southern Patagonia. The correspondence of key features of mid-latitude atmospheric circulation with shifts in tropical climate since ∼10 ka suggests that coherent climatic shifts in these regions have driven climate change in vast sectors of the Southern Hemisphere at centennial and millennial timescales.http://www.nature.com/articles/s41598-018-21836-6vol.8 is.1Thomson Reuters ISI
Agua y Extremos2017González, S., Garreaud, R.Spatial variability of near-surface temperature over the coastal mountains in southern Chile (38°S)Meteorology and Atmospheric PhysicsVer ficha10.1007/s00703-017-0555-4The spatial distribution of the near-surface air temperature over a coastal mountain range in southern Chile [Nahuelbuta Mountains (NM), 38°S, maximum height 1300-m ASL] is investigated using in situ measurements, satellite-derived land-surface temperature, and simulations during the austral winter of 2011. Based on a few selected but representative cases, we found that under rainy conditions—either at day or night—temperature decreases with height close to the moist adiabatic lapse rate (~6.5 °C/km). Likewise, the temperature tends to follow the dry adiabat (~9.8 °C/km) during daytime under dry- and clear-skies conditions. During clear-skies nights, the temperature also decreases with height over the southeastern side of NM, but it often increases (at about 8 °C/km) over the northwestern side of the mountains. This temperature inversion extends up to about 700-m ASL leading to an average temperature contrast of about 7 °C between the northwestern and southeastern sides of Nahuelbuta by the end of dry nights. These dawns also feature substantial temperature differences (>10 °C) among closely located stations at a same altitude. High-resolution numerical simulations suggest that upstream blocking of the prevailing SE flow, hydrostatic mountain waves, and strong downslope winds is responsible for such distinctive nocturnal temperature distribution.http://link.springer.com/10.1007/s00703-017-0555-4Thomson Reuters ISI
Agua y Extremos2017Rojas-Badilla, M., Álvarez, C., Velásquez-Álvarez, G., Hadad, M., Le Quesne, C., Christie, D. A.
Anomalías anatómicas en anillos de crecimiento anuales de Austrocedrus chilensis (D. Don) Pic.-Serm. et Bizzarri en el norte de su rango de distribuciónGayana. Botánica10.4067/S0717-66432017000200269Tree-ring anatomical anomalies have received little attention in southern South American trees, however they can contain valuable intra-annual environmental information. This study addressed for the first time the three most frequent tree- ring anomalies recorded in the northern and oldest known Austrocedrus chilensis forest in central Chile (32-35°S). Three anatomic anomalies described were: partially absent rings, intra-annual bands and frost rings. Partially absent rings resulted from cambial inactivity during a complete growing period and require dendrochronological tools to be detected. Intra- annual bands are consequence of the abundance-shortage of environmental resources during the growing season and can be detected by examining the undefined late-wood boundaries. Frost rings, are caused by extreme low temperatures and are characterized by collapsed cells in the tree-ring growth. Results indicate that the northern most population exhibited the highest rate of absent rings, while the occurrence of intra-annual bands seems to be rather minor in the study area. Finally, frost rings are registered mainly in the younger trees in all three studied sites. These results suggest the potential for future spatio-temporal studies that examine the frequency of these anatomical anomalies in A. chilensis chronologies along its wide geographical distribution. This will complement the current environmental information recorded by its growth rates.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-66432017000200269&lng=en&nrm=iso&tlng=en269-281vol.74 is.2Thomson Reuters ISI, ScieLO
Agua y Extremos; Cambio de Uso de Suelo2018Urrutia-Jalabert, R., González, M. E., González-Reyes, A., Lara, A., Garreaud, R.Climate variability and forest fires in central and south-central ChileEcosphere10.1002/ecs2.2171This paper evaluates the relationship between fire occurrence (number and burned area) and
climate variability (precipitation and maximum temperatures) across central and south-central Chile
(32°–43° S) during recent decades (1976–2013). This region sustains the largest proportion of the Chilean
population, contains ecologically important remnants of endemic ecosystems, the largest extension of
forest exotic plantations, and concentrates most of the fire activity in the country. Fire activity in central
Chile was mainly associated with above-average precipitation during winter of the previous year and
with dry conditions during spring to summer. The later association was particularly strong in the southern,
wetter part of the study region. Maximum temperature had a positive significant relationship with
burned area across the study region, with stronger correlations toward the south. Fires in central Chile
were significantly related to El Nino~ –Southern Oscillation, through rainfall anomalies during the year
previous to the fire season. The Antarctic Oscillation during winter through summer was positively
related to fires across the study area due to drier/warmer conditions associated with the positive polarity
of this oscillation. Climate change projections for the region reveal an all-season decrease in precipitation
and increases in temperature, that may likely result in an increment of the occurrence and the area
affected by fires, as it has been observed during a multi-year drought afflicting central Chile since 2010.
http://doi.wiley.com/10.1002/ecs2.2171e02171vol.9 is.4Thomson Reuters ISI
Agua y Extremos; Zonas Costeras; Transversal
2018Bozkurt, D., Rondanelli, R., Marín, J. C., Garreaud, R.
Bozkurt, D., Rondanelli, R., Marín, J. C., Garreaud, R.
Journal of Geophysical Research: Atmospheres10.1002/2017JD027796A record‐setting temperature of 17.5°C occurred on 24 March 2015 at the Esperanza station located near the northern tip of the Antarctic Peninsula (AP). We studied the event using surface station data, satellite imagery, reanalysis data, and numerical simulations. The Moderate Resolution Imaging Spectroradiometer Antarctic Ice Shelf Image Archive provides clear evidence for disintegration and advection of sea ice, as well as the formation of melt ponds on the ice sheet surface at the base of the AP mountain range. A deep low‐pressure center over the Amundsen‐Bellingshausen Sea and a blocking ridge over the southeast Pacific provided favorable conditions for the development of an atmospheric river with a northwest‐southeast orientation, directing warm and moist air toward the AP, and triggering a widespread foehn episode. A control simulation using a regional climate model shows the existence of local topographically induced warming along the northern tip of the AP (∼60% of the full temperature signal) and the central part of the eastern AP (>90% of the full temperature signal) with respect to a simulation without topography. These modeling results suggest that more than half of the warming experienced at Esperanza can be attributed to the foehn effect (a local process), rather than to the large‐scale advection of warm air from the midlatitudes. Nevertheless, the local foehn effect also has a large‐scale advection component, since the atmospheric river provides water vapor for orographic precipitation enhancement and latent heat release, which makes it difficult to completely disentangle the role of local versus large‐scale processes in explaining the extreme event.http://doi.wiley.com/10.1002/2017JD0277963871-3892vol.123 is.8Thomson Reuters ISI
Agua y Extremos2018Moreno, P. I., Vilanova, I., Villa-Martínez, R. P., Francois, J. P.,Modulation of Fire Regimes by Vegetation and Site Type in Southwestern Patagonia Since 13 kaFrontiers in Ecology and Evolution10.3389/fevo.2018.00034The degree to which vegetation and site type have influenced fire regimes through the Holocene has not been investigated in detail in the temperate ecosystems of southern Patagonia. Here we present a first attempt using a paired-basin approach to study the evolution of fire regimes in sectors dominated by humid Nothofagus forests and the xeric Patagonian steppe in the Magallanes region of Chilean Patagonia (51°S). We analyzed sediment cores from two small lakes and a bog located within the same climate zone on opposite sides of the forest-steppe ecotone, ~28 km apart. The position of this biological boundary east of the Andes is controlled by the strength and position of the southern westerly winds, which constitute the sole source of precipitation throughout western Patagonia. Our results indicate that fires have occurred in the study region repeated times over the last ~13,000 years at bi- and tridecadal timescales. Sectors currently dominated by Patagonian steppe feature high frequency and low magnitude of local fires, and vice versa in humid forests. Climate-driven expansion of Nothofagus scrubland/woodland into steppe environments over the last ~4,200 years increased the magnitude and lowered the frequency of fire events, culminating with peak Nothofagus abundance, fire magnitude and frequency during the last millennium. We also detect divergences between lake-based vs. bog-based paleofire histories among paired sites located within the Patagonian steppe, ~12 km apart, which we attribute to local burning of the bog at times of lowered water table. This divergence suggests to us that bog-based vegetation and fire histories exacerbate a local, azonal, signal blurring extra-local or regional regimes, thus accounting for some discrepancies in the Quaternary paleovegetation/paleoclimate literature of southern Patagonia.http://journal.frontiersin.org/article/10.3389/fevo.2018.00034/fullvol.6Scopus
Agua y Extremos; Cambio de Uso de Suelo2017Simi, E., Moreno, P. I., Villa-Martínez, R., Vilanova, I., de Pol-Holz, R.Climate change and resilience of deciduous Nothofagus forests in central-east Chilean Patagonia over the last 3200 years: RESILIENCE OF DECIDUOUS NOTHOFAGUS FORESTS IN PATAGONIAJournal of Quaternary Science10.1002/jqs.2948We examine the response of Nothofagus forests to climate change and disturbance regimes over the last 3200 years near Coyhaique (45°S), central–east Chilean Patagonia, using fine‐resolution pollen and charcoal records from lake sediment cores. Closed‐canopy deciduous Nothofagus forests have dominated the region with little variation until the arrival of Chilean–European settlers, suggesting a predominance of cool‐temperate and wet conditions. Within this state we identify centennial‐scale episodes of forest fragmentation, increase in littoral macrophytes and volcanic/paleofire disturbance between 2700 and 3000 cal a BP, 2200 and 2500 cal a BP and over the last ∼250 years, which we interpret as intervals with negative hydrologic balance. Natural variability caused little impact on the physiognomy and composition of the vegetation in pre‐European time, in contrast to the accelerated shift that started during the late 19th century associated with deforestation, homogenization and synchronization of ecosystem changes at the landscape level, and spread of exotic plant species brought by Chilean and European settlers during a warm/dry interval. The resilience of deciduous Nothofagus forests to natural disturbance regimes and climate change was exceeded by large‐scale human disturbance since the late 19th century by fire, timber exploitation and livestock grazing. These disturbances caused an ecosystem shift towards artificial meadows and scrublands with frequent high‐magnitude fires.http://doi.wiley.com/10.1002/jqs.2948845-856vol.32 is.6Thomson Reuters ISI
Agua y Extremos2018Baez-Villanueva, O. M., Zambrano-Bigiarini, M., Ribbe, L., Nauditt, A., Giraldo-Osorio, J.D., Thinh, N.X.
Temporal and spatial evaluation of satellite rainfall estimates over different regions in Latin-America
Atmospheric Research
In developing countries, an accurate representation of the spatio-temporal variability of rainfall is currently severely limited, therefore, satellite-based rainfall estimates (SREs) are promising alternatives. In this work, six state-of-the-art SREs (TRMM 3B42v7, TRMM 3B42RT, CHIRPSv2, CMORPHv1, PERSIANN-CDR, and MSWEPv2) are evaluated over three different basins in Latin-America, using a point-to-pixel comparison at daily, monthly, and seasonal timescales. Three continuous (root mean squared error, modified Kling-Gupta efficiency, and percent bias) and three categorical (probability of detection, false alarm ratio, and frequency bias) indices are used to evaluate the performance of the different SREs, and to assess if the upscaling procedure used, in CHIRPSv2 and MSWEPv2, to enable a consistent point-to-pixel comparison affects the evaluation of the SREs performance at different time scales.

Our results show that for Paraiba do Sul in Brazil, MSWEPv2 presented the best performance at daily and monthly time scales, while CHIRPSv2 performed the best at these timescales over the Magdalena River Basin in Colombia. In the Imperial River Basin in Chile, MSWEPv2 and CHIRPSv2 performed the best at daily and monthly time scales, respectively. When the basins were evaluated at seasonal scale, CMORPHv1 performed the best for DJF and SON, TRMM 3B42v7 for MAM, and PERSIANN-CDR for JJA over Imperial Basin. MSWEPv2 performed the best over Paraiba do Sul Basin for all seasons and CHIRPSv2 showed the best performance over Magdalena Basin. The Modified Kling-Gupta efficiency (KGE′) proved to be a useful evaluation index because it decomposes the performance of the SREs into linear correlation, bias, and variability parameters, while the Root Mean Squared Error (RMSE) is not recommended for evaluating SREs performance because it gives more weight to high rainfall events and its results are not comparable between areas with different precipitation regimes.

On the other hand, CHIRPSv2 and MSWEPv2 presented different performance, for some study areas and time scales, when evaluated with their original spatial resolution (0.05° and 0.1, respectively) with respect to the evaluation resulting after applying the spatial upscaling (to a unified 0.25), showing that the upscaling procedure might impact the SRE performance. We finally conclude that a site-specific validation is needed before using any SRE, and we recommend to evaluate the SRE performance before and after applying any upscaling procedure in order to select the SRE that best represents the spatio-temporal precipitation patterns of a site.
http://linkinghub.elsevier.com/retrieve/pii/S0169809517313029Thomson Reuters ISI
Agua y Extremos2018Fernández, A., Muñoz, A., González-Reyes, A., Aguilera-Betti, I., Toledo, I., Puchi, P., Sauchyn, D., Crespo, S., Frene, C., Mundo, I., González, M., Vignola, R.Dendrohydrology and water resources management in south-central Chile: lessons from the Río Imperial streamflow reconstructionHydrology and Earth System Sciences10.5194/hess-22-2921-2018Streamflow in south-central Chile (SCC,  ∼  37–42° S) is vital for agriculture, forestry production, hydroelectricity, and human consumption. Recent drought episodes have generated hydrological deficits with damaging effects on these activities. This region is projected to undergo major reductions in water availability, concomitant with projected increases in water demand. However, the lack of long-term records hampers the development of accurate estimations of natural variability and trends. In order to provide more information on long-term streamflow variability and trends in SCC, here we report findings of an analysis of instrumental records and a tree-ring reconstruction of the summer streamflow of the Río Imperial ( ∼  37° 40′ S–38° 50′ S). This is the first reconstruction in Chile targeted at this season. Results from the instrumental streamflow record ( ∼  1940 onwards) indicated that the hydrological regime is fundamentally pluvial with a small snowmelt contribution during spring, and evidenced a decreasing trend, both for the summer and the full annual record. The reconstruction showed that streamflow below the average characterized the post-1980 period, with more frequent, but not more intense, drought episodes. We additionally found that the recent positive phase of the Southern Annular Mode has significantly influenced streamflow. These findings agree with previous studies, suggesting a robust regional signal and a shift to a new hydrological scenario. In this paper, we also discuss implications of these results for water managers and stakeholders; we provide rationale and examples that support the need for the incorporation of tree-ring reconstructions into water resources management.https://www.hydrol-earth-syst-sci.net/22/2921/2018/2921-2935vol.22 is.5Thomson Reuters ISI