Central Chile, home to more than 10 million inhabitants, has experienced an uninterrupted sequenc... more Central Chile, home to more than 10 million inhabitants, has experienced an uninterrupted sequence of dry years since 2010 with mean rainfall deficits of 20–40%. The so‐called Mega Drought (MD) is the longest event on record and with few analogues in the last millennia. It encompasses a broad area, with detrimental effects on water availability, vegetation and forest fires that have scaled into social and economical impacts. Observations and reanalysis data reveal that the exceptional length of the MD results from the prevalence of a circulation dipole‐hindering the passage of extratropical storms over central Chile—characterized by deep tropospheric anticyclonic anomalies over the subtropical Pacific and cyclonic anomalies over the Amundsen–Bellingshausen Sea. El Niño Southern Oscillation (ENSO) is a major modulator of such dipole, but the MD has occurred mostly under ENSO‐neutral conditions, except for the winters of 2010 (La Niña) and 2015 (strong El Niño). Climate model simulati...
There is strong evidence of El Niño‐Southern Oscillation (ENSO) teleconnections in the South Paci... more There is strong evidence of El Niño‐Southern Oscillation (ENSO) teleconnections in the South Pacific and related impacts on the precipitation regime in Chile; nonetheless, many aspects of the hydrological propagation and temperature responses to ENSO remain unclear in this region. We examine fluctuations across 59 near‐natural catchments in central Chile (28°–41°S) under contrasting ENSO phases during the period 1981–2019. Our results show statistically significant ENSO‐related hydroclimatic anomalies in almost all watersheds analyzed, which confirms the major influence of ENSO within this domain. By comparing El Niño phases against La Niña, we observe generally wetter conditions, warmer winters, cooler late springs, lower (higher) runoff ratios in snowmelt‐driven (rainfall‐driven) basins, and longer storm durations while storm frequencies (i.e., number of events of consecutive days with precipitation) are preserved. Additionally, low (high) elevation catchments are related to posit...
CAMELS-CL relies on multiple data sources (including ground data, remote-sensed products and rean... more CAMELS-CL relies on multiple data sources (including ground data, remote-sensed products and reanalyses) to characterise the hydroclimatic conditions and landscape of a region where in situ measurements are scarce. The dataset includes 516 catchments and provides boundaries, daily streamflow records and basin-averaged daily time series of precipitation (from one national and three global datasets), maximum, minimum and mean temperatures, potential evapotranspiration (PET; from two datasets), and snow water equivalent. We calculated hydro-climatological indices using these time series, and leveraged diverse data sources to extract topographic, geological and land cover features. Relying on publicly available reservoirs and water rights data for the country, we estimated the degree of anthropic intervention within the catchments. To facilitate the use of this dataset and promote common standards in large-sample studies, we computed most catchment attributes introduced by Addor et al. (2017) in their Catchment Attributes and MEteorology for Large-sample Studies (CAMELS) dataset (doi:10.5065/D6G73C3Q), and added several others.---CAMELS-CL can be visualised from http://camels.cr2.cl---This research emerged from the collaboration with many colleagues at the Center for Climate and Resilience Research (CR2, CONICYT/FONDAP/15110009). Camila Alvarez-Garreton was funded by FONDECYT postdoctoral grant no. 3170428. Pablo Mendoza received additional support from FONDECYT postdoctoral grant no. 3170079. Mauricio Zambrano-Bigiarini thanks FONDECYT 11150861 for financial support. The development of CR2MET was supported by the Chilean Water Directorate (DGA), through National Water Balance Updating Project DGA-2319, and by FONDECYT grant no. 3150492. This study is a contribution to the Large-sample Hydrology working group of the Panta Rhei Research Initiative of the International Association of Hydrological Sciences (IAHS).
Le changement de l'occupation des sols (LUC) a une influence importante sur le climat de par ... more Le changement de l'occupation des sols (LUC) a une influence importante sur le climat de par les modifications des proprietes physiques de la surface. Le niveau de connaissance de ces impacts biogeophysiques est cependant insuffisant, en raison notamment des nombreux processus impliques. Via l'intercomparaison de modeles de climat et d'autres outils developpes, cette these vise a identifier les signaux climatiques robustes lies au LUC, ainsi qu'a evaluer les incertitudes associees. Depuis l'epoque preindustrielle, le LUC a resulte en une deforestation extensive dans les regions temperees de l'hemisphere Nord, ou l'augmentation de l'albedo de surface a surement induit un refroidissement durant l'hiver et le printemps. L'amplitude de cet impact ainsi que le role des effets non radiatifs en ete reste pourtant tres incertain parmi les modeles. Ces incertitudes repondent (1) a la facon dont le LUC est represente dans les modeles de surface et (2) a...
In this study, we explored the connection between anomalies in springtime Antarctic ozone and all... more In this study, we explored the connection between anomalies in springtime Antarctic ozone and all-year precipitation in the Southern Hemisphere by using observations from 1960–2018 and coupled simulations for 1960–2050. The observations showed that this correlation was enhanced during the last several decades, when a simultaneously increased coupling between ozone and Southern Annular Mode (SAM) anomalies became broader, covering most of the following summer and part of the previous winter. For eastern Australia, the ozone–precipitation connection shows a greater persistence toward the following summer than for other regions. On the other hand, for South America, the ozone–precipitation correlation seems more robust, especially in the early summer. There, the correlation also covers part of the previous winter, suggesting that winter planetary waves could affect both parameters. Further, we estimated the sensitivity of precipitation to changes in Antarctic ozone. In both observation...
Over the past 40 years, south-central Chile has experienced important land-use-induced land cover... more Over the past 40 years, south-central Chile has experienced important land-use-induced land cover changes, with massive conversion from native forests (NF) to Pinus radiata D.Don and Eucalyptus spp. exotic forest plantations (FP). Several case studies have related this conversion to a reduction in water supply within small catchments (<100 ha). In this work, we explore the impacts of NF and FP on streamflow by using a large-sample catchment dataset recently developed for Chile. We select 25 large forested catchments (>20,000 ha) in south-central Chile (35° S–41° S), analyze their land cover and precipitation spatial distributions, and fit a regression model to quantify the influence of NF, FP, grassland (GRA) and shrubland (SHR) partitions on annual runoff. To assess potential effects of land cover changes on water supply, we use the fitted model (R2 = 0.84) in synthetic experiments where NF, GRA and SHR covers within the catchments are replaced by patches of FP. We show that ...
Within large uncertainties in the precipitation response to greenhouse gas forcing, the Southeast... more Within large uncertainties in the precipitation response to greenhouse gas forcing, the Southeast Pacific drying stands out as a robust signature within climate models. A precipitation decline, of consistent direction but of larger amplitude than obtained in simulations with historical climate forcing, has been observed in central Chile since the late 1970s. To attribute the causes of this trend, we analyze local rain gauge data and contrast them to a large ensemble of both fully coupled and sea surface temperature‐forced simulations. We show that in concomitance with large‐scale circulation changes, the Pacific Decadal Oscillation explains about half of the precipitation trend observed in central Chile. The remaining fraction is unlikely to be driven exclusively by natural phenomena but rather consistent with the simulated regional effect of anthropogenic climate change. We particularly estimate that a quarter of the rainfall deficit affecting this region since 2010 is of anthropog...
Central Chile, home to more than 10 million inhabitants, has experienced an uninterrupted sequenc... more Central Chile, home to more than 10 million inhabitants, has experienced an uninterrupted sequence of dry years since 2010 with mean rainfall deficits of 20–40%. The so‐called Mega Drought (MD) is the longest event on record and with few analogues in the last millennia. It encompasses a broad area, with detrimental effects on water availability, vegetation and forest fires that have scaled into social and economical impacts. Observations and reanalysis data reveal that the exceptional length of the MD results from the prevalence of a circulation dipole‐hindering the passage of extratropical storms over central Chile—characterized by deep tropospheric anticyclonic anomalies over the subtropical Pacific and cyclonic anomalies over the Amundsen–Bellingshausen Sea. El Niño Southern Oscillation (ENSO) is a major modulator of such dipole, but the MD has occurred mostly under ENSO‐neutral conditions, except for the winters of 2010 (La Niña) and 2015 (strong El Niño). Climate model simulati...
There is strong evidence of El Niño‐Southern Oscillation (ENSO) teleconnections in the South Paci... more There is strong evidence of El Niño‐Southern Oscillation (ENSO) teleconnections in the South Pacific and related impacts on the precipitation regime in Chile; nonetheless, many aspects of the hydrological propagation and temperature responses to ENSO remain unclear in this region. We examine fluctuations across 59 near‐natural catchments in central Chile (28°–41°S) under contrasting ENSO phases during the period 1981–2019. Our results show statistically significant ENSO‐related hydroclimatic anomalies in almost all watersheds analyzed, which confirms the major influence of ENSO within this domain. By comparing El Niño phases against La Niña, we observe generally wetter conditions, warmer winters, cooler late springs, lower (higher) runoff ratios in snowmelt‐driven (rainfall‐driven) basins, and longer storm durations while storm frequencies (i.e., number of events of consecutive days with precipitation) are preserved. Additionally, low (high) elevation catchments are related to posit...
CAMELS-CL relies on multiple data sources (including ground data, remote-sensed products and rean... more CAMELS-CL relies on multiple data sources (including ground data, remote-sensed products and reanalyses) to characterise the hydroclimatic conditions and landscape of a region where in situ measurements are scarce. The dataset includes 516 catchments and provides boundaries, daily streamflow records and basin-averaged daily time series of precipitation (from one national and three global datasets), maximum, minimum and mean temperatures, potential evapotranspiration (PET; from two datasets), and snow water equivalent. We calculated hydro-climatological indices using these time series, and leveraged diverse data sources to extract topographic, geological and land cover features. Relying on publicly available reservoirs and water rights data for the country, we estimated the degree of anthropic intervention within the catchments. To facilitate the use of this dataset and promote common standards in large-sample studies, we computed most catchment attributes introduced by Addor et al. (2017) in their Catchment Attributes and MEteorology for Large-sample Studies (CAMELS) dataset (doi:10.5065/D6G73C3Q), and added several others.---CAMELS-CL can be visualised from http://camels.cr2.cl---This research emerged from the collaboration with many colleagues at the Center for Climate and Resilience Research (CR2, CONICYT/FONDAP/15110009). Camila Alvarez-Garreton was funded by FONDECYT postdoctoral grant no. 3170428. Pablo Mendoza received additional support from FONDECYT postdoctoral grant no. 3170079. Mauricio Zambrano-Bigiarini thanks FONDECYT 11150861 for financial support. The development of CR2MET was supported by the Chilean Water Directorate (DGA), through National Water Balance Updating Project DGA-2319, and by FONDECYT grant no. 3150492. This study is a contribution to the Large-sample Hydrology working group of the Panta Rhei Research Initiative of the International Association of Hydrological Sciences (IAHS).
Le changement de l'occupation des sols (LUC) a une influence importante sur le climat de par ... more Le changement de l'occupation des sols (LUC) a une influence importante sur le climat de par les modifications des proprietes physiques de la surface. Le niveau de connaissance de ces impacts biogeophysiques est cependant insuffisant, en raison notamment des nombreux processus impliques. Via l'intercomparaison de modeles de climat et d'autres outils developpes, cette these vise a identifier les signaux climatiques robustes lies au LUC, ainsi qu'a evaluer les incertitudes associees. Depuis l'epoque preindustrielle, le LUC a resulte en une deforestation extensive dans les regions temperees de l'hemisphere Nord, ou l'augmentation de l'albedo de surface a surement induit un refroidissement durant l'hiver et le printemps. L'amplitude de cet impact ainsi que le role des effets non radiatifs en ete reste pourtant tres incertain parmi les modeles. Ces incertitudes repondent (1) a la facon dont le LUC est represente dans les modeles de surface et (2) a...
In this study, we explored the connection between anomalies in springtime Antarctic ozone and all... more In this study, we explored the connection between anomalies in springtime Antarctic ozone and all-year precipitation in the Southern Hemisphere by using observations from 1960–2018 and coupled simulations for 1960–2050. The observations showed that this correlation was enhanced during the last several decades, when a simultaneously increased coupling between ozone and Southern Annular Mode (SAM) anomalies became broader, covering most of the following summer and part of the previous winter. For eastern Australia, the ozone–precipitation connection shows a greater persistence toward the following summer than for other regions. On the other hand, for South America, the ozone–precipitation correlation seems more robust, especially in the early summer. There, the correlation also covers part of the previous winter, suggesting that winter planetary waves could affect both parameters. Further, we estimated the sensitivity of precipitation to changes in Antarctic ozone. In both observation...
Over the past 40 years, south-central Chile has experienced important land-use-induced land cover... more Over the past 40 years, south-central Chile has experienced important land-use-induced land cover changes, with massive conversion from native forests (NF) to Pinus radiata D.Don and Eucalyptus spp. exotic forest plantations (FP). Several case studies have related this conversion to a reduction in water supply within small catchments (<100 ha). In this work, we explore the impacts of NF and FP on streamflow by using a large-sample catchment dataset recently developed for Chile. We select 25 large forested catchments (>20,000 ha) in south-central Chile (35° S–41° S), analyze their land cover and precipitation spatial distributions, and fit a regression model to quantify the influence of NF, FP, grassland (GRA) and shrubland (SHR) partitions on annual runoff. To assess potential effects of land cover changes on water supply, we use the fitted model (R2 = 0.84) in synthetic experiments where NF, GRA and SHR covers within the catchments are replaced by patches of FP. We show that ...
Within large uncertainties in the precipitation response to greenhouse gas forcing, the Southeast... more Within large uncertainties in the precipitation response to greenhouse gas forcing, the Southeast Pacific drying stands out as a robust signature within climate models. A precipitation decline, of consistent direction but of larger amplitude than obtained in simulations with historical climate forcing, has been observed in central Chile since the late 1970s. To attribute the causes of this trend, we analyze local rain gauge data and contrast them to a large ensemble of both fully coupled and sea surface temperature‐forced simulations. We show that in concomitance with large‐scale circulation changes, the Pacific Decadal Oscillation explains about half of the precipitation trend observed in central Chile. The remaining fraction is unlikely to be driven exclusively by natural phenomena but rather consistent with the simulated regional effect of anthropogenic climate change. We particularly estimate that a quarter of the rainfall deficit affecting this region since 2010 is of anthropog...
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