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artículo
Original abstract: Observations on glacier extent from Ecuador, Peru and Bolivia give a detailed and unequivocal account of rapid shrinkage of tropical Andean glaciers since the Little Ice Age (LIA). This retreat however, was not continuous but interrupted by several periods of stagnant or even advancing glaciers, most recently around the end of the 20th century. New data from mass balance networks established on over a dozen glaciers allows comparison of the glacier behavior in the inner and outer tropics. It appears that glacier variations are quite coherent throughout the region, despite different sensitivities to climatic forcing such as temperature, precipitation, humidity, etc. In parallel with the glacier retreat, climate in the tropical Andes has changed significantly over the past 50–60 years. Temperature in the Andes has increased by approximately 0.1 °C/decade, with only tw...
2
artículo
Publicado 2008
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Original abstract: A 41-year-long reconstructed annual mean glacier mass balance record from the Cordillera Blanca, Peru, was investigated for its climate sensitivity toward temperature, humidity and precipitation, and its links with the large-scale atmospheric circulation. On interannual timescales precipitation variability appears to be the main driver for glacier mass balance fluctuations in the Cordillera Blanca. This is corroborated by an analysis of the relationship between mass balance variations and local- to regional-scale precipitation variability. Temperature tends to enhance precipitation in driving the mass balance signal, as dry years are often characterized by warm conditions, while wet years usually coincide with cold anomalies. In some years, however, warm and wet or cold and dry conditions coincide, under which circumstances temperature minimizes or even neutralizes the...
3
documento de trabajo
Publicado 2023
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La variabilidad de la precipitación de verano en los Andes centrales (10-30° S, AC) en escala interdecenal (varias decenas de años), entre 1921 y 2010, se describe aplicando un filtro pasabanda para retener la variabilidad de más de 20 años en los índices de El Niño-Oscilación del Sur (Niño 1+2 [IN1+2] y Niño 4 [IN4]), la Oscilación Interdecenal del Pacífico (OIP), la Oscilación Multidecenal del Atlántico (OMA) y el reanálisis ERA-20C. La variabilidad interdecenal de las precipitaciones de los AC se describe mediante las “funciones ortogonales empíricas rotadas” (REOF). Los dos primeros modos REOF de precipitación representan el 40.4 % y 18.6 % de la varianza interdecenal total. El REOF1 presenta un patrón de precipitación tipo dipolo, es decir, con señales opuestas entre el norte de Bolivia y el Altiplano chileno. El REOF2 presenta un patrón de precipitación co...
4
artículo
Publicado 2022
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The impacts of the interdecadal variability of the Pacific and the Atlantic Oceans on precipitation over the Central Andes during the austral summer (December January-February, DJF) are investigated for the 1921–2010 period based on monthly gridded precipitation data and low-pass filtered time series of the Niño 4 index (IN4), the Niño 1 + 2 index with Niño 3.4 index removed (IN1+2*), Atlantic Multidecadal Oscillation (AMO), and Interdecadal Pacific Oscillation (IPO) indices, and the three first rotated principal components of the interdecadal component of the sea surface temperature (SST) anomalies over the Atlantic Ocean. A rotated empirical orthogonal function (REOF) analysis of precipitation in the Central Andes (10°S–30°S) yields two leading modes, RPC1 and RPC2, which represent 40.4% and 18.6% of the total variance, respectively. REOF1 features a precipitation dipole betwe...
5
artículo
Publicado 2016
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Extreme precipitation events in the Peruvian Andes have significant socioeconomic impacts, yet their atmospheric dynamics are poorly understood. Here austral summer (December–March) wet and dry spells and their continental- and large-scale teleconnections are analyzed using reanalysis, gridded, and in situ precipitation data. Dry and wet spells in the Peruvian Andes show a pervasive dipole pattern with precipitation anomalies of the opposite sign over northeastern Brazil. Composite anomalies of various atmospheric fields during extreme precipitation events indicate that this dipole is related to large-scale adjustments in the upper-tropospheric Bolivian high–Nordeste low system, which in turn are modulated by northward-propagating extratropical Rossby wave trains. At upper- and midtropospheric levels, westerly wind anomalies over the Peruvian Andes suppress moisture flux from the Ama...
6
documento de trabajo
Publicado 2019
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El objetivo central de este estudio es caracterizar los patrones de circulación atmosférica durante los episodios secos y lluviosos en época de verano en la cuenca del río Mantaro y su relación con el ENOS. La principal expectativa de nuestro estudio es que los resultados contribuyan al mejoramiento y desarrollo de técnicas de pronóstico de los eventos de lluvias extremas en los Andes centrales del Perú.
7
artículo
Publicado 2017
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El Niño in the eastern and central Pacific has different impacts on the rainfall of South America, and the atmospheric pathways through the South Pacific Convergence Zone (SPCZ) and Inter-Tropical Convergence Zone (ITCZ) are poorly understood. To address this, we performed linear regression analysis of E (eastern Pacific) and C (central Pacific) indices of sea surface temperature (SST), as well as precipitation indices for the SPCZ and ITCZ, with gridded precipitation and reanalysis data sets during the austral summer (December–February) for the 1980–2016 period.
8
documento de trabajo
Publicado 2018
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El principal objetivo de este estudio es caracterizar la influencia de El Niño del Pacífico Central y Oriental en las lluvias de verano del hemisferio Sur a través de sus teleconexiones atmosféricas. Adicionalmente, también se caracteriza la contribución de la variación espacial de la Zona de Convergencia del Pacífico Sur (ZCPS) y la Zona de Convergencia Intertropical (ZCIT). Se espera que este trabajo contribuya en el mejoramiento de los sistemas de pronósticos para mitigar los impactos de las lluvias causadas por ambos tipos de El Niño.
9
documento de trabajo
Publicado 2021
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La precipitación es una de las variables más difíciles de estimar utilizando predictores de gran escala. Para el Perú, esta tarea es aún más desafiante, dada la compleja topografía de los Andes. Una posible mejora de las estimaciones se logra con el desarrollo de modelos de downscaling empírico-estadístico (ESD, por sus siglas en inglés), pero tales modelos aún son muy escasos en el país. Para abordar este problema, se propone el modelo ESD a fin de estimar la precipitación de verano (diciembre-enero-febrero [DEF]) sobre el Perú. El modelo ESD se basa en la técnica de regresión lineal múltiple para el período 1982-2016 y considera como predictores a los índices de convección del océano Pacífico ecuatorial, el océano Atlántico y las regiones convectivas. Los análisis estadísticos muestran que el modelo ESD puede reproducir las anomalías de las precipitaciones ob...
10
artículo
Publicado 2023
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The Mantaro River Basin is one of the most important regions in the central Peruvian Andes in terms of hydropower generation and agricultural production. Contributions to better understanding of the climate and hydrological dynamics are vital for this region and constitute key information to support regional water security and socioeconomic resilience. This study presents eight years of monthly isotopic precipitation information (δ¹⁸O, Dxs) collected in the Mantaro River Basin. The isotopic signals were evaluated in terms of moisture sources, including local and regional climatic parameters, to interpret their variability at monthly and interannual timescales. It is proposed that the degree of rainout upstream and the transport history of air masses, also related to regional atmospheric features, are the main factors influencing the δ¹⁸O variability. Moreover, significant correla...
11
artículo
Publicado 2021
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Precipitation is one of the most difficult variables to estimate using large scale predictors. Over South America (SA), this task is even more challenging, given the complex topography of the Andes. Empirical Statistical Downscaling (ESD) models can be used for this purpose, but such models, applicable for all of SA, have not yet been developed. To address this issue, we construct an ESD model based on multiple linear regression techniques for the period 1982-2016 that is based on large-scale circulation indices representing tropical Pacific, Atlantic, and South American climate variability, to estimate austral summer (DJF) precipitation over SA. Statistical analyses show that the ESD model can reproduce observed precipitation anomalies over the tropical Andes (Ecuador, Colombia, Peru, and Bolivia), the eastern equatorial Amazon basin, and the central part of the western Argentinian Ande...
12
documento de trabajo
Publicado 2024
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La cuenca del río Mantaro es una región de alta importancia económica en Perú. Especialmente, contribuye de forma significativa a la producción de energía hidroeléctrica y agrícola que abastece a la capital, Lima. Por ello, es crucial comprender los procesos atmosféricos, climáticos e hidrológicos para abordar eficazmente los desafíos relacionados con la gestión del agua y el cambio climático en esta región. El presente estudio analiza datos isotópicos (δ¹⁸O, Dxs) de precipitación recopilados en la cuenca del río Mantaro mediante las estaciones de Marcapomacocha (enero de 2006-marzo de 2012) y Huayao (diciembre de 2016-abril de 2018). Dicha información se evaluó en términos de fuentes de humedad y parámetros climáticos locales y regionales para su interpretación a escala temporal mensual y anual. Asimismo, se analizaron dos eventos climáticos extremos: la seq...
13
artículo
Publicado 2018
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The climatological and large‐scale characteristics of the extreme cold events (ECEs) in the central Peruvian Andes (Mantaro basin (MB)) during austral summer (January–March) are examined using reanalysis, gridded and in situ surface minimum temperature (Tmin) data for the 1979–2010 period. To describe the influence of the Madden–Julian Oscillation (MJO) on ECEs in the MB, two ECE groups are defined on the basis of the sign of the outgoing long‐wave radiation (OLR) anomalies in the MJO band (30–100 days, 0–9 eastward) at 12.5°S, 75°W. Type‐1 ECEs occur during the suppressed convection phase of the MJO (OLR anomalies ≥+2 W/m2) while Type‐2 ECEs occur during the enhanced convection phase of the MJO (OLR anomalies ≤−2 W/m2). ECEs in the MB are associated with the advection of cold and dry air along the east of the Andes through equatorward propagation of extratrop...
14
artículo
Publicado 2018
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The climatological and large-scale characteristics of the extreme cold events (ECEs) in the central Peruvian Andes (Mantaro basin (MB)) during austral summer (January–March) are examined using reanalysis, gridded and in situ surface minimum temperature (Tmin) data for the 1979–2010 period.
15
artículo
Publicado 2025
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Lowest events in Lake Titicaca’s water level (LTWL) significantly impact local ecosystems and the drinking water supply in Peru and Bolivia. However, the hydroclimatic mechanisms driving extreme lake-level lowstands remain poorly understood. To investigate these low lake-level events, we analyzed detrended monthly LTWL anomalies, sea Surface temperature (SST) datasets covering the period 1921–2023. ERA5 reanalysis covers the period 1940–2023. A multiple linear regression model was developed to compute detrended LTWL anomalies, excluding multidecadal and residual components. Interdecadal Pacific Oscillation (IPO) and Pacific Decadal Oscillation (PDO) índices were also analyzed for the same period. Results indicate that 25% of all LTWL minima events have a short duration of <5 months, while the remaining 75% of all events have a long duration of more than 9 months, respectively. All...
16
documento de trabajo
Publicado 2018
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El presente estudio tiene por objetivo caracterizar los patrones de anomalías de Tmin cuando coinciden la MJO y las diferentes fases del ENOS durante el verano. La principal expectativa de este estudio es proporcionar material para la mejora del sistema de monitoreo de eventos fríos extremos en los Andes centrales peruanos y así reducir los daños en los cultivos locales.
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artículo
Filiación institucional de autor: Alejo Cochachín Rapre /Autoridad Nacional del Agua - Unidad de Glaciología y Recursos Hídricos (ANA-UGRH), Huaraz, Peru
18
artículo
Publicado 2013
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Original abstract: The aim of this paper is to provide the community with a comprehensive overview of the studies of glaciers in the tropical Andes conducted in recent decades leading to the current status of the glaciers in the context of climate change. In terms of changes in surface area and length, we show that the glacier retreat in the tropical Andes over the last three decades is unprecedented since the maximum extension of the Little Ice Age (LIA, mid-17th–early 18th century). In terms of changes in mass balance, although there have been some sporadic gains on several glaciers, we show that the trend has been quite negative over the past 50 yr, with a mean mass balance deficit for glaciers in the tropical Andes that is slightly more negative than the one computed on a global scale. A break point in the trend appeared in the late 1970s with mean annual mass balance per year decr...
19
artículo
Publicado 2024
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A better understanding of the relative roles of internal climate variability and external contributions, from both natural (solar, volcanic) and anthropogenic greenhouse gas forcing, is important to better project future hydrologic changes. Changes in the evaporative demand play a central role in this context, particularly in tropical areas characterized by high precipitation seasonality, such as the tropical savannah and semi-desertic biomes. Here we present a set of geochemical proxies in speleothems from a well-ventilated cave located in central-eastern Brazil which shows that the evaporative demand is no longer being met by precipitation, leading to a hydrological deficit. A marked change in the hydrologic balance in central-eastern Brazil, caused by a severe warming trend, can be identified, starting in the 1970s. Our findings show that the current aridity has no analog over the las...
