Browsing by Author "Vuille, Mathias"
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Item Restricted Climatology of extreme cold events in the Central Peruvian Andes during austral Summer: Origin, types and teleconnections(Wiley, 2018-10) Sulca Jota, Juan Carlos; Vuille, Mathias; Roundy, Paul; Takahashi, Ken; Espinoza, Jhan Carlo; Silva Vidal, Yamina; Trasmonte Soto, Grace Liliam; Zubieta Barragán, RicardoThe 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 basis of the sign of the OLR anomalies in the MJO band (30‐100 days, 0‐9 eastward) at (75°W, 12.5°S). 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 extratropical Rossby wave trains (ERWTs). This cold advection weakens the Bolivian High‐Nordeste Low (BH‐NL) system over South America (SA) at upper‐tropospheric levels. The MJO is an important driver of ECEs in the MB, favoring the cold advection along the Andes during specific MJO phases. 59% of Type‐1 ECE's and 86% of Type‐2 ECE's occur in MJO Phases 7‐2. Type‐1 and 2 ECE's feature a weakened BH over SA at upper‐tropospheric levels. For Type‐1, ERWTs emanate from southeastern Africa in MJO Phases 8‐1 while ERWTs are strenghened when crossing the subtropical southern Pacific Ocean during MJO Phases 2 and 7. With respect to Type‐2, MJO Phases 7‐2 feature circumpolar Rossby wave trains propagation toward SA. Ultimately, MJO Phases 7‐2 induce negative Tmin anomalies over MB, while MJO Phases 3‐6 induce positive Tmin anomalies. El Niño and La Niña strengthen negative Tmin anomalies over the MB during MJO Phases 7‐8 while they weaken positive Tmin anomalies over the MB during MJO Phases 3‐6.Item Restricted Empirical–Statistical Downscaling of austral summer precipitation over South America, with a focus on the central Peruvian Andes and the equatorial Amazon basin(American Meteorological Society, 2021-01-12) Sulca Jota, Juan Carlos; Vuille, Mathias; Timm, Oliver Elison; Dong, Bo; Zubieta Barragán, RicardoPrecipitation 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 Andes. On a smaller scale, the ESD model also shows good results over the western Cordillera of the Peruvian Andes. The ESD model reproduces anomalously dry conditions over the eastern equatorial Amazon and the wet conditions over Southeastern South America (SESA) during the three extreme El Niño’s 1982/83, 1997/98, and 2015/16. However, it overestimates the observed intensities over SESA. For the central Peruvian Andes as a case study, results further show that the ESD model can correctly reproduce DJF precipitation anomalies over the entire Mantaro basin during the three extreme El Niño episodes. Moreover, multiple experiments with varying predictor combinations of the ESD model corroborate the hypothesis that the interaction between the South Atlantic Convergence Zone (SACZ) and the equatorial Atlantic Ocean provoked the Amazon drought in 2015/16.Item Open Access Fuentes de humedad y variabilidad de la señal isotópica δ¹⁸O de precipitación en los Andes Centrales de Perú, caso de estudio: la cuenca del río Mantaro(Instituto Geofísico del Perú, 2024-03) Romero, Carol; Apaéstegui Campos, James Emiliano; Vuille, Mathias; Sulca Jota, Juan Carlos; Ampuero, AngelaLa 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 sequía de 2010 y el Niño Costero de 2017, con el fin de entender la influencia de la circulación atmosférica regional con relación a la señal geoquímica. De los resultados obtenidos, se infiere que la variación de la señal isotópica δ¹⁸O está altamente influenciada por el historial de transporte de las masas de aire y el nivel de precipitaciones aguas arriba. También se observaron correlaciones significativas con la cantidad de precipitación y la humedad relativa, lo que implica que los procesos locales también tienen una influencia importante en la variabilidad de la señal isotópica δ¹⁸O. Estos resultados proporcionan una base para estudios hidroclimáticos y reconstrucciones paleoclimáticas en la cuenca del río Mantaro.Item Open Access Impactos de la concurrencia de la Oscilación Madden-Julian (MJO) y de El Niño-Oscilación Sur (ENOS) en las temperaturas mínimas de verano en los Andes centrales del Perú(Instituto Geofísico del Perú, 2018-11) Sulca Jota, Juan Carlos; Vuille, Mathias; Roundy, Paul; Takahashi, Ken; Espinoza, Jhan Carlo; Silva Vidal, Yamina; Trasmonte, Grace; Zubieta Barragán, RicardoEl 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.Item Open Access Impactos de los diferentes tipos de El Niño (Central y del Este) y de las regiones convectivas del Pacífico en las lluvias de verano en el Perú(Instituto Geofísico del Perú, 2018-07) Sulca Jota, Juan Carlos; Takahashi, Ken; Vuille, Mathias; Espinoza, Jhan Carlo; Lavado Casimiro, WaldoEl 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.Item Restricted Impacts of different ENSO flavors and tropical Pacific convection variability (ITCZ, SPCZ) on austral summer rainfall in South America, with a focus on Peru(Royal Meteorological Society, 2018-01) Sulca Jota, Juan Carlos; Takahashi, Ken; Espinoza, Jhan Carlo; Vuille, Mathias; Lavado-Casimiro, WaldoEl 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. Positive C induces dry anomalies along the tropical Andes and northern South America (NSA), while wet anomalies prevail over southeastern South America (SESA). Moreover, it produces wet conditions in the northwestern Peruvian Amazon. In contrast, positive E enhances wet conditions along the coasts of Ecuador and northern Peru associated with the southward displacement of the eastern Pacific ITCZ and induces dry conditions in Altiplano, Amazon basin, and northeastern Brazil (NEB). Both El Niño Southern Oscillation (ENSO) indices are associated with weakened upper‐level easterly flow over Peru, but it is more restricted to the central and southern Peruvian Andes with positive E. Both SPCZ indices, the zonal position of the SPCZ and its latitudinal displacement, suppress rainfall along western Peruvian Andes when are positive, but the latter also inhibits rainfall over the Bolivian Altiplano. They are also linked to upper‐level westerly wind anomalies overall of Peru, but these anomalies do not extend as far south in the first. The southward displacement of the eastern Pacific ITCZ also induces wet anomalies in SESA while dry anomalies prevail over NEB, the western Amazon basin, and Bolivia. Oppositely, the southward displacement of the central Pacific ITCZ induces dry anomalies in NEB and along the northern coast of Peru; while wet anomalies occur mainly in eastern Brazil, Paraguay, and Bolivia through an enhancement of the low level jet.Item Open Access Influencia de ENOS en los eventos extremos de precipitación en los Andes centrales peruanos durante el verano(Instituto Geofísico del Perú, 2019-01) Sulca Jota, Juan Carlos; Vuille, Mathias; Silva Vidal, Yamina; Takahashi, KenEl 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.Item Open Access Interdecadal variability of the austral summer precipitation over the Central Andes(Frontiers Media, 2022-09-12) Sulca Jota, Juan Carlos; Vuille, Mathias; Dong, BoThe 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 between the northern Bolivian and the Chilean Altiplano. REOF2 also features a precipitation dipole, with highest negative loading over the southern Peruvian Andes. The REOF1 positive phase is associated with moisture transport from the lowlands toward the Bolivian Altiplano, induced by upper-level easterly wind anomalies over the Central Andes. At the same time conditions tend to be dry over the southern Peruvian Andes. The positive phase of REOF2 is related to weakened moisture transport, induced by upper-level westerly wind anomalies over Peru. The IPO warm phase induces significant dry anomalies over the Bolivian Altiplano, albeit weaker than during the IN4 warm phase, via upper-level westerly wind anomalies over the Central Andes. No significant relationship was found between Central Andean precipitation and the AMO on interdecadal timescales.Item Restricted Investigating δ¹³C values in stalagmites from tropical South America for the last two millennia(Elsevier, 2021-03-01) Novello, Valdir Felipe; William da Cruz, Francisco; Vuille, Mathias; Pereira Silveira Campos, José Leandro; Stríkis, Nicolás Misailidis; Apaéstegui Campos, James Emiliano; Moquet, Jean Sebastien; Azevedo, Vitor; Ampuero, Angela; Utida, Giselle; Wang, Xianfeng; Paula-Santos, Gustavo Macedo; Jaqueto, Plinio; Ruiz Pessenda, Luiz Carlos; Breecker, Daniel O.; Karmann, IvoDue to the many factors controlling δ¹³C values in stalagmites, complicating their paleoclimatic and paleoenvironmental interpretation, most studies do not present δ¹³C values, but instead focus mainly on δ¹⁸O values. This is also the case for most cave studies from tropical South America, where many new δ¹⁸O stalagmite records covering the last millennia were recently published. Here, we review the δ¹³C values in stalagmites, investigating the influence on this proxy of local hydroclimate, altitude, temperature and vegetation types, by employing a new dataset composed of published and unpublished carbon isotope records from various sites in tropical South America. The main factors influencing δ¹³C values are associated with the local hydroclimate, followed by minor effects from temperature. Most of the isotopic records show a significant correlation between the δ¹³C and δ¹⁸O values, indicating a close relationship between local hydroclimate and atmospheric convective processes related to the South American Monsoon System.Item Open Access Modelo de downscaling empírico-estadístico para las lluvias de verano del Perú(Instituto Geofísico del Perú, 2021-01) Sulca Jota, Juan Carlos; Vuille, Mathias; Elison Timm, Oliver; Dong, Bo; Zubieta Barragán, RicardoLa 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 observadas en la cordillera occidental de los Andes peruanos. No obstante, el modelo ESD no reproduce adecuadamente las precipitaciones de verano sobre la costa norte del Perú y en gran parte de la Amazonía peruana. Esto está, probablemente, asociado al limitado número de estaciones meteorológicas en muchas regiones del Perú, al corto periodo de calibración del modelo ESD y, también, a los forzantes locales que no fueron incluidos en la construcción del modelo ESD. En particular, el modelo ESD reproduce correctamente las anomalías de la precipitación de DEF en toda la cuenca del Mantaro (CM), que se localiza en los Andes centrales del Perú, durante los tres episodios extremos de El Niño. Por ejemplo, las anomalías negativas (condiciones secas) sobre la CM en los episodios El Niño de 1982/83 y 2015/16 y las anomalías positivas (condiciones húmedas) predominantes durante El Niño 1997/98.Item Open Access Modern anthropogenic drought in Central Brazil unprecedented during last 700 years(Nature Research, 2024-02-26) Misailidis Stríkis, Nicolas; Silva Melo Buarque, Plácido Fabrício; Cruz, Francisco William; Bernal, Juan Pablo; Vuille, Mathias; Tejedor, Ernesto; Simões Santos, Matheus; Harumi Shimizu, Marília; Ampuero, Angela; Du, Wenjing; Sampaio, Gilvan; Reis Sales, Hamilton dos; Campos, José Leandro; Toshie Kayano, Mary; Apaéstegui Campos, James Emiliano; Fu, Roger R.; Cheng, Hai; Edwards, R. Lawrence; Chavez Mayta, Victor; Silva Francischini, Danielle da; Zezzi Arruda, Marco Aurélio; Felipe Novello, ValdirA 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 last 720 years. A detection and attribution study indicates that this trend is mostly driven by anthropogenic forcing and cannot be explained by natural factors alone. These results reinforce the premise of a severe long-term drought in the subtropics of eastern South America that will likely be further exacerbated in the future given its apparent connection to increased greenhouse gas emissions.Item Open Access Modos interdecenales de las precipitaciones de los Andes centrales en el siglo XX(Instituto Geofísico del Perú, 2023-04) Sulca Jota, Juan Carlos; Vuille, Mathias; Dong, BoLa 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 con valores negativos altos sobre los Andes peruanos del sur. La fase positiva de REOF1 está asociada al transporte de humedad proveniente de la Amazonía hacia los Andes bolivianos norte por el fortalecimiento de vientos del este sobre los Andes centrales en la alta tropósfera que incrementa la precipitación sobre el Altiplano boliviano y la parte norte de los Andes chilenos y argentinos (17-25° S). En contraste, la fase positiva de REOF2, con menor precipitación en los Andes centrales peruanos, está asociada con un debilitamiento del transporte de humedad del este causado por los vientos anómalos del oeste sobre el Perú en los niveles troposféricos altos. La fase caliente de la OIP se asocia a precipitaciones reducidas sobre los Andes centrales, aunque se encontró que el IN4 presenta una señal más fuerte que la OIP debido a vientos anómalos del oeste más intensos sobre los Andes centrales en la alta tropósfera. No se encontró una relación lineal significativa de la OMA con las precipitaciones de los Andes centrales.Item Open Access Moisture Sources and Rainfall δ¹⁸O Variability over the Central Andes of Peru—A Case Study from the Mantaro River Basin(MDPI, 2023-05-15) Apaéstegui Campos, James Emiliano; Romero, Carol; Vuille, Mathias; Sulca Jota, Juan Carlos; Ampuero, AngelaThe 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 correlations with precipitation amount and relative humidity imply that local processes in this region of the Andes also exert important control over isotopic variability. Two extreme regional climate events (the 2010 drought and the 2017 coastal El Niño) were evaluated to determine how regional atmospheric circulation affects the rainfall isotope variability. Based on these results, recommendations for hydroclimate studies and paleoclimate reconstructions are proposed in the context of the Mantaro River Basin. This study intends to encourage new applications considering geochemical evidence for hydrological studies over the central Andean region.Item Restricted Precipitation changes over the eastern Bolivian Andes inferred from speleothem (δ¹⁸O) records for the last 1400 years(Elsevier, 2018-07-15) Apaéstegui Campos, James Emiliano; William Cruz, Francisco; Vuille, Mathias; Fohlmeister, Jens; Espinoza, Jhan Carlo; Sifeddine, Abdelfettah; Strikis, Nicolas; Guyot, Jean Loup; Ventura, Roberto; Cheng, Hai; Edwards, R. LawrenceHere we present high-resolution δ¹⁸ records obtained from speleothems collected in the eastern Bolivian Andes. The stable isotope records are related to the regional- to large-scale atmospheric circulation over South America and allow interpreting changes in δ¹⁸ during the last 1400 yr as a function of changes in precipitation regimes over the southern tropical Andes. Two distinct phases with more negative δ¹⁸ values, interpreted as periods of increased convective activity over the eastern Andean Cordillera in Bolivia are observed concomitantly with periods of global climate anomalies during the last millennium, such as the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) respectively. Changes in the Bolivian δ¹⁸ record during the LIA are apparently related to a southward displacement of the Intertropical Convergence Zone (ITCZ), which acts as a main moisture driver to intensify convection over the tropical continent. During the MCA, however, the increased convective activity observed in the Bolivian record is likely the result of a different mechanism, which implies moisture sourced mainly from the southern tropical Atlantic. This interpretation is consistent with paleoclimate records further to the north in the tropical Andes that show progressively drier conditions during this time period, indicating a more northerly position of the ITCZ. The transition period between the MCA and the LIA shows a slight tendency toward increased δ¹⁸ values, indicating weakened convective activity. Our results also reveal a non-stationary anti-phased behavior between the δ¹⁸ reconstructions from Bolivia and northeastern Brazil that confirms a continental-scale east–west teleconnection across South America during the LIA.Item Open Access Teleconnections between the Peruvian central Andes and northeast Brazil during extreme rainfall events in austral summer(American Meteorological Society, 2016-02) Sulca Jota, Juan Carlos; Vuille, Mathias; Silva Vidal, Yamina; Takahashi, KenExtreme 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 Amazon during dry events, while wet events are characterized by opposite conditions. Yet, while easterly wind anomalies appear to be a prerequisite for heavy precipitation events in the region, they are not a sufficient forcing, as dry days can still occur during such periods. Dry spells in the Peruvian Andes appear to be linked to weakened convective activity over the western tropical Pacific, consistent with the previously documented El Niño influence over the region. Extreme dry and wet spells in northeastern Brazil only show a weak link to precipitation anomalies of the opposite sign over Peru but are strongly coupled with changes in the position and strength of the Nordeste low and the South Atlantic convergence zone.