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Item Restricted A framework for the science contribution in climate adaptation: experiences from science-policy processes in the Andes(Elsevier, 2015-03) Huggel, Christian; Scheel, Marlene; Albrecht, Franziska; Andres, Norina; Calanca, Pierluigi; Jurt, Christine; Khabarov, Nikolay; Mira-Salama, Daniel; Rohrer, Mario; Salzmann, Nadine; Silva Vidal, Yamina; Silvestre, Elizabeth; Vicuña, Luis; Zappa, MassimilianoAs significant impacts of climate change are increasingly considered unavoidable, adaptation has become a policy priority. It is generally agreed that science is important for the adaptation process but specific guidance on how and to what degree science should contribute and be embedded in this process is still limited which is at odds with the high demand for science contributions to climate adaptation by international organizations, national governments and others. Here we present and analyze experiences from the tropical Andes based on a recent science-policy process on the national and supra-national government level. During this process a framework for the science contribution in climate adaptation has been developed; it consists of three stages, including (1) the framing and problem definition, (2) the scientific assessment of climate, impacts, vulnerabilities and risks, and (3) the evaluation of adaptation options and their implementation. A large amount of methods has been analyzed for stage (2), and a number of major climate adaptation projects in the region assessed for (3). Our study underlines the importance of joint problem framing among various scientific and non-scientific actors, definition of socio-environmental systems, time frames, and a more intense interaction of social and physical climate and impact sciences. Scientifically, the scarcity of environmental, social and economic data in regions like the Andes continue to represent a limitation to adaptation, and further investments into coordinated socio-environmental monitoring, data availability and sharing are essential.Item Open Access A global ocean oxygen database and atlas for assessing and predicting deoxygenation and ocean health in the open and coastal ocean(Frontiers Media, 2021-12-21) Grégoire, Marilaure; Garçon, Véronique; Garcia, Hernan; Breitburg, Denise; Isensee, Kirsten; Oschlies, Andreas; Telszewski, Maciej; Barth, Alexander; Bittig, Henry C.; Carstensen, Jacob; Carval, Thierry; Chai, Fei; Chavez, Francisco; Conley, Daniel; Coppola, Laurent; Crowe, Sean; Currie, Kim; Dai, Minhan; Deflandre, Bruno; Dewitte, Boris; Diaz, Robert; Garcia-Robledo, Emilio; Gilbert, Denis; Giorgetti, Alessandra; Glud, Ronnie; Gutierrez, Dimitri; Hosoda, Shigeki; Ishii, Masao; Jacinto, Gil; Langdon, Chris; Lauvset, Siv K.; Levin, Lisa A.; Limburg, Karin E.; Mehrtens, Hela; Montes Torres, Ivonne; Naqvi, Wajih; Paulmier, Aurélien; Pfeil, Benjamin; Pitcher, Grant; Pouliquen, Sylvie; Rabalais, Nancy; Rabouille, Christophe; Recape, Virginie; Roman, Michaël; Rose, Kenneth; Rudnick, Daniel; Rummer, Jodie; Schmechtig, Catherine; Schmidtko, Sunke; Seibel, Brad; Slomp, Caroline; Sumalia, U. Rashid; Tanhua, Toste; Thierry, Virginie; Uchida, Hiroshi; Wanninkhof, Rik; Yasuhara, MoriakiIn this paper, we outline the need for a coordinated international effort toward the building of an open-access Global Ocean Oxygen Database and ATlas (GO₂DAT) complying with the FAIR principles (Findable, Accessible, Interoperable, and Reusable). GO₂DAT will combine data from the coastal and open ocean, as measured by the chemical Winkler titration method or by sensors (e.g., optodes, electrodes) from Eulerian and Lagrangian platforms (e.g., ships, moorings, profiling floats, gliders, ships of opportunities, marine mammals, cabled observatories). GO₂DAT will further adopt a community-agreed, fully documented metadata format and a consistent quality control (QC) procedure and quality flagging (QF) system. GO₂DAT will serve to support the development of advanced data analysis and biogeochemical models for improving our mapping, understanding and forecasting capabilities for ocean O₂ changes and deoxygenation trends. It will offer the opportunity to develop quality-controlled data synthesis products with unprecedented spatial (vertical and horizontal) and temporal (sub-seasonal to multi-decadal) resolution. These products will support model assessment, improvement and evaluation as well as the development of climate and ocean health indicators. They will further support the decision-making processes associated with the emerging blue economy, the conservation of marine resources and their associated ecosystem services and the development of management tools required by a diverse community of users (e.g., environmental agencies, aquaculture, and fishing sectors). A better knowledge base of the spatial and temporal variations of marine O₂ will improve our understanding of the ocean O₂ budget, and allow better quantification of the Earth’s carbon and heat budgets. With the ever-increasing need to protect and sustainably manage ocean services, GO₂DAT will allow scientists to fully harness the increasing volumes of O₂ data already delivered by the expanding global ocean observing system and enable smooth incorporation of much higher quantities of data from autonomous platforms in the open ocean and coastal areas into comprehensive data products in the years to come. This paper aims at engaging the community (e.g., scientists, data managers, policy makers, service users) toward the development of GO₂DAT within the framework of the UN Global Ocean Oxygen Decade (GOOD) program recently endorsed by IOC-UNESCO. A roadmap toward GO₂DAT is proposed highlighting the efforts needed (e.g., in terms of human resources).Item Restricted A multiple linear regression model for the prediction of summer rainfall in the northwestern Peruvian Amazon using large-scale indices(Springer, 2024-01-02) Sulca Jota, Juan Carlos; Takahashi, Ken; Espinoza, Jhan-Carlo; Tacza, José; Zubieta Barragán, Ricardo; Mosquera Vásquez, Kobi Alberto; Apaéstegui Campos, James EmilianoThe northwestern Peruvian Amazon (NWPA) basin (78.4–75.8° W, 7.9–5.4° S) is an important region for coffee and rice production in Peru. Currently, no prediction models are available for estimating rainfall in advance during the wet season (January–February–March, JFM). Hence, we developed multiple linear regression (MLR) models using predictors derived from sea surface temperature (SST) indices of the Pacific, Atlantic, and Indian Oceans, including central El Niño (C), eastern El Niño (E), tropical South Atlantic (tSATL), tropical North Atlantic (tNATL), extratropical North Atlantic (eNATL), and Indian Ocean basin-wide with E and C removed (IOBW*) indices. Additionally, we utilized large-scale convection indices, namely, the eastern Pacific intertropical convergence zone (ITCZe) and South American Monsoon System (SAMSi) indices, for the 1981–2018 period. Rainfall in the lowland NWPA exhibits a bimodal annual cycle, whereas rainfall in the highland NWPA exhibits a unimodal annual cycle. The MLR model can be used to accurately capture the interannual variability during the wet season in the highland NWPA by utilizing predictors derived from the C and SAMSi indices. In contrast, regarding rainfall in the lowland NWPA, the Pacific SST variability, SAMS and tropical North Atlantic index were relevant. For long lead times, the MLR model provided reliable forecasts of JFM rainfall anomalies in the highlands (R3, approximately 2700 m asl) as these regions are governed by Pacific variability. However, the MLR model exhibited limitations in accurately estimating the wettest JFM season in the highlands due to the absence of a predictor for the amplified effect of the Madden–Julian Oscillation on rainfall.Item Restricted A reassessment of the suspended sediment load in the Madeira River basin from the Andes of Peru and Bolivia to the Amazon River in Brazil, based on 10 years of data from the HYBAM monitoring programme(Elsevier, 2017-10) Vauchel, Phillippe; Santini, William; Guyot, Jean Loup; Moquet, Jean Sébastien; Martínez, Jean Michel; Espinoza, Jhan Carlo; Baby, Patrice; Fuertes, Oscar; Noriega, Luis; Puita, Oscar; Sondag, Francis; Fraizy, Pascal; Armijos Cardenas, Elisa Natalia; Cochonneau, Gérard; Timouk, Franck; Olivera, Eurides de; Filizola, Naziano; Molina, Jorge; Ronchail, JosyaneThe Madeira River is the second largest tributary of the Amazon River. It contributes approximately 13% of the Amazon River flow and it may contribute up to 50% of its sediment discharge to the Atlantic Ocean. Until now, the suspended sediment load of the Madeira River was not well known and was estimated in a broad range from 240 to 715 Mt yr⁻¹. Since 2002, the HYBAM international network developed a new monitoring programme specially designed to provide more reliable data than in previous intents. It is based on the continuous monitoring of a set of 11 gauging stations in the Madeira River watershed from the Andes piedmont to the confluence with the Amazon River, and discrete sampling of the suspended sediment concentration every 7 or 10 days. This paper presents the results of the suspended sediment data obtained in the Madeira drainage basin during 2002–2011. The Madeira River suspended sediment load is estimated at 430 Mt yr⁻¹ near its confluence with the Amazon River. The average production of the Madeira River Andean catchment is estimated at 640 Mt yr⁻¹ (±30%), the corresponding sediment yield for the Andes is estimated at 3000 t km⁻² yr⁻¹ (±30%), and the average denudation rate is estimated at 1.20 mm yr⁻¹ (±30%). Contrary to previous results that had mentioned high sedimentation rates in the Beni River floodplain, we detected no measurable sedimentation process in this part of the basin. On the Mamoré River basin, we observed heavy sediment deposition of approximately 210 Mt yr⁻¹ that seem to confirm previous studies. But while these studies mentioned heavy sedimentation in the floodplain, we showed that sediment deposition occurred mainly in the Andean piedmont and immediate foreland in rivers (Parapeti, Grande, Pirai, Yapacani, Chimoré, Chaparé, Secure, Maniqui) with discharges that are not sufficiently large to transport their sediment load downstream in the lowlands.Item Restricted A theoretical model of strong and moderate El Niño regimes(Springer, 2019-06-01) Takahashi, Ken; Karamperidou, Christina; Dewitte, BorisThe existence of two regimes for El Niño (EN) events, moderate and strong, has been previously shown in the GFDL CM2.1 climate model and also suggested in observations. The two regimes have been proposed to originate from the nonlinearity in the Bjerknes feedback, associated with a threshold in sea surface temperature (\(T_c\)) that needs to be exceeded for deep atmospheric convection to occur in the eastern Pacific. However, although the recent 2015–16 EN event provides a new data point consistent with the sparse strong EN regime, it is not enough to statistically reject the null hypothesis of a unimodal distribution based on observations alone. Nevertheless, we consider the possibility suggestive enough to explore it with a simple theoretical model based on the nonlinear Bjerknes feedback. In this study, we implemented this nonlinear mechanism in the recharge-discharge (RD) ENSO model and show that it is sufficient to produce the two EN regimes, i.e. a bimodal distribution in peak surface temperature (T) during EN events. The only modification introduced to the original RD model is that the net damping is suppressed when T exceeds \(T_c\), resulting in a weak nonlinearity in the system. Due to the damping, the model is globally stable and it requires stochastic forcing to maintain the variability. The sustained low-frequency component of the stochastic forcing plays a key role for the onset of strong EN events (i.e. for \(T>T_c\)), at least as important as the precursor positive heat content anomaly (h). High-frequency forcing helps some EN events to exceed \(T_c\), increasing the number of strong events, but the rectification effect is small and the overall number of EN events is little affected by this forcing. Using the Fokker–Planck equation, we show how the bimodal probability distribution of EN events arises from the nonlinear Bjerknes feedback and also propose that the increase in the net feedback with increasing T is a necessary condition for bimodality in the RD model. We also show that the damping strength determines both the adjustment time-scale and equilibrium value of the ensemble spread associated with the stochastic forcing.Item Open Access Algunos apuntes históricos adicionales sobre la cronología de El Niño(Instituto Frances de Estudios Andinos, 1993) Mabres, Antonio; Woodman Pollitt, Ronald Francisco; Zeta, RosaEs necesario continuar haciendo esfuerzos para establecer un registro homogéneo y lo más completo y confiable posible de los eventos del fenómeno ENSO. La región de Piura tiene una alta sensibilidad al fenómeno, cuya presencia da lugar siempre a las abundantes lluvias. Por esto, las fuentes históricas provenientes de esta región son muy importantes. Además complementarán los estudios dendrocronólogicos que se realizan también en la región. Se dan nuevas fuentes históricas sobre las lluvias en Piura. La más interesante es del periódico "El Amigo del Pueblo", del año 1906, que recoge datos a año de 1791 a 1906. Se observa una notable concordancia con la cronología de Eguiguren que recogió Woodman (1985) y que se amplía con dichas fuentes. En cambio, hay algunas discrepancias con la relación de eventos fuertes y medianos que dan Quinn et al. (1987). Se señalan algunos de los intervalos de años (y en años singulares) extremadamente secos en los últimos 200 años.Item Open Access Análisis del pronóstico del Fenómeno de El Niño evacuado por NCEP/NOAA el 03 de diciembre de 1997: impacto sobre las lluvias en la costa norte del país(Instituto Geofísico del Perú, 1997-12-08) Woodman Pollitt, Ronald FranciscoA comienzos de Diciembre de los corrientes la National Prediction Environmental Center de la NOAA (NCEP/NOAA http://nic.fb4.noaa.gov/research/climate.html) evacuó los resultados de su última corrida ( 3 de Dic. ) de su modelo acoplado océano-atmósfera (CMP12), con los pronósticos de la temperatura del mar del Pacífico Ecuatorial para los próximos 12 meses. Los valores de la temperatura mas cercanas a las costas de Paita y Chicama evaluadas por el modelo han sido usados para pronosticar la intensidad de las futuras precipitaciones, específicamente en la ciudad de Piura. Las lluvias en la ciudad de Piura se pueden usar como índice de las lluvias en la costa-norte del país, pero con las debidas consideraciones a las gradientes tan pronunciadas en la temperatura del mar -y las correspondientes precipitaciones -, al acercarse a las regiones fronterizas con el Ecuador y las zonas montañosas. Se ha usado Piura por su largo registro metereológico, el cual permite hacer comparaciones con años pasados.Item Open Access Analysis of extreme meteorological events in the central Andes of Peru using a set of specialized instruments(MDPI, 2021-03-21) Flores Rojas, José Luis; Silva Vidal, Yamina; Suárez Salas, Luis; Estevan, René; Valdivia Prado, Jairo Michael; Saavedra Huanca, Miguel; Giráldez, Lucy; Piñas-Laura, Manuel; Scipión, Danny; Milla, Marco; Kumar, Shailendra; Martínez Castro, DanielA set of instruments to measure several physical, microphysical, and radiative properties of the atmosphere and clouds are essential to identify, understand and, subsequently, forecast and prevent the effects of extreme meteorological events, such as severe rainfall, hailstorms, frost events and high pollution events, that can occur with some regularity in the central Andes of Peru. However, like many other Latin American countries, Peru lacks an adequate network of meteorological stations to identify and analyze extreme meteorological events. To partially remedy this deficiency, the Geophysical Institute of Peru has installed a set of specialized sensors (LAMAR) on the Huancayo observatory (12.04º S, 75.32º W, 3350 m ASL), located in the Mantaro river basin, which is a part of the central Andes of Peru, especially in agricultural areas. LAMAR consists of a set of sensors that are used to measure the main atmosphere and soil variables located in a 30-meter-high tower. It also has a set of high-quality radiation sensors (BSRN station) that helps measure the components of short-wave (SW) (global, diffuse, direct and reflected) and long-wave (LW) (emitted and incident) irradiance mounted in a 6-meter-high tower. Moreover, to analyze the microphysics properties of clouds and rainfall, LAMAR includes a set of profiler radars: A Ka-band cloud profiler (MIRA-35c), a UHF wind profiler (CLAIRE), and a VHF wind profiler (BLTR), along with two disdrometers (PARSIVEL2) and two rain gauges pluviometers. The present study performs a detailed dynamic and energetic analysis of two extreme rainfall events, two intense frost events, and three high-pollution events occurring on the Huancayo observatory between 2018 and 2019...Item Open Access Analysis of possible triggering mechanisms of severe thunderstorms in the Tropical Central Andes of Peru, Mantaro Valley(MDPI, 2019-06-01) Flores Rojas, José Luis; Moya Álvarez, Aldo Saturnino; Kumar, Shailendra; Martínez Castro, Daniel; Villalobos Puma, Elver Edmundo; Silva Vidal, YaminaThe aim of the present study is to analyze the triggering mechanisms of three thunderstorms (TSs) associated with severe rainfall, hail and lightening in the tropical central Andes of Peru, specifically above the Huancayo observatory (12.04º S, 75.32º W, 3313 m a.s.l.) located in the Mantaro valley during the spring-summer season (2015–2016). For this purpose, we used a set of in-situ pluviometric observations, satellite remote sensing data, the Compact Meteorological Ka-Band Cloud Radar (MIRA-35C), the Boundary Layer Tropospheric Radar and downscaling model simulations with the Weather Research and Forecasting (WRF) Model (resolutions: 18 km, 6 km and 2 km), and the Advance Regional Prediction System (ARPS) (resolution: 0.5 km) models in order to analyze the dynamic of the atmosphere in the synoptic, meso and local scales processes that control the occurrence of the three TS events. The results show that at synoptic scale, the TSs are characterized by the southern displacement of the South-east Pacific Subtropical Anticyclone up to latitudes higher than 35º S, by the weakening and south-eastern displacement of the Bolivian high–North east low system and by the intrusion of westerly winds along the west side of the central Andes at upper and medium levels of the atmosphere. At meso-scale, apparently, two important moisture fluxes from opposite directions are filtered through the passes along the Andes: one from the north-west and the other from the south-east directions converge and trigger the deep convection into the Mantaro valley. These moisture fluxes are generated by the intrusion of the sea-breeze from the Pacific ocean along the west of the Andes coupling with upper and middle westerly winds and by the thermally induced moisture fluxes coming from the South American low level jet at the east side of the Andes. At the local scale, there is a low-level conditional instability in the previous hours as well as during the occurrence of the TSs above the Huancayo observatory. In addition, the simulation results indicated the possibility of generation of inertial gravity waves in the Amazon basin, associated with geostrophic adjustment which transports energy and moisture into the central Andes plateau and consequently intensifies the thunderstorms above the Mantaro valley.Item Open Access Analysis of vertical flow velocity and suspended sediment concentration profiles in Tumbes River during El Niño and La Niña events. [Análisis de los perfiles verticales de velocidad de flujo y de concentración de sedimentos en suspensión medidos en el río Tumbes durante El Niño y La Niña](LACCEI, Latin American and Caribbean Consortium of Engineering Institutions, 2024-07) Mendoza Sulcaray, Renzo Dampier; Campaña Toro, Roberto Luis; Armijos Cárdenas, Elisa Natalia; Morera Julca, Sergio ByronLa región de Tumbes, ubicada en el norte de Perú, se ve afectada por los fenómenos climáticos de El Niño y La Niña. El Niño provoca una intensa precipitación, lo que resulta en altos flujos de agua y generación de sedimentos. En cambio, La Niña conlleva déficits de precipitación, resultando en flujos líquidos más bajos y cargas de sedimentos menores en comparación con El Niño. El objetivo de este estudio es analizar los perfiles verticales de velocidad de flujo y la concentración de sedimentos en suspensión medidos en la estación hidrométrica El Tigre en el río Tumbes, ubicado a 50 km río arriba del estuario del Océano Pacífico, durante los períodos de inundación en los eventos de El Niño de 2017 y La Niña de 2018. Los perfiles verticales de velocidad de flujo, medidos utilizando un medidor de corriente de efecto Doppler, se modelaron aplicando la distribución teórica de velocidad del tipo log-wake. Se ajustaron parámetros como la velocidad de corte, la distancia desde el lecho donde teóricamente la velocidad del perfil de flujo se vuelve cero y el parámetro de estela. Los perfiles verticales de concentración de sedimentos en suspensión se modelaron utilizando la distribución teórica resultante de la distribución parabólico-lineal del coeficiente de mezcla de fluidos. Se ajustaron parámetros, incluyendo el diámetro medio de los sedimentos en suspensión y la concentración de sedimentos en suspensión de referencia cerca del lecho. El estudio concluyó que los perfiles verticales de velocidad de flujo y concentración de sedimentos en suspensión registrados durante el evento de El Niño de 2017 y el evento de La Niña de 2018 coincidieron razonablemente con la distribución teórica de velocidad del tipo log-wake y la distribución teórica de concentración de sedimentos en suspensión resultante de la distribución parabólico-lineal del coeficiente de mezcla de fluidos. Utilizando los modelos ajustados, se estimó que los tamaños medios de los sedimentos en suspensión calculados para el evento de El Niño de 2017 (62 a 132 µm) fueron aproximadamente 2 veces mayores que los calculados para La Niña de 2018 (25 a 67 µm), y que las concentraciones de sedimentos en suspensión de referencia en el lecho calculadas para el evento de El Niño de 2017 (254 a 1766 mg/l) fueron aproximadamente 7 veces mayores que las calculadas para La Niña de 2018 (95 a 250 mg/l).Item Open Access Aporte cuantitativo de las fuentes de PM₁₀ y PM₂﹒₅ en sitios urbanos del Valle del Mantaro, Perú(Universidad Nacional Autónoma de México, 2020-10-30) Álvarez Tolentino, Daniel; Suárez Salas, LuisLas partículas atmosféricas (PM₁₀ y PM₂.₅) son responsables de serios problemas en la salud humana. Por ello, este estudio determina el aporte cuantitativo de las fuentes de ambos tipos de partículas en las principales ciudades del Valle del Mantaro, ubicadas en la parte central del Perú. Se analizan los datos obtenidos en la campaña de monitoreo mensual de los centros urbanos de Jauja, Concepción y Huancayo, desde julio de 2007 hasta octubre de 2008. Para el monitoreo se empleó un muestreador de bajo volumen (modelo Partisol). La composición química elemental fue obtenida por fluorescencia de rayos X y se les aplicó el análisis de componentes principales con rotación varimax y análisis de componentes principales absoluto. Los agrupamientos de los elementos químicos fueron contrastados con el factor de enriquecimiento y análisis de conglomerados jerárquico. Los resultados mostraron que las PM₁₀ y PM₂.₅ fueron significativamente mayores en Huancayo (p < 0.05), zona urbana donde se superó el Estándar de Calidad Ambiental para Aire (ECA) de la legislación peruana, para ambos tamaños de partículas. Se determinaron trazadores de fuentes naturales y antrópicas. En total se detectaron cinco fuentes de emisión para los sitios urbanos del Valle del Mantaro: polvo del suelo (Al, Ca, Si, Fe, Ti, Mn y K), quema de biomasa (Cl, Br, K), vehículos (Cu, Zn, Cl, Cr), combustible-aceite (Ni) y fundición (Pb, Zn, As y Cu), siendo el polvo del suelo la principal fuente de aporte de PM₁₀ y PM₂.₅.Item Restricted Assessing precipitation concentration in the Amazon basin from different satellite‐based data sets(Royal Meteorological Society, 2019-06-15) Zubieta Barragán, Ricardo; Saavedra Huanca, Miguel; Espinoza, Jhan Carlo; Ronchail, Josyane; Sulca Jota, Juan Carlos; Drapeau, Guillaume; Martin‐Vide, JavierDaily precipitation concentration in the Amazon basin (AB) is characterized using concentration index (CI), which is computed from HYBAM Observed Precipitation (HOP) data set, for 1980–2009 period. The ability of four satellite precipitation data sets (TMPA V7, TMPA RT, CMORPH and PERSIANN) to estimate CI is evaluated for 2001–2009 period. Our findings provide new information about the spatial irregularity of daily rainfall distribution over the AB. In addition, the spatial distribution of CI values is not completely explained by rainfall seasonality, which highlights the influence of different weather systems over the AB. The results of rainfall concentration indicate that the distribution of daily rainfall is more regular over northwest (northern Peru) and central Andes. Conversely, Roraima region and a large area of Bolivian Amazon register the highest irregularity in the daily rainfall. Bolivian Amazon also represents regions where the large percentage of total rainfall arises from extreme events (>90th percentile). Heavy rainfall episodes over Roraima region are induced by humidity influx come from Caribbean region, while heavy rainfall events over Bolivian Amazon and Andes region are induced by the northwards propagation of cold and dry air along both sides of Andes Mountains, but only propagate in all tropospheric levels for the Andes. The results also show that PERSIANN and TMPA7 data sets better estimates the daily precipitation concentration for whole AB, but with a relative error 8%. CI estimated from satellites does not agree well with HOP over the Andes and northern Peruvian Amazon. On the other hand, the temporal variability of CI can partly be detected using CMORPH and TMPAV7 data sets over the Peruvian Andes, and central and southern Brazil. Errors in CI estimating might be related to inaccurate estimation of daily rainfall. Finally, we conclude that satellite‐based precipitation data sets are useful for analysing rainfall concentration in some regions of AB.Item Restricted Assessing the impact of downscaled winds on a regional ocean model simulation of the Humboldt system(Elsevier, 2013-05) Cambon, Gildas; Goubanova, Katerina; Marchesiello, Patrick; Dewitte, Boris; Illig, Serena; Echevin, VincentSimulating the oceanic circulation in Eastern Boundary Upwelling Systems (EBUS) is a challenging issue due to the paucity of wind stress products of a sufficiently high spatial resolution to simulate the observed upwelling dynamics. In this study, we present the results of regional simulations of the Humboldt current system (Peru and Chile coasts) to assess the value of a statistical downscaling model of surface forcing. Twin experiments that differ only from the momentum flux forcing are carried out over the 1992–2000 period that encompasses the major 1997/98 El Niño/La Niña event. It is shown that the mean biases of the oceanic circulation can be drastically reduced simply substituting the mean wind field of NCEP reanalysis by a higher resolution mean product (QuikSCAT). The statistical downscaling model improves further the simulations allowing more realistic intraseasonal and interannual coastal undercurrent variability, which is notoriously strong off Central Peru and Central Chile. Despite some limitations, our results suggest that the statistical approach may be useful to regional oceanic studies of present and future climates.Item Open Access Assessment of CMIP6 performance and projected temperature and precipitation changes over South America(Springer, 2021-06-17) Almazroui, Mansour; Ashfaq, Moetasim; Islam, M. Nazrul; Rashid, Irfan Ur; Kamil, Shahzad; Abid, Muhammad Adnan; O’Brien, Enda; Ismail, Muhammad; Reboita, Michelle Simões; Sörensson, Anna A.; Arias, Paola A.; Alves, Lincoln Muniz; Tippett, Michael K.; Saeed, Sajjad; Haarsma, Rein; Doblas‑Reyes, Francisco J.; Saeed, Fahad; Kucharski, Fred; Nadeem, Imran; Silva Vidal, Yamina; Rivera, Juan A.; Ehsan, Muhammad Azhar; Martínez Castro, Daniel; Muñoz, Ángel G.; Ali, Md. Arfan; Coppola, Erika; Sylla, Mouhamadou BambaWe evaluate the performance of a large ensemble of Global Climate Models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6) over South America for a recent past reference period and examine their projections of twenty-first century precipitation and temperature changes. The future changes are computed for two time slices (2040–2059 and 2080–2099) relative to the reference period (1995–2014) under four Shared Socioeconomic Pathways (SSPs, SSP1–2.6, SSP2–4.5, SSP3–7.0 and SSP5–8.5). The CMIP6 GCMs successfully capture the main climate characteristics across South America. However, they exhibit varying skill in the spatiotemporal distribution of precipitation and temperature at the sub-regional scale, particularly over high latitudes and altitudes. Future precipitation exhibits a decrease over the east of the northern Andes in tropical South America and the southern Andes in Chile and Amazonia, and an increase over southeastern South America and the northern Andes—a result generally consistent with earlier CMIP (3 and 5) projections. However, most of these changes remain within the range of variability of the reference period. In contrast, temperature increases are robust in terms of magnitude even under the SSP1–2.6. Future changes mostly progress monotonically from the weakest to the strongest forcing scenario, and from the mid-century to late-century projection period. There is an increase in the seasonality of the intra-annual precipitation distribution, as the wetter part of the year contributes relatively more to the annual total. Furthermore, an increasingly heavy-tailed precipitation distribution and a rightward shifted temperature distribution provide strong indications of a more intense hydrological cycle as greenhouse gas emissions increase. The relative distance of an individual GCM from the ensemble mean does not substantially vary across different scenarios. We found no clear systematic linkage between model spread about the mean in the reference period and the magnitude of simulated sub-regional climate change in the future period. Overall, these results could be useful for regional climate change impact assessments across South America.Item Restricted Assessment of different precipitation datasets and their impacts on the water balance of the Negro River basin(Elsevier, 2011-07-11) Getirana, A. C. V.; Espinoza, Jhan Carlo; Ronchail, J.; Rotunno Filho, O. C.With the objective of understanding the potential and limitations of available precipitation products for hydrological studies, this paper compares six daily and sub-daily precipitation datasets and their impacts on the water balance of the Negro River basin in the Amazon basin. The precipitation datasets contain gauge-based data [data derived from the Hybam Observatory Precipitation (HOP) dataset and provided by the Climate Prediction Center (CPC)], satellite-based data [the Global Precipitation Climatology Project (GPCP) one-degree daily and TRMM Multisatellite Precipitation Analysis (TMPA) datasets] and model-based data [the NCEP-DOE AMIP-II re-analysis (NCEP-2) and 40-year ECMWF Re-Analysis (ERA-40) datasets]. Each dataset has a common set of meteorological forcing data which are used to run the MGB-IPH hydrological model for the period from January 1998 to August 2002.Item Restricted Atmospheric black carbon observations and its valley-mountain dynamics: Eastern cordillera of the central Andes of Peru(Elsevier, 2024-08-15) Villalobos-Puma, Elver; Suárez Salas, Luis; Gillardoni, Stefania; Zubieta Barragán, Ricardo; Martínez Castro, Daniel; Miranda-Corzo, Andrea; Bonasoni, Paolo; Silva Vidal, YaminaGlacial bodies in the Peruvian Andes Mountains store and supply freshwater to hundreds of thousands of people in central Peru. Atmospheric black carbon (BC) is known to accelerate melting of snow and ice, in addition to contributing to air pollution and the health of people. Currently there is limited understanding on the sources and temporal variability of BC in valley and mountain environments in Peru. To address this problem, this study combined surface observations of BC collected during 2022–2023 with WRF model simulations and HYSPLIT trajectories to analyze the dispersion and sources of BC in valley and high elevation environments and the associated local atmospheric circulations. Results show high BC concentrations are associated with the valley-mountain wind system that occurs on both sides of the Huaytapallana mountain range. A pronounced circulation occurs on the western slopes of Huaytapallana when concentrations of BC increase during daylight hours, which transports atmospheric pollutants from cities in the Mantaro River Valley to the Huaytapallana mountain range. Low concentrations of BC are associated with circulations from the east that are channeled by the pronounced ravines of the Andes-Amazon transition. On average, during the season of highest BC concentrations (July–November), the relative contributions of fossil fuels are dominant to biomass burning at the valley observatory and are slightly lower at the Huaytapallana observatory. These results demonstrate the need to promote mitigation actions to reduce emissions of BC and air pollution associated with forest fires and local anthropogenic activity.Item Open Access Avances sobre estudios dendrocronológicos en la región costera norte del Perú para obtener un registro pasado del Fenómeno El Niño(Institut Français d'Etudes Andines, 1993) Rodríguez, Rodolfo; Woodman Pollitt, Ronald Francisco; Balsley, Ben; Mabres, Antonio; Phipps, RichardSe presenta un informe de avance sobre un proyecto dendrocronológico en búsqueda de registros de la ocurrencia del fenómeno El Niño en el pasado. El proyecto se desarrolla en la zona norte de la costa del Perú, una región muy sensible a la ocurrencia del fenómeno El Niño y de la Oscilación del Sur (ENSO). Varias especies locales han sido seleccionados para este estudio. éste incluye observaciones fenológicas del crecimiento radial y de las características del anillado de crecimiento en sus ranas y troncos. Las especies más estudiadas y con los registros de observación más largos son el Palo Santo, el Haltaco y el Sapote. Se presentan los registros de crecimiento de estas tres especies, incluyendo años secos y años El Niño. El Sapote no presenta anillos completos de crecimiento. Su crecimiento parece estar controlado principalmente por la presencia de agua en el subsuelo. Sin embargo, éste presenta variaciones, respondiendo a las estaciones y a años lluviosos. El año 1993 ha dejado huellas en su anillado muy conspicuas y sin precedentes. El Hualtaco y el Palo Santo, sí presentan anillos completos. ambos crecen en las zonas montañosas bajas, bien drenadas, que rodean las zonas planas del desierto. Su hábitat cubre varios regímenes de lluvias, de los más secos, donde ellos crecen solamente durante años. El Niño, a los más húmedos, con precipitaciones anuales estacionales, mostrando crecimiento por lo menos durante la estación de lluvias. En los dos casos, ambos muestran respuesta casi inmediata a la carencia o no de lluvias, con crecimiento radial y de nuevas hojas inmediatamente después de la ocurrencia de sólo unos cuantos centímetros de lluvia. Ante la carencia de lluvias y humedad en el suelo, rápidamente pierden sus hojas, pudiendo dormitar por años en este estado, en las zonas más secas. Un análisis preliminar de las correspondencia entre la intensidad de las precipitaciones en las zonas más lluviosas y el espesor del anillado en el Palo Santo permite ver una alta correlación entre ambas, mostrando a la vez el potencial de esta especie para establecer una cronología de la intensidad de las lluvias en el pasado, y por ende de la ocurrencia del fenómeno El Niño.Item Restricted Basin-scale analysis of rainfall and runoff in Peru (1969–2004): Pacific, Titicaca and Amazonas drainages(Taylor & Francis, 2012-04-03) Lavado Casimiro, Waldo Sven; Ronchail, Josyane; Labat, David; Espinoza, Jhan Carlo; Guyot, Jean-LoupAccording to the Peruvian agricultural ministry, the Pacific watersheds where the great cities and intense farming are located only benefit from 1% of the available freshwater in Peru. Hence a thorough knowledge of the hydrology of this region is of particular importance. In the paper, analysis of this region and of the two other main Peruvian drainages, the Titicaca and Amazonas are reported. Rainfall and runoff data collected by the Peruvian National Service of Meteorology and Hydrology (SENAMHI) and controlled under the Hydrogeodynamics of the Amazon Basin (HyBAm) project is the basis of this basin-scale study that covers the 1969–2004 period. Beyond the strong contrasting rainfall conditions that differentiate the dry coastal basins and the wet eastern lowlands, details are given about in situ runoff and per basin rainfall distribution in these regions, and about their different altitude–rainfall relationships. Rainfall and runoff variability is strong in the coastal basins at seasonal and inter-annual time scales, and related to extreme El Niño events in the Pacific Ocean. However, rainfall and runoff are more regular in the Andes and Amazonas at the inter-annual time scale. Warm sea-surface temperatures in the northern tropical Atlantic tend to produce drought in the southern Andes basins. Moreover, significant trends and change-points are observed in the runoff data of Amazonas basins where rainfall and runoff decrease, especially after the mid-1980s and during the low-stage season. Almost all the coastal basins show some change in minimum runoff during the last 35 years while no change is observed in rainfall. This means that human activity may have changed runoff in this region of Peru, but this hypothesis deserves more study.Item Restricted Boundaries of the Peruvian oxygen minimum zone shaped by coherent mesoscale dynamics(Nature Research, 2015) Bettencourt, Joao; López, Cristobal; Hernández-García, Emilio; Montes Torres, Ivonne; Sudre, Joël; Dewitte, Boris; Paulmier, Aurélien; Garçon, VéroniqueDissolved oxygen in sea water is a major factor affecting marine habitats and biogeochemical cycles. Oceanic zones with oxygen deficits represent significant portions of the area and volume of the oceans and are thought to be expanding. The Peruvian oxygen minimum zone is one of the most pronounced and lies in a region of strong mesoscale activity in the form of vortices and frontal regions, whose effect in the dynamics of the oxygen minimum zone is largely unknown. Here, we study this issue from a modeling approach and a Lagrangian point of view, using a coupled physical-biogeochemical simulation of the Peruvian oxygen minimum zone and finite-size Lyapunov exponent fields to understand the link between mesoscale dynamics and oxygen variations. Our results show that, at depths between 380 and 600 meters, mesoscale structures have a relevant dual role. First, their mean positions and paths delimit and maintain the oxygen minimum zone boundaries. Second, their high frequency fluctuations entrain oxygen across these boundaries as eddy fluxes that point towards the interior of the oxygen minimum zone and are one order of magnitude larger than mean fluxes. We conclude that these eddy fluxes contribute to the ventilation of the oxygen minimum zone.Item Restricted Calibration of speleothem δ¹⁸O records against hydroclimate instrumental records in Central Brazil(Elsevier, 2016-04) Moquet, Jean Sébastien; Cruz, F. W.; Novello, V. F.; Stríkis, N. M.; Deininger, M.; Karmann, I.; Ventura Santos, R.; Millo, C.; Apaéstegui Campos, James Emiliano; Guyot, J.-L.; Siffedine, A.; Vuille, M.; Cheng, H.; Edwards, R. L.; Santini, W.δ¹⁸O in speleothems is a powerful proxy for reconstruction of precipitation patterns in tropical and sub-tropical regions. The aim of this study is to calibrate the δ¹⁸O record of speleothems against historical precipitation and river discharge data in central Brazil, a region directly influenced by the Southern Atlantic Convergence Zone (SACZ), a major feature of the South American Monsoon System (SAMS). The present work is based on a sub-annual resolution speleothem record covering the last 141 years (the period between the years 1870 and 2011) from a cave in central Brazil. The comparison of this record with instrumental hydroclimate records since 1921 allows defining a strong relationship between precipitation variability and stable oxygen isotope ratios from speleothems. The results from a monitoring program of climatic parameters and isotopic composition of rainfall and cave seepage waters performed in the same cave, show that the rain δ¹⁸O variability is dominated by the amount effect in this region, while δ¹⁸O drip water remains almost constant over the monitored period (1.5 years). The δ¹⁸O of modern calcite, on the other hand, shows clear seasonal variations, with more negative values observed during the rainy season, which implies that other factors also influence the isotopic composition of carbonate. However, the relationship between δ¹⁸O of carbonate deposits and rainwater is supported by the results from the comparison between speleothem δ18O records and historical hydroclimate records. A significant correlation between speleothem δ¹⁸O and monsoon rainfall variability is observed on sub-decadal time scales, especially for the monsoon period (DJFM and NDJFM), once the rainfall record have been smoothed with a 7–9 years running mean. This study confirms that speleothem δ¹⁸O is directly associated with monsoon rainfall variability in central Brazil. The relationship between speleothem δ¹⁸O records and hydroclimatic historical records allows approximation of the absolute changes in mean annual rainfall during the last millennia in the SACZ/SAMS domain.