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Item Open Access Observational characterization and empirical modeling of global, direct and diffuse solar irradiances at the Peruvian central Andes(Frontiers Media, 2024-08-12) Fashé-Raymundo, Octavio; Flores-Rojas, José Luis; Estevan-Arredondo, René; Giráldez-Solano, Lucy; Suárez Salas, Luis; Sanabria-Pérez, Elias; Abi Karam, Hugo; Silva Vidal, YaminaThe present study aims to comprehensively assess the solar irradiance patterns in the western zone of the Mantaro Valley, a region of ecological and agricultural significance in the central Peruvian Andes. Leveraging radiation data from the Baseline surface Radiation Network (BSRN) sensors located in the Huancayo Geophysical Observatory (HYGO-12.04°S,75.32°W, 3350 masl) spanning from 2017 to 2022, the research delves into the seasonal variations and trends in surface solar irradiance components. Actually, the study investigates the diurnal and seasonal variations of solar irradiance components, namely diffuse (EDF), direct (EDR), and global (EG) irradiance. Results demonstrate distinct peaks and declines across seasons, with EDR and EDF exhibiting opposing seasonal trends, influencing the overall variability in, EG. Peaks of, EG occurred in spring (3.32 MJ m⁻² h⁻¹ at noon), particularly during October (24.14 MJ m⁻² day⁻¹), probably associated with biomass-burning periods and heightened aerosol optical depth (AOD). These findings highlight the impact of biomass-burning aerosols on solar radiation dynamics in the region. In general, the seasonal variability of, EG on the HYGO is lower than that observed in other regions of South America at higher latitudes and reach its maximums during spring months. Moreover, the research evaluates various irradiation models to establish correlations between sunshine hours, measured with a solid glass sphere heliograph, and, EG and EDF at different time scales, showing acceptable accuracy to predict. In addition, the sigmoid logistic function emerges as the most effective in correlating the hourly diffuse fraction and the hourly clearness index, showcasing superior performance compared to alternative functions and exhibiting strong statistical significance and providing valuable insights for future solar radiation forecasting and modeling efforts. This study offers valuable insights for solar radiation forecasting and modeling efforts, emphasizing the importance of interdisciplinary research for solar power generation, sustainable development and climate resilience in mountainous regions like the Peruvian Andes.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; Martinez-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 Emergent constraint on oxygenation of the upper South Eastern Pacific oxygen minimum zone in the twenty-first century(Nature Research, 2024-05-28) Almendra, Ivan; Dewitte, Boris; Garçon, Véronique; Muñoz, Praxedes; Parada, Carolina; Montes Torres, Ivonne; Duteil, Olaf; Paulmier, Aurélien; Pizarro, Oscar; Ramos, Marcel; Koeve, Wolfgang; Oschlies, AndreasThe erosion of marine sediments is a pressing issue for coastal areas worldwide. Established methods to mitigate coastal erosion fail to provide lasting and sustainable solutions to protect marine ecosystems. Here we demonstrate the application of mild electrical stimulations to precipitate calcareous mineral binders from seawater in the pores of marine soils via electrodeposition, an alternative approach to mitigating coastal erosion. Results of electrochemical laboratory experiments unveil that the polymorphs, precipitation sites, intrusion mechanisms, and effects of electrodeposited minerals in marine sands vary as a function of the magnitude and duration of applied voltage, soil relative density, and electrolyte ionic concentration. Surprisingly, in addition to the precipitation of calcium carbonate and magnesium hydroxide, the formation of hydromagnesite is also observed due to electrically driven fluctuations in the local pH. These electrodeposits lead to enhanced mechanical and hydraulic properties of the marine sands, indicating that electrodeposition routes could be developed to reinforce marine soils in coastal areas that more closely mimic natural systems.Item Open Access Hailstorm events in the Central Andes of Peru: insights from historical data and radar microphysics(European Geosciences Union, 2024-04-18) Valdivia, Jairo M.; Flores-Rojas, José Luis; Prado, Josep J.; Guizado, David; Villalobos-Puma, Elver; Callañaupa, Stephany; Silva Vidal, YaminaHailstorms, while fascinating from a meteorological perspective, pose significant risks to communities, agriculture, and infrastructure. In regions such as the Central Andes of Peru, the characteristics and frequency of these extreme weather events remain largely uncharted. This study fills this gap by investigating the historical frequency and vertical structure of hailstorms in this region. We analyzed historical hailstorm records dating back to 1958 alongside 4 years of observations (2017–2021) from the Parsivel2 disdrometer and a cloud-profiling radar MIRA35c. Our findings indicate a trend of decreasing hail frequency (−0.5 events per decade). However, the p value of 0.07 suggests the need for further investigation, particularly in relation to environmental changes and reporting methods. The results show that hailstorms predominantly occur during the austral summer months, with peak frequency in December, and are most common during the afternoon and early evening hours. The analysis of radar variables such as reflectivity, radial velocity, spectral width, and linear depolarization ratio (LDR) reveals distinct vertical profiles for hail events. Two case studies highlight the diversity in the radar measurements of hailstorms, underscoring the complexity of accurate hail detection. This study suggests the need for refining the Parsivel2 algorithm and further understanding its classification of hydrometeors. Additionally, the limitations of conventional radar variables for hail detection are discussed, recommending the use of LDR and Doppler spectrum analysis for future research. Our findings lay the groundwork for the development of more efficient hail detection algorithms and improved understanding of hailstorms in the Central Andes of Peru.Item Open Access Evaluación de la respuesta hidrológica a cambios de precipitación y temperatura en el altiplano peruano(Instituto Mexicano de Tecnología del Agua, 2024-01-01) Laqui, Wilber; Zubieta Barragán, Ricardo; Laqui-Vilca, Yony; Alfaro, Roberto; Laqui-Vilca, César; Aragón, LuisLas cuencas de montaña son consideradas como los sistemas hidrológicos de mayor afectación por el cambio climático, estimándose impactos significativos en los recursos hídricos y las demandas de agua. Este estudio evalúa la respuesta hidrológica de una cuenca del altiplano peruano frente a cambios de los patrones de precipitación y temperatura. El conocer con anticipación el efecto del cambio climático sobre la oferta hídrica toma relevante importancia para la toma de decisiones en la planificación a corto, mediano y largo plazos del uso del agua y la gestión de los recursos hídricos. A partir de la implementación del Modelo Integrado de Cambio Climático y Recursos Hídricos (HydroBID) se evaluaron 30 escenarios climáticos que consideraron cambios en la precipitación entre -20 y +20 %, temperatura entre 0 y 6 °C, y combinaciones de éstos formulados según las proyecciones para el área de estudio disponibles en la literatura. Los resultados mostraron que por cada 10 % de incremento de la precipitación se produjo un aumento promedio de 23.4 % en el caudal; mientras que por cada 10 % de disminución de la precipitación se generó una reducción promedio del caudal de 16 %. Asimismo, se evidenció que por cada 1 °C de subida de la temperatura se generó en promedio un 5 % de reducción del caudal. Se determinó que la variación de las tasas de precipitación, temperatura y su interacción entre ellas generarían cambios en los caudales futuros, mostrando efectos en la variación temporal y espacial de la cuenca.Item Open Access Performance of Regional Climate Model Precipitation Simulations Over the Terrain-Complex Andes-Amazon Transition Region(American Geophysical Union, 2024-01-06) Gutierrez, Ricardo A.; Junquas, Clémentine; Armijos Cardenas, Elisa Natalia; Sörensson, Anna A.; Espinoza, Jhan-CarloRegional climate models (RCMs) are widely used to assess future impacts associated with climate change at regional and local scales. RCMs must represent relevant climate variables in the present-day climate to be considered fit-for-purpose for impact assessment. This condition is particularly difficult to meet over complex regions such as the Andes-Amazon transition region, where the Andean topography and abundance of tropical rainfall regimes remain a challenge for numerical climate models. In this study, we evaluate the ability of 30 regional climate simulations (6 RCMs driven by 10 global climate models) to reproduce historical (1981–2005) rainfall climatology and temporal variability over the Andes-Amazon transition region. We assess spatio-temporal features such as spatial distribution of rainfall, focusing on the orographic effects over the Andes-Amazon “rainfall hotspots” region, and seasonal and interannual precipitation variability. The Eta RCM exhibits the highest spatial correlation (up to 0.6) and accurately reproduces mean annual precipitation and orographic precipitation patterns across the region, while some other RCMs have good performances at specific locations. Most RCMs simulate a wet bias over the highlands, particularly at the eastern Andean summits, as evidenced by the 100%–2,500% overestimations of precipitation in these regions. Annual cycles are well represented by most RCMs, but peak seasons are exaggerated, especially at equatorial locations. No RCM is particularly skillful in reproducing the interannual variability patterns. Results highlight skills and weaknesses of the different regional climate simulations, and can assist in the selection of regional climate simulations for impact studies in the Andes-Amazon transition zone.Item Open Access Seasonal Effects of Wildfires on the Physical and Chemical Properties of Soil in Andean Grassland Ecosystems in Cusco, Peru: Pending Challenges(MDPI, 2024-07-21) Roman, Melida; Zubieta Barragán, Ricardo; Ccanchi, Yerson; Martínez Grimaldo, Alejandra; Paucar, Ysai; Alvarez, Sigrid; Loayza, Julio; Ayala, FilomenoSoils are a valuable renewable resource on human timescales, and they interact with distinctive grassland ecosystems characterized by unique biodiversity and essential provision of ecosystem services, such as water supply and carbon sequestration. However, knowledge of the effects of wildfires on soil properties and nutrient availability in the Andes remains limited. Andean grasslands are currently one of the ecosystems of the Peruvian Andes most affected by wildfires. Our objective is to analyze the effect of fire activity on the physicochemical properties of soil and analyze its social context in Cusco, in the southern Andes of Peru. Soil samples were collected during five periods, spanning both the dry and rainy seasons, to characterize changes in soil properties and monitor vegetation recovery post-fire in two local communities dedicated to livestock activities. The vegetation restored after the wildfire was measured by the “step transect” method. Post-fire changes in soil properties indicate slight increases in pH, electrical conductivity, organic matter, nitrogen, phosphorus, and potassium during the onset of the rainy season; thereafter, a gradual reduction in these values was observed. This reduction can be attributed to leaching associated with the seasonal rainfall and runoff regime. Our findings indicate that one-year post-fire, the biomass in burned areas is reduced to 30–46% of the biomass in unburned areas. A complete regeneration is likely to occur in up to 4 years; this assertion is supported by the perceptions of the affected population, as expressed in interviews conducted in the two farming communities. These results are significant for decision-makers formulation of policies and regulations regarding grasslands and their seasonal restoration.Item Open Access New insights into the biennial-to-multidecadal variability of the water level fluctuation in Lake Titicaca in the 20th century(Frontiers Media, 2024-01-12) Sulca Jota, Juan Carlos; Apaéstegui Campos, James Emiliano; Tacza, JoséThe water disponibility of Lake Titicaca is important for local ecosystems, domestic water, industry, fishing, agriculture, and tourism in Peru and Bolivia. However, the water level variability in Lake Titicaca (LTWL) still needs to be understood. The fluctuations of LTWL during the 1921–2018 period are investigated using continuous wavelet techniques on high- and low-pass filters of monthly time series, ERA-20C reanalysis, sea surface temperature (SST), and water level. We also built multiple linear regression (MLR) models based on SST indices to identify the main drivers of the LTWL variability. LTWL features annual (12 months), biennial (22–28 months), interannual (80–108 months), decadal (12.75–14.06 years), interdecadal (24.83–26.50 years), and multidecadal (30–65 years) signals. The high- and low-frequency components of the LTWL are triggered by the humidity transport from the lowland toward the Lake Titicaca basin, although different forcings could cause it. The biennial band is associated with SST anomalies over the southeastern tropical Atlantic Ocean that strengthen the Bolivian High-Nordeste Low system. The interannual band is associated with the southern South Atlantic SST anomalies, which modulate the position of the Bolivian High. According to the MLR models, the decadal and interdecadal components of the LTWL can be explained by the linear combination of the decadal and interdecadal variability of the Pacific and Atlantic SST anomalies (r > 0.83, p < 0.05). In contrast, the multidecadal component of the LTWL is driven by the multidecadal component of the North Atlantic SST anomalies (AMO) and the southern South Atlantic SST anomalies. Moreover, the monthly time series of LTWL exhibits four breakpoints. The signs of the first four trends follow the change of phases of the multidecadal component of LTWL, while the fifth trend is zero attributable to the diminished amplitude of the interdecadal component of LTWL.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 Open Access Explained predictions of strong eastern Pacific El Niño events using deep learning(Nature Research, 2023-11-30) Rivera Tello, Gerardo A.; Takahashi, Ken; Karamperidou, ChristinaGlobal and regional impacts of El Niño-Southern Oscillation (ENSO) are sensitive to the details of the pattern of anomalous ocean warming and cooling, such as the contrasts between the eastern and central Pacific. However, skillful prediction of such ENSO diversity remains a challenge even a few months in advance. Here, we present an experimental forecast with a deep learning model (IGP-UHM AI model v1.0) for the E (eastern Pacific) and C (central Pacific) ENSO diversity indices, specialized on the onset of strong eastern Pacific El Niño events by including a classification output. We find that higher ENSO nonlinearity is associated with better skill, with potential implications for ENSO predictability in a warming climate. When initialized in May 2023, our model predicts the persistence of El Niño conditions in the eastern Pacific into 2024, but with decreasing strength, similar to 2015–2016 but much weaker than 1997–1998. In contrast to the more typical El Niño development in 1997 and 2015, in addition to the ongoing eastern Pacific warming, an eXplainable Artificial Intelligence analysis for 2023 identifies weak warm surface, increased sea level and westerly wind anomalies in the western Pacific as precursors, countered by warm surface and southerly wind anomalies in the northern Atlantic.Item Restricted Temporal dynamics of glacier retreat and its relationship with local climate in Cordillera Apolobamba, Peru(Springer, 2024-04) Laqui, Wilber; Zubieta Barragán, Ricardo; Laqui-Vilca, Yony; Calizaya, Elmer; Laqui-Vilca, CésarGlaciers play a pivotal role as essential water sources, and monitoring their dynamics is crucial for understanding the profound impacts of climate change. This study presents a comprehensive assessment of the temporal dynamics of glacier retreat and its relationship with the local climate in Cordillera Apolobamba, Peru, spanning 1986 to 2015. Using Landsat satellite imagery and the Normalized Difference Snow Index (NDSI), we quantify changes in glacial cover at five-year intervals, starting in 1986. Additionally, we explore the climate drivers associated with these changes by analyzing local climatic data. The results reveal a remarkable and concerning trend in the temporal evolution of glacial areas in the CA. By 2015, the extent of glacial retreat had reached approximately 51.84% of the surface area estimated in 1986, with an average annual loss rate of 0.79 km²/year. This retreat corresponds to a substantial reduction in glacial volume over the study period. This study unveils direct and inverse relationships between precipitation, temperature, and the glacier retreat rate. This discerns that temperature predominantly drives the loss of glacier area, while the glacier retreat rate is conditioned by precipitation. The results provide crucial data for policymakers, stakeholders, and researchers striving to understand the intricate interplay between climate variables and glacial dynamics and their broader implications for water resource management in high-altitude regions.Item Open Access Reflections on the impact and response to the Peruvian 2017 Coastal El Niño event: Looking to the past to prepare for the future(Public Library of Science, 2023-09-26) Yglesias-González, Marisol; Valdés-Velásquez, Armando; Hartinger, Stella M.; Takahashi, Ken; Salvatierra, Guillermo; Velarde, Rodrigo; Contreras, Alvaro; Santa María, Hugo; Romanello, Marina; Paz-Soldán, Valerie; Bazo, Juan; Lescano, Andrés G.Climate-related phenomena in Peru have been slowly but continuously changing in recent years beyond historical variability. These include sea surface temperature increases, irregular precipitation patterns and reduction of glacier-covered areas. In addition, climate scenarios show amplification in rainfall variability related to the warmer conditions associated with El Niño events. Extreme weather can affect human health, increase shocks and stresses to the health systems, and cause large economic losses. In this article, we study the characteristics of El Niño events in Peru, its health and economic impacts and we discuss government preparedness for this kind of event, identify gaps in response, and provide evidence to inform adequate planning for future events and mitigating impacts on highly vulnerable regions and populations. This is the first case study to review the impact of a Coastal El Niño event on Peru’s economy, public health, and governance. The 2017 event was the third strongest El Niño event according to literature, in terms of precipitation and river flooding and caused important economic losses and health impacts. At a national level, these findings expose a need for careful consideration of the potential limitations of policies linked to disaster prevention and preparedness when dealing with El Niño events. El Niño-related policies should be based on local-level risk analysis and efficient preparedness measures in the face of emergencies.Item Restricted Spatial and Temporal Distribution of Black Carbon in Peru from the Analysis of Biomass Burning Sources and the Use of Numerical Models(Springer, 2023-06) Moya-Álvarez, Aldo S.; Estevan, René; Martínez-Castro, Daniel; Silva Vidal, YaminaThe spatial and temporal distribution of biomass burning in Peru and neighboring countries was analyzed during the 2018–2020 period, with emphasis on 2019. To determine the glaciers most affected by BC as a consequence of vegetation burning, simulations were carried out with the WRF-CHEM model, and to diagnose the origin of BC particles received by the Huaytapallana glacier, backward trajectories were built with the HYSPLIT model. It was found that, during the studied period, the burning of biomass emitted large amounts of BC into the atmosphere, while the number of fires in Peru began its most notable increase in the month of July, with maxima between August and September. Comparisons of the number of outbreaks with the Aerosol Optical Depth (AOD) measured at the Huancayo observatory showed a significant correlation. The Ucayali region is the one that contributes the greatest number of outbreaks and the greatest emissions are produced in the south of Loreto. The WRF model showed that the concentrations in July are still low in relation to the August–October period. The mountain ranges that received the greatest impact from BC emissions were Huaytapallana, Huagoruncho, and Vilcabamba. BC transport is mainly oriented from north to south, moving the particles from the areas of greatest burning to the glaciers located in the center and south of the country. BC concentrations over the Cordillera Blanca were lower. The diagnosis of the backward trajectories corroborated the results of WRF-CHEM and showed trajectories mostly from the north.Item Open Access Comparison between the Operational and Statistical Daily Maximum and Minimum Temperature Forecasts on the Central Coast of Peru(AMS, 2023-04-06) Aliaga-Nestares, Vannia; De La Cruz, Gustavo; Takahashi, KenMultiple linear regression models were developed for 1–3-day lead forecasts of maximum and minimum temperature for two locations in the city of Lima, on the central coast of Peru (12°S), and contrasted with the operational forecasts issued by the National Meteorological and Hydrological Service—SENAMHI and the output of a regional numerical atmospheric model. We developed empirical models, fitted to data from the 2000–13 period, and verified their skill for the 2014–19 period. Since El Niño produces a strong low-frequency signal, the models focus on the high-frequency weather and subseasonal variability (60-day cutoff). The empirical models outperformed the operational forecasts and the numerical model. For instance, the high-frequency annual correlation coefficient and root-mean-square error (RMSE) for the 1-day lead forecasts were 0.37°–0.53° and 0.74°–1.76°C for the empirical model, respectively, but from around −0.05° to 0.24° and 0.88°–4.21°C in the operational case. Only three predictors were considered for the models, including persistence and large-scale atmospheric indices. Contrary to our belief, the model skill was lowest for the austral winter (June–August), when the extratropical influence is largest, suggesting an enhanced role of local effects. Including local specific humidity as a predictor for minimum temperature at the inland location substantially increased the skill and reduced its seasonality. There were cases in which both the operational and empirical forecast had similar strong errors and we suggest mesoscale circulations, such as the low-level cyclonic vortex over the ocean, as the culprit. Incorporating such information could be valuable for improving the forecasts.Item Restricted Performance of heat spots obtained from satellite datasets to represent burned areas in Andean ecosystems of Cusco, Peru(Elsevier, 2023-07-08) Zubieta Barragán, Ricardo; Ccanchi, Yerson; Liza, RominaThe combustion of biomass is a prevalent practice in the Andes. Often, these burns escape control and escalate into wildfires. However, the investigation of unreported fire incidents has not received the same level of attention as reported wildfires. Satellite provide an alternative information source for studying wildfires. Given the scarcity of wildfire response tools, it is imperative to develop strategies to prevent burns in regions where human activity typically triggers wildfires. This study aims to assess the efficacy of heat spot data obtained from satellite datasets in identifying fire activity in the Peruvian Andes. The study utilized MODIS (MCD14DL product) and VIIRS (SUOMI and JPSS-1 products) satellite datasets to characterize fire activity through heat spot detection. Additionally, the study employed the normalized burned area index (NBR), a valuable indicator for mapping burned areas. Our findings indicate that MODIS and VIIRS heat spots demonstrate a high level of reliability in detecting active fires (commission errors of ∼1%). However, the detection of burned areas not captured by MODIS or VIIRS heat spots was significantly high (omission errors of ∼90%). Nevertheless, this detection deficiency decreased for larger burn areas (errors of omission between 10 and 30% for burned areas between 50 and 100 ha, using JPSS-1 VIIRS). These results suggest that satellite heat spots are inadequate for identifying burn practices, which encompass small-scale and short-duration fire activities (lasting only hours). The outcomes of this study enhance our understanding of the suitability of heat spot detection for wildfire prevention in the Peruvian Andes.Item Open Access On the interpretation of changes in the subtropical oxygen minimum zone volume off Chile during two La Niña events (2001 and 2007)(Frontiers Media, 2023-07-04) Pizarro-Koch, Matías; Pizarro, Oscar; Dewitte, Boris; Montes Torres, Ivonne; Paulmier, Aurélien; Garçon, Véronique; Sepulveda, Hector Hito; Corredor-Acosta, Andrea; Aguirre, Catalina; Ramos, MarcelOxygen minimum zones (OMZs) are extended oceanic regions for which dissolved oxygen concentration is extremely low. They are suspected to be expanding in response to global warming. However, currently, the mechanisms by which OMZ varies in response to climate variability are still uncertain. Here, the variability of the subtropical OMZ off central Chile of a regional coupled physical–biogeochemical regional model simulation was analyzed for the period 2000–2008, noting that its fluctuations were significant despite the relatively weak amplitude of the El Niño/Southern Oscillation (ENSO). In particular, the interannual variability in the OMZ volume (OMZVOL, defined as the volume with dissolved oxygen concentration (DO) ≤ 45μM) was approximately 38% larger than that of the seasonal cycle, with maximum and minimum anomalies of OMZVOL taking place during two cold La Niña (LN) years (2001 and 2007). The model analyses further reveal that these anomalies resulted from a combined effect of changes in (1) the oxygen-poor waters poleward transport by the Peru–Chile undercurrent (PCUC), (2) the intensity of quasi-zonal jets influencing the transport of water to and from the OMZ, and (3) the zonal DO transport related to mesoscale eddy activity. Specifically, the interannual variability of the PCUC modulated primarily the DO contents of the OMZ core [(DO) ≤ 20μM] and secondarily the OMZVOL, while cross-shore DO transport by the zonal jets and the eddy fluxes played a major role in ventilating and shaping the offshore extent of the OMZ. When the OMZVOL was maximum (minimum), the PCUC transport was slightly increased (reduced), which was associated with a reduction (increase) in the ventilation of the OMZ through negative (positive) anomalies of zonal advection and DO eddy fluxes. Our results demonstrate that significant natural interannual variability in the subtropical OMZ off Chile originates from the interplay between oceanic equatorial teleconnection (PCUC transport) and local non-linear dynamics (the zonal jets and mesoscale eddies).Item Restricted Recent Deoxygenation of Patagonian Fjord Subsurface Waters Connected to the Peru–Chile Undercurrent and Equatorial Subsurface Water Variability(American Geophysical Union, 2023-05-26) Linford, P.; Pérez-Santos, I.; Montes Torres, Ivonne; Dewitte, B.; Buchan, S.; Narváez, D.; Saldías, G.; Pinilla, E.; Garreaud, R.; Díaz, P.; Schwerter, C.; Montero, P.; Rodríguez-Villegas, C.; Cáceres-Soto, M.; Mancilla-Gutiérrez, G.; Altamirano, R.In recent decades, global dissolved oxygen (DO) measurements have registered a decrease of ∼1%–2% in oxygen content, raising concerns regarding the negative impacts of ocean deoxygenation on marine life and the greenhouse gas cycle. By combining in situ data from 2016 to 2022, satellite remote sensing, and outputs from a physical-biogeochemical model, we revealed the deoxygenation process in the Patagonian fjords for the first time. Deoxygenation was associated with the advection of equatorial subsurface water (ESSW) mass into the northern region of Patagonia. An analysis of the circulation regime using the Mercator-Ocean global high-resolution model confirmed the importance of the Peru–Chile undercurrent (PCUC) in transporting the ESSW poleward, contributing to the entrance of ESSW into the northern Patagonian fjords. A mooring system installed in the water interchange area between the Pacific Ocean and Patagonian fjords detected a decreasing DO of −21.66 μmol L⁻¹ over 7 years, which was explained by the increase in PCUC transport of 1.46 Sv. Inside the Puyuhuapi fjord system, a second DO time series exhibited more marked deoxygenation with −88.6 μmol L⁻¹ over 3 years linked with the influence of ESSW and local processes, such as DO consumption by the organic matter degradation. The recent deoxygenation registered in the northern Patagonian fjords demonstrates the significance of studying DO in the context of reducing the global oxygen content, further warranting the quantification of the impacts of deoxygenation on life cycles of marine organisms that inhabit the Patagonian fjords and channels and the Humboldt current system.Item Open Access Flooding risk of cropland areas by repiquetes in the western Amazon basin: A case study of Peruvian Tamshiyacu City(Elsevier, 2023-06) Valenzuela, Jonathan; Figueroa, Manuel; Armijos Cardenas, Elisa Natalia; Espinoza, Jhan-Carlo; Wongchuig, Sly; Ramirez-Avila, John J.Study región: The western Amazon basin at Tamshiyacu gauging station (near the Iquitos City) hosts floodplain agriculture that can be affected by the sudden reversal in direction of water levels known as “repiquetes” that produce intermittent flooding. Study focus: This study assesses repiquete flooding risk in riparian crop areas based on statistical analyses of repiquete events registered from 1996 to 2018, hydraulic modeling to estimate flooded extension, and assessment of climatological characteristics during the formation of repiquetes. New hydrological insights: Floods (≥ 20 cm) produced by repiquetes in riparian crop areas between 83.00 and 88.00 m above sea level (masl) occur 1.8 times per year. However, not all elevation ranges have the same flooding risk to crops. Terrain elevations between 85.31 and 87.00 masl have a reduced flooding risk of 0.35 per year. Likewise, areas with elevations between 87.00 and 88.00 masl (43% of the total area) were not affected by repiquetes. Extreme repiquetes (study cases of 2002 and 2008) have been influenced by the increase of atmospheric moisture flux convergence and precipitation over both the northern Ucayali and Marañón basins through the six previous days. Flood impacts from the extreme event of 2002 (2008) could have reached 40% (25%) of the available area for agriculture at the initiation of the repiquete.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 Open Access Evaluating future climate change exposure of marine habitat in the South East Pacific based on metabolic constraints(Frontiers Media, 2023-01-05) Parouffe, Alexandra; Garçon, Véronique; Dewitte, Boris; Paulmier, Aurélien; Montes Torres, Ivonne; Parada, Carolina; Mecho, Ariadna; Veliz, DavidOn-going climate change is now recognized to yield physiological stresses on marine species, with potentially detrimental effects on ecosystems. Here, we evaluate the prospect of using climate velocities (CV) of the metabolic index (Φ) for assessing changes in habitat in the South East Pacific. Our approach is based on a species with mean ecophysiotype (i.e. model species) and the use of a global Earth System Model simulation (CESM-LE) under RCP 8.5 scenario. The SEP is chosen as a case study as it hosts an Oxygen Minimum Zone and seamounts systems sustaining local communities through artisanal fisheries. Our results indicate that CVΦ pattern is mainly constrained by the oxygen distribution and that its sign is affected by contrasting oxygen trends (including a re-oxygenation in the upper OMZ) and warming. We further show that CVΦ is weakly dependent on physiological traits composing Φ, which conveys to this metrics some value for inferring the projected mean displacement and potential changes in viability of metabolic habitat in a region where physiological data are scarce. Based on sensitivity experiments to physiological traits and natural variability, we propose a general method for inferring broad areas of climate change exposure regardless of species-specific Φ. We show in particular that for the model used here, the upper OMZ region can be considered a “safe” area for the species with ecophysiotype close to that of 71 species used to derive the model species. Limitations of the approach and perspectives of this work are also discussed.