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Item Open Access Estimación de lluvias extremas mediante un enfoque de análisis regional y datos satelitales en Cusco, Perú(Instituto Mexicano de Tecnología del Agua, 2024-09-01) Aragón, Luis; Lavado-Casimiro, Waldo; Montesinos, Cristian; Zubieta Barragán, Ricardo; Laqui, WilberLa frecuencia y magnitud de los eventos climáticos extremos de precipitación han aumentado de forma significativa en varios países del mundo, incluido Perú. Estos hechos causan pérdidas económicas y humanas, especialmente en países en vías de desarrollo. La información y metodologías que permitan prevenir o diseñar estrategias para afrontarlas son escasas o inexistentes. El objetivo de esta investigación fue analizar la capacidad del producto satelital IMERG (Integrated MultisatellitE Retrievals) del satélite GPM (Global Precipitation Measurement) y datos observados a partir de estaciones meteorológicas mediante un enfoque mixto para estimar la distribución de lluvias extremas en la región del Cusco, ubicado al sur del Perú. Este enfoque mixto aprovechó las ventajas que ofrecen ambas fuentes de información, como es la solidez de los datos observados a lo largo de varios años y la resolución temporal horaria del producto satelital. La metodología se basó en una curva de crecimiento de cada región homogénea, factor de corrección y parámetros que estiman la función intensidad y duración para toda la región Cusco. Los resultados se evaluaron mediante validación cruzada entre los valores de precipitación diaria obtenidos del producto IMERG, enfoque mixto y precipitación observada para periodos de retorno de 2, 5, 10, 20, 50, 100, 200, 500 y 1 000 años. Los resultados sugieren que la combinación de datos observados de lluvia y del satélite IMERG puede ser una alternativa para estimar lluvias extremas en la región Cusco.Item Open Access Atmospheric aerosols and air quality in the 2022 dry season in Huancayo-Perú(Universidade Federal do Rio de Janeiro, 2024-05-15) Angeles Vasquez, Roberto; Angeles Suazo, Julio Miguel; Abi Karam, Hugo; Flores Rojas, José Luis; Suarez Salas, Luis; Lavado-Meza, Carmencita; Angeles Suazo, Nataly; Boza Ccora, Fernando; De la Cruz-Cerron, Leonel; Zarate Quiñones, RosaThis work presents results of Aerosol Optical Depth (AOD) and Direct Radiative Force (DRF) at the top of the atmosphere (TOA), obtained during monitoring campaigns carried out at the Huancayo Observatory of the Geophysical Institute of Peru (OH-IGP ) in April and August 2022. In these campaigns, a Sun CIMEL photometer was used to measure the microphysical and optical properties of aerosols at wavelengths ranging from 340 to 1020 nm, and a low-cost Purple-air sensor to quantify the concentration of material particulate (PM), in fine and coarse modes. The AOD results indicated values in the range 0.06-0.22. The daily averages of PM2.5 and PM10 did not exceed Peru’s current Environmental Quality Standards (50 μg/m³ and 100 μg/m³). The air quality index (AQI) calculated for PM2.5 and PM10 was classified as good. On some days during the campaigns, the air quality was classified as moderate. These results contribute to a better understanding of the current climatic conditions of the Peruvian Altiplano.Item Open Access Latitudinal and temporal distribution of aerosols and precipitable water vapor in the tropical Andes from AERONET, sounding, and MERRA‑2 data(Nature Research, 2024-01-09) Cazorla, María; Giles, David M.; Herrera, Edgar; Suárez Salas, Luis; Estevan, Rene; Andrade, Marcos; Bastidas, ÁlvaroThe aerosol and precipitable water vapor (PW) distribution over the tropical Andes region is characterized using Aerosol Robotic Network (AERONET) observations at stations in Medellin (Colombia), Quito (Ecuador), Huancayo (Peru), and La Paz (Bolivia). AERONET aerosol optical depth (AOD) is interpreted using PM₂.₅ data when available. Columnar water vapor derived from ozone soundings at Quito is used to compare against AERONET PW. MERRA-2 data are used to complement analyses. Urban pollution and biomass burning smoke (BBS) dominate the regional aerosol composition. AOD and PM₂.₅ yearly cycles for coincident measurements correlate linearly at Medellin and Quito. The Andes cordillera’s orientation and elevation funnel or block BBS transport into valleys or highlands during the two fire seasons that systematically impact South America. The February–March season north of Colombia and the Colombian-Venezuelan border directly impacts Medellin. Possibly, the March aerosol signal over Quito has a long-range transport component. At Huancayo and La Paz, AOD increases in September due to the influence of BBS in the Amazon. AERONET PW and sounding data correlate linearly but a dry bias with respect to soundings was identified in AERONET. PW and rainfall progressively decrease from north to south due to increasing altitude. This regional diagnosis is an underlying basis to evaluate future changes in aerosol and PW given prevailing conditions of rapidly changing atmospheric composition.Item Open Access Hydrometeors Distribution in Intense Precipitating Cloud Cells Over the Earth’s During Two Rainfall Seasons(Springer, 2024-01-25) Kumar, Shailendra; Flores Rojas, José Luis; Moya Álvarez, Aldo Saturnino; Martínez Castro, Daniel; Silva Vidal, YaminaIn the present study, we used attenuated corrected radar refectivity factor (Zₑ) and rain-drop size distribution (DSD) to investigate the hydrometeors distribution in the intense precipitating cloud cells (PCCs) from precipitation radar (PR) onboard on Global Precipitation Measurement (GPM). The DSD parameters consist of two variables, namely, mass-weighted mean diameter (Dₘ) in mm and normalized scaling parameters for hydrometeors concentration (Nw) in mm⁻¹ m⁻³. We defned two types of PCCs, which are the proxies for the intense rainfall events. First PCC is termed as Cumulonimbus Towers (CbTs), which consist of Zₑ> =20 dBZ at 12 km altitude, and its base height must be less than 3 km altitude. We also defned intense convective clouds (ICCs), which consist of Zₑ>30 (40) dBZ at 8 km (3 km), respectively, and are termed as ICC8 and ICC3, respectively. The spatial distribution reveals that continental areas consist of a higher frequency of CbTs and ICC8s compared to oceanic areas, whereas ICC3s are uniformly distributed over tropical land and oceanic areas. The DSD parameters reveal that intense PCCs have larger hydrometeors (Dₘ), whereas weaker (less Zₑ) vertical profles consist of higher concentration (Nw) of smaller hydrometeors (Dₘ). Land consists of larger hydrometeors (Dₘ) compared to oceanic areas, and diferences are higher in liquid phase regimes compared to mixed phase regimes. The vertical profles of Zₑ, Dₘ and Nw are showing the higher regional diferences among the diferent land-based areas, compared to various tropical ocean basins. Western Himalaya Foothills and Sierra De Cordoba consist of the strongest vertical profles with the largest Dₘ on the Earth’s áreas during JJAS and DJFM months, respectively.Item Open Access Future changes of precipitation types in the Peruvian Andes(Nature Research, 2024-09-30) Llactayo, Valeria; Valdivia Prado, Jairo Michael; Yarleque, Christian; Callañaupa, Stephany; Villalobos‑Puma, Elver; Guizado, David; Alvarado‑Lugo, RobertIn high-altitude regions, such as the Peruvian Andes, understanding the transformation of precipitation types under climate change is critical to the sustainability of water resources and the survival of glaciers. In this study, we investigate the distribution and types of precipitation on a tropical glacier in the Peruvian Central Andes. We utilized data from an optical-laser disdrometer and compact weather station installed at 4709 m ASL, combined with future climate scenarios from the CMIP6 project, to model potential future changes in precipitation types. Our findings highlight that increasing temperatures could lead to significant reductions in solid-phase precipitation, including snow, graupel and hail, with implications for the mass balance of Andean glaciers. For instance, a 2 °C rise might result in less than 10% of precipitation as solid, in regard to the present day, transforming the hydrological processes of the region. The two future climate scenarios from the CMIP6 project, SSP2-4.5 and SSP5-8.5, offer a broad perspective on potential climate outcomes that could impact precipitation patterns in the Andes. Our study underscores the need to revisit and expand our understanding of high-altitude precipitation in the face of climate change, paving the way for improved water resource management strategies and sustainable glacier preservation efforts in these fragile ecosystems.Item Open Access Chemical composition and trajectories of atmospheric particles at the Machu Picchu Peruvian Antarctic scientific station (62.09° S, 58.47° W)(Universidad Autónoma de México, 2024-04-25) Álvarez-Tolentino, Daniel; Suárez Salas, Luis; Pomalaya-Valdez, José; Barja, BorisAntarctica is a remote and relatively pristine region, but the regional transport of aerosols may be a source of pollution, especially in the Antarctic Peninsula. Few studies have characterized atmospheric aerosols and evaluated the contribution of their emission sources. The Peruvian Antarctic research station Machu Pichu (ECAMP, by its Spanish acronym) is located on King George Island in the Antarctic Peninsula. During February 2020, atmospheric particulate mass (PM ₁₀ and PM ₂.₅) was sampled and analyzed to characterize its elemental composition and was supplemented by measurements of equivalent black carbon and aerosol size distributions. Chemical elements were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), multivariate techniques, and enrichment factors. The most abundant elements in PM ₁₀ and PM ₂.₅ were Na, Fe, Mg, and Si, with the most important local sources being marine (Na, Mg, Mn, Ca) and crustal (Fe, Al, P). Sources of weathering (Ba and Si) from glacial thawing and sources of combustion linked to the use of oil (V) and emission of black carbon were recorded. Air mass back-trajectory analysis using the HYSPLIT model helped identify external sources of particulate matter in the air masses reaching the ECAMP site. Overall, this study supports the growing evidence of the anthropogenic impact of distant and local sources on the white continent.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 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 Urban heat island and increase in temperature on urban roads in Huancayo/Peru [Isla de calor urbano e incremento de temperatura en vías urbanas en Huancayo/Perú](LACCEI, Latin American and Caribbean Consortium of Engineering Institutions, 2024-07) Angeles Vasquez, Roberto; Angeles Suazo, Julio; Flores Rojas, José Luis; Boza Ccora, Fernando; Angeles Suazo, Nataly; Suarez Salas, Luis; Abi Karam, HugoLa rápida urbanización de las ciudades está cambiando el clima local, lo que genera altas temperaturas y entornos urbanos densos y difíciles, carentes de agua y vegetación[1]. La presente contribución estima la intensidad de Isla de Calor Urbano Superficial (ICUS) durante el periodo 2001 – 2022 para el Área Metropolitana de Huancayo (AMH), Perú. Se cuantificó formación de la Isla de Calor Urbano Superficial, a partir de 2 métodos: el primero es el método de Streutker, el cual ajusta la temperatura superficial del suelo (LST) (superficie urbana y rural) a una superficie Gaussiana. El segundo, método de cuantil propuesto por José Flores, usa la diferencia entre el cuantil 0.95 de LST del área urbana y la mediana del LST del área rural. Ambos métodos usan data de sensoramiento remoto de LST a 0.05⁰ de resolución, obtenido del sensor MODIS a bordo del satélite TERRA y AQUA. Para el AMH, durante los periodos diurnos, la intensidad de ICUS en marzo y julio representan el máximo y mínimo incremento. El periodo nocturno, presentó valores máximo y mínimo en agosto y diciembre respectivamente. En general se consiguió mostrar las principales causas del incremento de temperatura superficial es el pavimento asfaltado, donde la temperatura puede ser hasta 60 °C. Por ello es importante proponer medidas de mitigación como construcciones y pavimentos sostenible que ayuden a mitigar el incremento de temperatura superficial. Así como la importancia de considerar la Floresta o plantaciones vegetales en un diseño o zonificación urbana.Item Open Access GC Insights: Lessons from participatory water quality research in the upper Santa River basin, Peru(Copernicus Publications, 2024-06-27) Rangecroft, Sally; Clason, Caroline; Dextre, Rosa Maria; Richter, Isabel; Kelly, Claire; Turin, Cecilia; Grados-Bueno, Claudia V.; Fuentealba, Beatriz; Camacho Hernandez, Mirtha; Morera Julca, Sergio Byron; Martin, John; Guy, John AdamHere we share four key lessons from an interdisciplinary project (Nuestro Rio) that gathered community perspectives on local water quality in the Santa River basin (Peru) utilising a digital technological approach where we collected data via a novel photo elicitation app, supported by a field work campaign. The lessons explored in this article provide insights into challenges and opportunities for researchers considering developing technological tools for encouraging participation and engagement in marginalised communities.Item Open Access Dynamic atmospheric mechanisms associated with the diurnal cycle of hydrometeors and precipitation in the Andes–Amazon transition zone of central Peru during the summer season(Springer, 2024-04-04) Villalobos-Puma, Elver; Morales, Annareli; Martinez-Castro, Daniel; Valdivia Prado, Jairo Michael; Lavado-Casimiro, Waldo; Santiago, AlexzanderThe diurnal cycle of total hydrometeor availability and its associated patterns of atmospheric circulation is studied over a connected Andes–Amazon (A–A) system in the central region of Peru during the summer season. Surface precipitation depends on the amount of hydrometeors that occur in the atmosphere and its atmospheric dynamics. Hydrometeors and the precipitation efficiency index were estimated using radar of the core satellite of the GPM system (N-GPM) for the period 2014–2022. The atmospheric dynamics were analyzed using the regional Weather Research and Forecasting (WRF) model. According to the results, the Andes mountain range produces precipitation at a surface level more efficiently during the afternoon and early evening hours (12–19 LT) due to the convergence of the thermal mesoscale circulations transporting moisture fluxes from the east and west. Both generate convective multicells along the Andes mountain range. The circulation from the west intensifies during the day, causing the displacement of the chain of convective multicells towards the east and producing hydrometeors and intense precipitations in the inter-Andean valleys. The A–A transition zone is more efficient in producing precipitation during the early hours of the day (00–07 LT) due to an increase in the northern circulation associated with the low-level jets and a change in the magnitude of the horizontal winds. Northerly winds enter the A–A transition zone with increased intensity and leave with reduced intensity. This mechanism is driven by the effect of the topographical barrier and the masses of cold air located in high areas on the eastern flank of the Andes. These factors generate significant updrafts and, therefore, the formation of storm clouds with high concentrations of hydrometeors and precipitation on the surface.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; 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 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 Prado, Jairo Michael; 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.