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  • ItemOpen 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, José
    The 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.
  • ItemRestricted
    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 Emiliano
    The 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.
  • ItemOpen 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, Christina
    Global 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.
  • ItemRestricted
    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, César
    Glaciers 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.
  • ItemOpen 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.
  • ItemRestricted
    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, Yamina
    The 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.
  • ItemOpen 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, Ken
    Multiple 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.
  • ItemRestricted
    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, Romina
    The 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.
  • ItemOpen 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, Marcel
    Oxygen 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).
  • ItemRestricted
    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.
  • ItemOpen 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.
  • ItemOpen 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, Angela
    The Mantaro River Basin is one of the most important regions in the central Peruvian Andes in terms of hydropower generation and agricultural production. Contributions to better understanding of the climate and hydrological dynamics are vital for this region and constitute key information to support regional water security and socioeconomic resilience. This study presents eight years of monthly isotopic precipitation information (δ¹⁸O, Dxs) collected in the Mantaro River Basin. The isotopic signals were evaluated in terms of moisture sources, including local and regional climatic parameters, to interpret their variability at monthly and interannual timescales. It is proposed that the degree of rainout upstream and the transport history of air masses, also related to regional atmospheric features, are the main factors influencing the δ¹⁸O variability. Moreover, significant 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.
  • ItemOpen 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, David
    On-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.
  • ItemOpen Access
    Climate Change Impacts on Eastern Boundary Upwelling Systems
    (Annual Reviews, 2023-01) Bograd, Steven J.; Jacox, Michael G.; Hazen, Elliott L.; Lovecchio, Elisa; Montes Torres, Ivonne; Pozo Buil, Mercedes; Shannon, Lynne J.; Sydeman, William J.; Rykaczewski, Ryan R.
    The world's eastern boundary upwelling systems (EBUSs) contribute disproportionately to global ocean productivity and provide critical ecosystem services to human society. The impact of climate change on EBUSs and the ecosystems they support is thus a subject of considerable interest. Here, we review hypotheses of climate-driven change in the physics, biogeochemistry, and ecology of EBUSs; describe observed changes over recent decades; and present projected changes over the twenty-first century. Similarities in historical and projected change among EBUSs include a trend toward upwelling intensification in poleward regions, mitigatedwarming in near-coastal regions where upwelling intensifies, and enhanced water-column stratification and a shoaling mixed layer. However, there remains significant uncertainty in how EBUSs will evolve with climate change, particularly in how the sometimes competing changes in upwelling intensity, source-water chemistry, and stratification will affect productivity and ecosystem structure. We summarize the commonalities and differences in historical and projected change in EBUSs and conclude with an assessment of key remaining uncertainties and questions. Future studies will need to address these questions to better understand, project, and adapt to climate-driven changes in EBUSs.
  • ItemRestricted
    The role of drought conditions on the recent increase in wildfire occurrence in the high Andean regions of Peru
    (CSIRO Publishing, 2023-01-24) Zubieta Barragán, Ricardo; Ccanchi, Yerson; Martínez Grimaldo, Alejandra; Saavedra Huanca, Miguel; Norabuena Ortiz, Edmundo; Alvarez, Sigrid; Ilbay, Mercy
    Wildfire occurrence has increased sharply in the last two decades in the Peruvian Andes. There is, however, little research on wildfires and their impacts. This study explores the conditions conducive to wildfire during 2020. MODIS images were collected to estimate the development of vegetation. In addition, ground-based monthly and satellite-based daily precipitation data were collected. Daily precipitation regularity was evaluated using a concentration index (CI), while monthly precipitation was used to estimate the Standard Precipitation Index (SPI). We used also the Global Vegetation Moisture Index (GVMI), which is a useful indicator of vegetation dynamics based on vegetation moisture. Our results do not indicate a direct link between rainfall regularity (lowest CI values) and development of vegetation. Although the SPI drought analysis using seasonal rainfall indicated nearly normal conditions during 2019–2020, analysis of dry-day frequency (DDF) suggests that the dry period played an important role between September and November 2020, producing conditions similar to the droughts of 2005, 2010 and 2016. GVMI also showed below-average values from April to November. We corroborate the usefulness of DDF for monitoring the potential increase in wildfire conditions. A controlled burn policy could offer a more useful way to reduce the impacts of wildfire.
  • ItemRestricted
    Potential conditions for fire occurrence in vegetation in the Peruvian Andes
    (CSIRO Publishing, 2021-10-12) Zubieta Barragán, Ricardo; Prudencio, Fernando; Ccanchi, Yerson; Saavedra Huanca, Miguel; Sulca Jota, Juan Carlos; Reupo, Jorge; Alarco, Glory
    Fire activity in the Peruvian Andes has increased significantly in recent decades, but climatic parameters associated with drought, which may indirectly contribute to the occurrence of severe forest fires, have not yet been investigated. Because fire prevention tools are scarce, strategies for deterring burning are necessary in order to reduce impacts in regions where forest fires usually result from human activity. This study explores the conditions conducive to forest fire in the Andes of Peru. Daily precipitation and temperature observed data from the PISCO gridded dataset for the 2002–2016 period were used. In addition, MODIS satellite images (MOD09A1 product) were collected to characterise Andean vegetation using spectral indices. Analysis of daily temperature and rainfall indicates that climatic parameters such as cumulative precipitation, dry-day frequency and hot-day frequency are statistically associated with conditions that could contribute to increased forest fire occurrence. Our findings suggest that a decrease in the water content of vegetation, estimated by the Global Vegetation Moisture Index during the dry period and wet period onset, can be used to identify potential conditions for forest fire occurrence. This study suggests that forest managers should consider implementing prevention strategies that include continuous monitoring of climate and vegetation parameters.
  • ItemOpen Access
    Dengue Climate Variability in Rio de Janeiro City with Cross-Wavelet Transform
    (Scientific Research Publishing, 2022-03) dos Santos Franco, Suellen Araujo; Karam Abi, Hugo; Filho Pereira, Augusto José; da Silva Barreto, Júlio Cesar; Flores Rojas, José Luis; Suazo Angeles, Julio Migue; Panduro Vásquez, Isela Leonor; Peña Sanchez, Cesar Arturo
    Dengue is one of the most prominent tropical epidemic diseases present in the Rio de Janeiro city and Southeast part of Brazil, due to the widespread conditions of occurrence of the dengue vector, the mosquito Aedesaegypti, such as high-temperature days interlaced with afternoon or nocturnal rainstorms in summer. This work has the objective of investigating the relationships between variabilities of the El Niño-South Oscillation (ENSO) and greater epidemics of dengue in Rio de Janeiro city. To accomplish this goal, the analysis and signal decomposition by cross-wavelet transform (WT) was applied to obtain the cross variability associated with variations of power and phase of both signals by characteristic periods and along with the time series. Data considered in the analysis are (the decimal logarithm of normalized value) of the monthly available notifications of dengue worsening, provided by the public health system of Brazil, and the Southern Oscillation Index (SOI) Niño 3.4 data, provided by the National Oceanic and Atmospheric Administration (NOAA), in the period 2000-2017. A maximum cross-wavelet power close to 0.45 was obtained for the representative period of 1 year and also to periods between 3 and 4 years, associated with the positive phase of the SOI index (i.e., La Niña) or with a transition to the positive phase. The evolution of the combined variability of SOI and dengue can be expressed by progressive differences in phase along the time, eventually resulting in yielding phases (i.e., La Niña-Dengue epidemic).
  • ItemRestricted
    ²⁴⁰Pu/²³⁹Pu signatures allow refining the chronology of radionuclide fallout in South America
    (Elsevier, 2022-10-15) Chaboche, Pierre-Alexis; Pointurier, Fabien; Sabatier, Pierre; Foucher, Anthony; Tiecher, Tales; Minella, Jean P.G.; Tassano, Marcos; Hubert, Amélie; Morera Julca, Sergio Byron; Guédron, Stéphane; Ardois, Christophe; Boulet, Béatrice; Cossonnet, Catherine; Cabral, Pablo; Cabrera, Mirel; Chalar, Guillermo; Evrard, Olivier
    Atmospheric nuclear tests (1945–1980) have led to radioactive fallout across the globe. French tests in Polynesia (1966–1974) may influence the signature of fallout in South America in addition to those conducted by USA and former USSR until 1963 in the Northern hemisphere. Here, we compiled the ²⁴⁰Pu/²³⁹Pu atom ratios reported for soils of South America and conducted additional measurements to examine their latitudinal distributions across this continent. Significantly lower ratio values were found in the 20–45° latitudinal band (0.04 to 0.13) compared to the rest of the continent (up to 0.20) and attributed to the contribution of the French atmospheric tests to the ultra-trace plutonium levels found in these soils. Based on sediment cores collected in lakes of Chile and Uruguay, we show the added value of measuring ²⁴⁰Pu/²³⁹Pu atom ratios to refine the age models of environmental archives in this region of the world.
  • ItemRestricted
    Payment for ecosystem services in Peru: Assessing the socio-ecological dimension of water services in the upper Santa River basin
    (Elsevier, 2022-08) Dextre, Rosa María; Eschenhagen, María Luisa; Camacho Hernández, Mirtha; Rangecroft, Sally; Clason, Caroline; Couldrick, Laurence; Morera Julca, Sergio Byron
    Increasing pressures on ecosystems in the Latin American region, as well as the adoption of multilateral conservation commitments, have led to the implementation of instruments that are economic in nature but oriented towards the recovery, conservation, and functioning of ecosystems such as Payment for Ecosystem Services (PES). In the Peruvian Andes, hydro-climatic factors and land-use changes are affecting the capacity of the ecosystems of the glaciated Cordillera Blanca to provide water services, in terms of both quality and quantity, to the main users of the Santa River basin. Thus, this study analyses how the socio-ecological interactions affect, and are affected by, the planned introduction of water-related PES in the Quillcay sub-basin, the most populated sub-basins along the Santa River basin. We use a conceptual model based on the current evolution of the water metabolism approach to integrate into a common language of analysis the multiple dimensions of water: water as an ecological fund, as a service, and as a political asset. To explore the interface of these three domains of analysis we rely on a mixed-method data collection: primary data collection through a stakeholder survey and interviews and a review of information from secondary sources. The result of our case study shows that both the ecological dimension and the social dimension affect on the PES project and vice versa. These complex interactions could result in the design of a mechanism in which not all stakeholders benefit equally. This raises the need to recognise the multidimensional nature of water in the design and implementation of policies, and the importance of identifying processes and barriers which affect the success of these policies without making invisible the direct effect they also have on social-ecological systems.
  • ItemOpen Access
    Diagnosis of the Extreme Climate Events of Temperature and Precipitation in Metropolitan Lima during 1965–2013
    (MDPI, 2022-07-23) Giráldez, Lucy; Silva Vidal, Yamina; Flores Rojas, José Luis; Trasmonte, Grace
    The most extreme precipitation event in Metropolitan Lima (ML) occurred on 15 January 1970 (16 mm), this event caused serious damage, and the real vulnerability of this city was evidenced; the population is still not prepared to resist events of this nature. This research describes the local climate variability and extreme climate indices of temperature and precipitation. In addition, the most extreme precipitation event in ML is analyzed. Extreme climate indices were identified based on the methodology proposed by the Expert Team on Climate Change Detection and Indices (ETCCDI). Some extreme temperature indices highlight an initial trend toward warm conditions (1965–1998); this trend has changed towards cold conditions since 1999, consistent with the thermal cooling during the last two decades in ML (−0.5 °C/decade) and other coastal areas of Peru. The variations of extreme temperature indices are mainly modulated by sea-surface temperature (SST) alterations in the Niño 1 + 2 region (moderate to strong correlations were found). Extreme precipitation indices show trends toward wet conditions after the 1980s, the influence of the Pacific Ocean SST on the extreme precipitation indices in ML is weak and variable in sign. The most extreme precipitation event in ML is associated with a convergence process between moisture fluxes from the east (Amazon region) at high and mid levels and moisture fluxes from the west (Pacific Ocean) at low levels, and near the surface.