Browsing by Author "Espinoza, Jhan-Carlo"
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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 Cambios de la precipitación en el centro del Perú por efectos de la deforestación amazónica(Instituto Geofísico del Perú, 2023-07) Saavedra Huanca, Miguel; Junquas, Clementine; Espinoza, Jhan-Carlo; Silva Vidal, YaminaEste trabajo analiza el impacto de la deforestación amazónica en la precipitación de los Andes centrales del Perú durante la temporada húmeda, haciendo uso del modelo atmosférico Weather Research and Forecasting Model (WRF, por sus siglas en inglés). La región de estudio abarca la ciudad de Lima y localidades ubicadas en la cuenca del río Mantaro, de suma importancia debido a su elevada densidad poblacional. En tal sentido, se configuró el modelo WRF para la región de estudio bajo dos escenarios: uno con la Amazonía sin deforestación y otro con un 40 % de deforestación. Debido a la compleja topografía de la región se utilizaron múltiples dominios de alta resolución en el modelo. Los resultados preliminares muestran que, como consecuencia de la deforestación del 40 % en la Amazonía, se prevén cambios relativos netos en la precipitación en la cuenca del río Mantaro y en las zonas altas de la pendiente oeste de los Andes que podrían alcanzar una reducción de 5 % y un aumento de 5 %, respectivamente. En el futuro, estos cambios podrían tener relevancia para la gestión del agua en la región.Item Restricted Decadal variability in the austral summer precipitation over the Central Andes: Observations and the empirical-statistical downscaling model(Royal Meteorological Society, 2022-09-16) Sulca Jota, Juan Carlos; Takahashi, Ken; Tacza, José; Espinoza, Jhan-Carlo; Dong, BoThe decadal variability in summer precipitation over the Central Andes (10°–30°S) is investigated from 1921 to 2010 using low-pass filtered time series of the central and eastern El Niño–Southern Oscillation (ENSO) Pacific (C and E) indices, the South Pacific Convergence Zone (SPCZ) index, the Atlantic SST indices, Atlantic Multidecadal Oscillation (AMO) index, North Atlantic Oscillation (NAO) index, and ERA-20C reanalysis. Additionally, an empirical-statistical downscaling (ESD) model was built. A rotated empirical orthogonal function (REOF) analysis shows that the first leading mode of precipitation (RPC1) represents 38.2% of the total decadal variance. RPC2, RCP3, and RPC4 represent 18.8, 12.8, and 9.7% of the total decadal variance, respectively. Furthermore, RPC1 features highest loadings over most of the region. RPC2 features a dipole of highest loadings over the southernmost Bolivian Altiplano and lowest loadings over the northwestern Argentinian Andes. Conversely, RPC3 presents highest loadings over the eastern-central Bolivian Altiplano and northwestern Argentinian Andes. RPC4 features highest loadings over the southern Bolivian Andes. RPC1 and RPC3 wet summers are associated with moisture transport from the Amazon basin, but RPC1 features the strengthening upper-level Bolivian high-Nordeste low system over South America. Conversely, RPC2 and RPC4 wet summers are associated with local processes induced by southward displacement of the South Atlantic Convergence Zone and warm sea surface temperature (SST) anomalies over the Indian Ocean, respectively. According to the ESD model, the decadal variability in the central and eastern Pacific (CP and EP) and Atlantic Ocean reproduces the decadal component of the DJF precipitation over most of the Central Andes.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 Restricted Impacts of topography and land use changes on the air surface temperature and precipitation over the central Peruvian Andes(Elsevier, 2020-04) Saavedra Huanca, Miguel; Junquas, Clementine; Espinoza, Jhan-Carlo; Silva Vidal, YaminaThis paper focuses on the representation of the air surface temperature and precipitation using high spatiotemporal simulations (3 km–1 h) of the WRF3.7.1 model in the central Peruvian area. It covers, from east to west, the coastal zone, the western slope of the Andes, the Andean Mantaro basin (500–5000 masl), and the Andes-Amazon transition region in the eastern Andes. The study covers the January months from 2004 to 2008. Three experiments were conducted using different topography and land use data sources: (1) a control simulation using the default WRF topography and land use datasets from the United States Geological Survey (USGS); (2) a simulation changing only the topography by using the SRTM topography dataset; and (3) a simulation changing the land use data of (2) by a new dataset adapted from Eva et al. (2004). SRTM topography performed better than the control simulation for representing the actual altitudes of 57 meteorological stations that were used for precipitation and surface air temperature data. As a result, the simulations of experiments (2) and (3) produced lower bias values than that of (1). Topography change (experiment (2)) showed improvements in temperature bias that were directly associated with linear modifications of -5.6 and -6.7 °C∙km⁻¹ in minimum and maximum temperature, respectively. Increasing (decreasing) precipitation with topography or land use change was clearly controlled by changes in the moisture flux patterns and its convergence (divergence) in the Andes-Amazon transition. On the western slope, precipitation increase could be associated with the increase in easterly flow by the smaller altitudes of the Andes mountains in SRTM topography and by increasing evaporation with new land use. Inside the Mantaro Basin, low level moisture flux seems to control the rainfall changes. Overall, relative changes (positive or negative) in precipitation due to topography or land use change could reach values above 25%.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 Simulaciones de la precipitación de verano por modelos climáticos regionales de CORDEX en la zona de transición Andes-Amazonía(Instituto Geofísico del Perú, 2023-02) Gutiérrez, Ricardo A.; Junquas, Clémentine; Armijos Cardenas, Elisa Natalia; Sörensson, A. A.; Espinoza, Jhan-CarloEl presente avance de investigación evalúa el realismo de la climatología histórica (1981-2005) de la precipitación de verano en la zona de transición Andes-Amazonía a partir de las simulaciones del experimento regional coordinado de reducción de escala (CORDEX, por sus siglas en inglés) para Sudamérica. Los resultados preliminares muestran que no habría una relación aparente entre la performance del modelo y la resolución espacial en cuanto a la reproducción de las climatologías de precipitación, cuando se esperaría que los modelos tengan un mejor rendimiento, es decir, reproduzcan mejor las precipitaciones al tener una resolución espacial más alta o más fina. En conclusión, será necesaria la aplicación de modelos regionales de resolución espacial más fina y realizar experimentos de sensibilidad con diferentes parametrizaciones físicas para lograr mejorar el realismo de los patrones espaciales de la precipitación orográfica sobre la región de estudio.Item Open Access Variabilidad decenal de las lluvias de los Andes centrales en el último siglo(Instituto Geofísico del Perú, 2023-02) Sulca Jota, Juan Carlos; Takahashi, Ken; Tacza, José; Espinoza, Jhan-Carlo; Dong, BoSe investiga la variabilidad decenal de la precipitación de los Andes centrales (10-30° S, AC) durante el verano entre 1921 y 2010 mediante la aplicación de un filtro pasabanda para retener dicha variabilidad en las series mensuales de diversos índices climáticos predictores del Pacífico central y oriental de El Niño-Oscilación del Sur (C y E), los índices de la temperatura superficial del mar (TSM) del Atlántico y el reanálisis ERA-20C. Con estos se construye un modelo de regresión lineal múltiple (MRL, por sus siglas en inglés) para predecir la variabilidad de las lluvias en los Andes centrales basado en el análisis decenal de función ortogonal empírica rotada (REOF, por sus siglas en inglés). El primer modo REOF de precipitación (RPC1) representa el 38.2 % de la varianza decenal total, mientras que RPC2, RCP3 y RPC4 representan el 17.4 %, 12.7 % y 9.7 %, respectivamente. El RPC1 presenta las señales más altas sobre la mayor parte de los AC. RPC2 presenta un dipolo de señales positivas sobre el extremo sur del Altiplano boliviano y las señales negativas sobre los Andes argentinos noroccidentales. En contraste, RPC3 presenta las señales más altas sobre el Altiplano boliviano central-oriental y los Andes argentinos noroccidentales. RPC4 presenta las señales más altas sobre los Andes del sur de Bolivia. Los veranos húmedos de RPC1 están asociados con el transporte de humedad proveniente de la Amazonia, que se debe al fortalecimiento del sistema Alta de Bolivia- Baja del Noreste sobre América del Sur en los niveles troposféricos altos (200 hPa). El MRL revela que la variabilidad decenal del Pacífico central y oriental (PC y PE) y del océano Atlántico son buenos predictores del primer modo de la componente decenal de la precipitación de verano de los Andes centrales (RPC1).