The ability of the WRF-ARW (Weather Research and Forecasting-Advanced Research WRF) model to forecast extreme rainfall in the Central Andes of Peru is evaluated, using observations from stations located in the Mantaro basin and GOES (Geostationary Operational Environmental Satellite) images. The evaluation analyzes the synoptic conditions averaged over 40 extreme event cases, and considers model simulations organized in 4 nested domains. Simulation results show that the Weather Research and Forecasting (WRF) model underestimates rainfall totals in approximately 50–60% of cases. The analysis of two case studies shows that the underestimation by the model is probably due to three reasons: inability to generate convection in the upstream Amazon during early morning hours, limitations on describing mesoscale processes that lead to vertical movements capable of producing extreme rainfall, a...

The ability of the WRF-ARW (Weather Research and Forecasting-Advanced Research WRF) model to forecast extreme rainfall in the Central Andes of Peru is evaluated in this study, using observations from stations located in the Mantaro basin and GOES (Geostationary Operational Environmental Satellite) images. The evaluation analyzes the synoptic conditions averaged over 40 extreme event cases, and considers model simulations organized in 4 nested domains. We first establish that atypical events in the region are those with more than 27 mm of rainfall per day when averaging over all the stations. More than 50% of the selected cases occurred during January, February, and April, with the most extreme occurring during February. The average synoptic conditions show negative geopotential anomalies and positive humidity anomalies in 700 and 500 hPa. At 200 hPa, the subtropical upper ridge or “Bol...

The work carried out a characterization of tropospheric vertical profiles in rainy and dry seasons by behavior of thermodynamic indices obtained with the WRF model for the period January 2018–March 2019 on the central Andes of Peru and its relationship with rainfall in the region. A case study was also analyzed using sounding observation data. The precipitation observed were taken from 8 meteorological stations located in the Mantaro basin belonging to the National Meteorological Service of Peru. As a results, it was found that the behavior of the thermodynamic parameters responds to the general characteristics of each period. The level of condensation was always higher in the dry period, in which the lower troposphere was also more stable. The KI, TT, Sweat and CAPE indices were always higher in the rainy season, as was water vapor mixing ratio. The vertical shear was mostly higher in...

The study evaluated the sensitivity of the precipitation forecast in the central Andes of Peru of Weather Research and Forecasting (WRF) model to change the planetary boundary layer (PBL) schemes. In that region is located the Mantaro basin, which is one of the most important in the region. Here, the rainfall is very important to the agriculture and to the reserves of drinking water. The simulations were carried out with ten PBL schemes for 19 days in January, February, and March, between 2009 and 2012. Based on the statistical analysis (model vs. observation), the more efficient schemes were determined and analyses of the vertical profiles of some variables are shown. As a result, the schemes that most helped the model in rainfall forecasting were MYNN3 (general and north sector of the basin), Bou-Lac (central sector) and Bretherton-Park (southern sector). The model generally overestima...

A sensitivity study of the performance of the Weather Research and Forecasting regional model (WRF, version 3.7) to the use of different microphysics, cumulus, and boundary layer parameterizations for short- and medium-term precipitation forecast is conducted in the Central Andes of Peru. Lin-Purdué, Thompson, and Morrison microphysics schemes were tested, as well as the Grell–Freitas, Grell 3d, and Betts–Miller–Janjic cumulus parameterizations. The tested boundary layer schemes were the Yonsei University and Mellor–Yamada–Janjic. A control configuration was defined, using the Thompson, Grell–Freitas, and Yonsei University schemes, and a set of numerical experiments is made, using different combinations of parameterizations. Data from 19 local meteorological stations and regional and global gridded were used for verification. It was concluded that all the configurations over...

A sensitivity study of the performance of the Weather Research and Forecasting regional model (WRF, version 3.7) to the use of different microphysics, cumulus, and boundary layer parameterizations for short- and medium-term precipitation forecast is conducted in the Central Andes of Peru. Lin-Purdué, Thompson, and Morrison microphysics schemes were tested, as well as the Grell–Freitas, Grell 3d, and Betts–Miller–Janjic cumulus parameterizations.

En esta investigación se decidió determinar la relación existente entre las variables: Obras de contingencia y nivel de riesgos de seguridad y salud, siendo la unidad de población 55 pobladores en el centro poblado de Chiuchin, escogidos para la presente tesis en base a la pobreza extrema en la que viven y la exposición a la vulnerabilidad existente; utiliza el tipo de investigación aplicada, un diseño no experimental, nivel de investigación correlacional y un enfoque cuantitativo. Se desarrollo sustancialmente el objetivo general, el cual fue determinar la relación existente entre la Obras de contingencia y el nivel de riesgos de seguridad y salud en el río de Chiuchin, cuyas dimensiones analizadas fueron acondicionamiento de terreno, operaciones en gavión y trabajos en piedra para la variable independiente, y para la variable dependiente las dimensiones analizadas fueron val...

Se construye un modelo estadístico de pronóstico mensual de precipitaciones para Perú, basado en la relación de varios índices climáticos oceánicos y atmosféricos, así como de los índices de la oscilación de Madden-Julian, con la variabilidad estacional de la precipitación en el país, a inicializar en el mes de junio de cada año. Se aplicó la técnica de regresión lineal entre los índices y la precipitación grillada de la fuente de datos de PISCO para el período diciembre marzo, meses que corresponden a la estación lluviosa en Perú. El modelo se construyó con datos correspondientes al período 1981-2016 y se verificó con los registros de precipitación correspondientes a los años 2017-2022 para 15 zonas dentro de la costa, sierra y selva. El valor del error medio absoluto (MAE, por sus siglas en inglés) fue mejor para la selva, con excepción de los pronósticos ...

Se muestran dos modelos estadísticos de pronóstico, uno para el Índice Costero El Niño (ICEN) y el otro para el Índice Niño Oceánico (ONI, por sus siglas en inglés), los que se enfocan para la temporada de lluvias en Perú, usando datos del período 1975-2016. Como resultado, se obtuvieron dos modelos con versiones a inicializar en los meses de julio, agosto, septiembre y octubre. Los predictores más informativos para los primeros 2-3 meses de pronóstico fueron el comportamiento de los propios índices en meses anteriores, la profundidad de la isoterma de 20 ºC y los vientos zonales en superficie. Los índices climáticos juegan un papel más importante en plazos más largos. Para el ICEN, los vientos zonales resultaron más informativos en el Pacífico este; mientras que, para el ONI, los vientos zonales en el Pacífico oeste. Los coeficientes de correlación (R) de las ecuac...

En el presente trabajo, se llevó a cabo una investigación para evaluar cómo el modelo WRF pronostica la lluvia en los Andes centrales peruanos. Para ello, las salidas numéricas se comparan con datos de observación “in situ” de 19 estaciones en la región (Figura 1c), así como con datos satelitales. La mayor parte de la lluvia en el Perú se concentra en el período comprendido entre los meses de septiembre y abril (Silva et al., 2008), definiendo una marcada estacionalidad, que cuenta con una estación seca entre mayo y agosto (Aceituno, 1989; Vuille, 2008). En los Andes centrales peruanos, la lluvia juega un papel económico importante, ya que el 71% de la tierra cultivable en la cuenca del Mantaro, una de las más importantes de la zona, depende de ella para los cultivos.

A sensitivity study of the performance of the Weather Research and Forecasting regional model (WRF, version 3.7) to the use of different microphysics, cumulus, and boundary layer parameterizations for short- and medium-term precipitation forecast is conducted in the Central Andes of Peru. Lin-Purdué, Thompson, and Morrison microphysics schemes were tested, as well as the Grell–Freitas, Grell 3d, and Betts–Miller–Janjic cumulus parameterizations. The tested boundary layer schemes were the Yonsei University and Mellor–Yamada–Janjic. A control configuration was defined, using the Thompson, Grell–Freitas, and Yonsei University schemes, and a set of numerical experiments is made, using different combinations of parameterizations. Data from 19 local meteorological stations and regional and global gridded were used for verification. It was concluded that all the configurations over...

The ability of the WRF-ARW (Weather Research and Forecasting-Advanced Research WRF) model to forecast extreme rainfall in the Central Andes of Peru is evaluated in this study, using observations from stations located in the Mantaro basin and GOES (Geostationary Operational Environmental Satellite) images. The evaluation analyzes the synoptic conditions averaged over 40 extreme event cases, and considers model simulations organized in 4 nested domains. We first establish that atypical events in the region are those with more than 27 mm of rainfall per day when averaging over all the stations. More than 50% of the selected cases occurred during January, February, and April, with the most extreme occurring during February. The average synoptic conditions show negative geopotential anomalies and positive humidity anomalies in 700 and 500 hPa. At 200 hPa, the subtropical upper ridge or “Bol...

The main objective of the research is to evaluate the response of the WRF model to the domains and resolutions that are used in complex orographic conditions like the central Andes of Peru for the forecast of short- and medium-term rainfall. To do this, the model was configured with four domains and the verifications were made using data from meteorological stations located within the study area and TRMM data. Experiments were conducted for nine 10-day periods of rainy days, five cases of extreme rainfall, and one event with hail fall on the region. In general, the model overestimates precipitation, but, in the five cases of extreme rainfall, and in the case of the hailstorm, underestimation was observed, so it is not accurate to assert in an absolute way that WRF overestimates precipitation in the study region. It was observed that the 3-km domain simulate effectively the accumulated ra...

In this study, the results were evaluated of the application of the meteorological model Weather Research and Forecasting (WRF) in 103 days where extreme precipitation events (90th percentile) occurred within the Mantaro River basin. The WRF atmospheric model was used for four areas through nesting multiple, and spatial resolutions of 18, 6, 3 and 0.75 km, respectively, were obtained. Extreme precipitation forecasts were made and the effectiveness of the numerical outputs was evaluated, using observed data {\emph in-situ}, through the SENAMHI weather station network and satellite information. The values of statistical estimators show that the model tends to underestimate the rainfall data in many cases and overestimates it in others, having limitations in representing the spatial variability of the observed data. Accumulated precipitation satellite data always overestimates precipitation...

Las lluvias extremas ocurridas en el verano austral del 2017 en el centro y norte del Perú, han evidenciado que aún falta entender los procesos dinámicos que ocurren en esta zona, ya que no pudo ser pronosticado con antelación. Por otro lado, las ciudades costeras de Piura, Chiclayo, Trujillo y Lima, que tienen gran densidad poblacional y con alto desarrollo económico, están diseñadas para un clima de costa sin muchas lluvias. En la presente investigación, se evalúa la capacidad de respuesta del Modelo de Investigación y Pronóstico del Tiempo-WRF, por sus siglas en inglés (Skamarock, et al., 2008), para reproducir las lluvias extremas ocurridas en el verano de 2017, en las regiones costeras del centro y norte del Perú, vertiente del Pacífico, 3°S-10°S y 76°W-82°W (VNP). En los avances de esta investigación, se identificaron los periodos de lluvia mayores al percentil 9...

The characteristics of the precipitation under the influence of topography and surface wind flow are investigated over South America. Here the precipitating cloud systems (PCSs) are identified using the Global Precipitation Measurement Precipitation Radar (GPM-PR) data, which provides the three dimensional radar reflectivity factor (Ze), rain rate, drop size and droplet concentration. For each PCSs the surface wind properties are estimated using European Center for Medium-Range Weather Forecast Interim data. Based on the direction of surface flow the PCSs are classified into five categories. Over the South America the near surface wind flow transports the moisture from Amazon basin to east flank of Andes and validated here. The directional surface flow decides the occurrences of the PCSs, as upslope consists of the higher and larger PCSs at the peak of Andes compared to downslope flow. T...

This study assesses the influence of PM10 on the optical thickness of aerosols in the central Andes of Peru, in addition to analyzing and establishing their circulation patterns from July to October 2017. This particular period is considered herein because the largest biomass burning events are usually recorded during these months. The regional meteorological-chemistry transport model WRF-Chem (version 3.7) was used with the Fire Inventory from NCAR (FINN) fire emissions dataset and aerosol optical depth (AOD) data from the Aerosol Robotic Network monitoring network (AERONET), which has a CIMEL sun photometer located at the Huancayo Observatory, the most important city in the central highlands of Peru. The simulation used a single domain with a grid size of 18 km and 32 vertical levels. Results showed an increase in PM10 concentrations with an increase in the number of fire outbreaks and...

In the present study, five-year of precipitation features (PFs) datasets, based on Global Precipitation Measurement (GPM), are used to investigate the global and regional characteristics of extreme rainfall events (EREs). The EREs are defined based on the PFs area, depth (maximum height of radar reflectivity), and the rain rate and called them largest, deepest, and intense EREs, respectively.

This study assesses the influence of PM₁₀ on the optical thickness of aerosols in the central Andes of Peru, in addition to analyzing and establishing their circulation patterns from July to October 2017. This particular period is considered herein because the largest biomass burning events are usually recorded during these months. The regional meteorological-chemistry transport model WRF-Chem (version 3.7) was used with the Fire Inventory from NCAR (FINN) fire emissions dataset and aerosol optical depth (AOD) data from the Aerosol Robotic Network monitoring network (AERONET), which has a CIMEL sun photometer located at the Huancayo Observatory, the most important city in the central highlands of Peru. The simulation used a single domain with a grid size of 18 km and 32 vertical levels. Results showed an increase in PM₁₀ concentrations with an increase in the number of fire outbr...

In the present study, five-year of precipitation features (PFs) datasets, based on Global Precipitation Measurement (GPM), are used to investigate the global and regional characteristics of extreme rainfall events (EREs). The EREs are defined based on the PFs area, depth (maximum height of radar reflectivity), and the rain rate and called them largest, deepest, and intense EREs, respectively. The EREs are divided into top 10%, 1%, 0.1%, and 0.01% based on their frequency of occurrences. It is observed that occurrences of EREs belonging to less than top 0.01% EREs follow the tropical rainfall climatology over the tropics based on all the parameters. Subtropical oceanic areas consist of a higher frequency of largest EREs, whereas tropical land areas consist of the higher number of deepest EREs. The most intense EREs (top 0.01%) are uniformly distributed over tropical areas and subtropical ...