The 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 conve...

Although climatologically dry, the western slopes of the southern Andes of Peru (WSA) can experience precipitation extremes (PEs) during the summer (December–February) resulting in great economic and human losses. Generally, WSA has a positive upslope gradient in precipitation, meaning more rain falls at higher elevations, but observations have shown this gradient can become negative with higher rainfall near the coastal cities. In this study we analyse 2000–2019 regional atmospheric patterns associated with different upslope precipitation gradients and PEs in WSA using principal component analysis methods and surface station observations. Results show important changes in the atmospheric circulation patterns during the occurrence of PE events. A prevailing pattern of negative southerly wind anomalies and regional warming of the southeastern Pacific Ocean leads to significant increas...

La agricultura local en los Andes Centrales del Perú es sensible a episodios extremos, por ejemplo, la precipitación intensa asociada a tormentas convectivas perjudican los sembríos por el exceso de agua, mientras que los granizos rompen las hojas de los cultivos cuando alcanzan el suelo. Aquí se estudió la distribución espacial y la estructura vertical de las tormentas convectivas mediante el método del análisis complejo. El área de estudio se fraccionó en 4 sub-áreas (3 áreas sobre los Andes y una que comprende la transición Andes-Amazonía), en los cuales se realizó la estadística de la reflectividad, la intensidad de lluvia y los parámetros microfísicos, determinados usando los sensores del PR-TRMM, el núcleo GPM, y el modelo WRF. Como resultado se tiene que en las regiones de los Andes ocurren sistemas de nubes convectivas más profundas que en la región de transi...

La agricultura local en los Andes Centrales del Perú es sensible a episodios extremos, por ejemplo, la precipitación intensa asociada a tormentas convectivas perjudican los sembrios por el execeso de agua, mientras que los granizos rompen las hojas de los cultivos cuando alcanzan el suelo. Aquí se estudio la distribución espacial y la estructura vertical de las tormentas convectivas mediante el método del análisis complejo. El área de estudio se fraccionó en 4 sub áreas (3 áreas sobre los Andes y una que comprende la transición Andes-Amazonía), en los cuales se realizó la estadística de la reflectividad, la intensidad de lluvia y los parámetros microfísicos, determinados usando los sensores del PR-TRMM, el núcleo GPM, y el modelo WRF. Como resultado se tiene que en las regiones de los Andes ocurren sistemas de nubes convectivas más profundas que en la región de transic...

Proporcionar una mejor estimación de a y b para precipitaciones convencionales (estratiforme y convectiva) en los Andes Centrales del Perú a partir de la relación empírica de Marshall and Palmer, para lo cual se utilizan datos estimados de distintos instrumentos tanto de in situ y por dos radares de frecuencia dual (DPR) que se encuentran abordo del satélite meteorológico núcleo GPM.

In the Central Andes of Peru, convective and stratiform rainfall occurs, frequently associated with convective storms. The raindrop size distributions (RSD), measured by a Parsivel-2 optical disdrometer, were characterized by the variation of their normalized parameters. The RSD dataset includes measurements corresponding to 18 months between 2017 and 2019. As a result, it was found that the mass-weighted mean diameter Dm and the Nw parameter present respectively high and low values, in the interval of 15–20 LST (local standard time), wherein deeper and more active clouds appear. The events including convective rainfall contribute 67.5% of the accumulated total, wherein 92% corresponds to the 15–20 LST interval. It is concluded that the spectral variability of the RSD is strongly controlled by the cloudiness configuration field developing over the west (convection over highlands) and...

La agricultura local en los Andes Centrales del Perú es sensible a episodios extremos, por ejemplo, la precipitación intensa asociada a tormentas convectivas perjudican los sembríos por el exceso de agua, mientras que los granizos rompen las hojas de los cultivos cuando alcanzan el suelo. Aquí se estudió la distribución espacial y la estructura vertical de las tormentas convectivas mediante el método del análisis complejo. El área de estudio se fraccionó en 4 sub-áreas (3 áreas sobre los Andes y una que comprende la transición Andes-Amazonía), en los cuales se realizó la estadística de la reflectividad, la intensidad de lluvia y los parámetros microfísicos, determinados usando los sensores del PR-TRMM, el núcleo GPM, y el modelo WRF. Como resultado se tiene que en las regiones de los Andes ocurren sistemas de nubes convectivas más profundas que en la región de transi...

La distribución del tamaño de las gotas (DSD, por sus siglas en inglés) es un parámetro importante para entender los procesos físicos en la formación de las precipitaciones; por ello, el objetivo de este estudio es entender la microfísica de la precipitación sólida y líquida con el fin de mejorar la estimación de precipitación por radares en la superficie y los satélites. Los resultados muestran que, durante la tarde y noche, entre las 15:00 y 20:00, hora local (HL), las precipitaciones ocurren con partículas que tienen diámetros grandes y una concentración baja. Las precipitaciones, tanto sólida (granizo) como líquida, tienen características microfísicas diferenciadas: la primera tiene dos modas en el promedio del espectro con tamaños más grandes que pueden alcanzar hasta 7 mm de diámetro, mientras que la segunda tiene una sola moda que decae más rápido con el a...

La medición del factor de reflectividad (Z) a través de sensoramiento remoto por radares es de gran interés, ya que a partir de ello se determina la razón de lluvia (R), sin embargo estas mediciones están sujetos a incertidumbre, debido a que para estimar la razón de lluvia en la superficie, el satélite utilizó el valor de Z medida a una altura cercana a la superficie, y considera que Z no varía hasta el suelo. Las estimaciones de R y Z proporcionado por el Dual-frequency Precipitation Radar (DPR) que se encuentra abordo del satélite Global Precipitation Measurement (GPM), ha sido comparado y validado con los datos in situ del disdrómetro óptico y el radar Mira35C en la banda Ka, así mismo para la validación se realizaron experimentos utilizando la técnica de papel del filtro para obtener la Drop Size Distribution (DSD) a partir de 40 muestras para diferentes eventos de ll...

Las precipitaciones convectivas asociadas a tormentas ocurren frecuentemente en los Andes Centrales del Perú. Para estudiar estos eventos se determinaron estimadores estadísticos de la reflectividad tri-dimensional, la intensidad de lluvia y parámetros microfísicos usando la información de radares abordo en los satélites del TRMM y el núcleo GPM. Como resultado se encontró que en las regiones de los Andes ocurren sistemas de nubes más profundas que en la región de transición Amazonia-Andes. De tal manera la diferencia del promedio vertical de la reflectividad presenta valores de alrededor de 5 dBZ entre ambas regiones. El ciclo diurno de la lluvia también es diferente, ya que llueve preferentemente en los intervalos 13-23 horas local y 18-06 hora local respectivamente. Los porcentajes de ocurrencia de precipitación convectiva y estratiforme en las áreas de los Andes son 30%...

This dataset includes data obtained at the Atmospheric Microphysics and Radiation Laboratory (LAMAR) of the Huancayo Observatory (12.04° S, 75.32° W, 3313 m ASL). Two Parsivel2 and two tipping bucket rain gauges are used in this dataset which are operating together since 2018. Data is given in NetCDF format, including two types of files, one NetCDF for precipitation totals and another which contains Parsivel2 data. This data set was collected in the complex topography conditions of the tropical Andes, and its potential use is to study the microphysics of orographic rainfall, atmospheric models and rainfall estimation algorithms.

We acknowledge financial support from the International Foundation for Science, Sweden, Concejo Nacional de Ciencia y Tecnologia CONCYTEC, Peru, and the Wellcome Trust, U.K

The aim of the present study is to analyze the triggering mechanisms of three thunderstorms (TSs) associated with severe rainfall, hail and lightening in the tropical central Andes of Peru, specifically above the Huancayo observatory (12.04º S, 75.32º W, 3313 m a.s.l.) located in the Mantaro valley during the spring-summer season (2015–2016). For this purpose, we used a set of in-situ pluviometric observations, satellite remote sensing data, the Compact Meteorological Ka-Band Cloud Radar (MIRA-35C), the Boundary Layer Tropospheric Radar and downscaling model simulations with the Weather Research and Forecasting (WRF) Model (resolutions: 18 km, 6 km and 2 km), and the Advance Regional Prediction System (ARPS) (resolution: 0.5 km) models in order to analyze the dynamic of the atmosphere in the synoptic, meso and local scales processes that control the occurrence of the three TS events....

In 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, transfor...

Hailstorms, 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 p...

Hailstorms, 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 ...

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 present study explores the cloud microphysics (MPs) impact on the simulation of two convective rainfall events (CREs) over the complex topography of Andes mountains, using the Weather Research and Forecasting- Advanced Research (WRF-ARW) model. The events occurred on December 29 2015 (CRE1) and January 7 2016 (CRE2). Six microphysical parameterizations (MPPs) (Thompson, WSM6, Morrison, Goddard, Milbrandt and Lin) were tested, which had been previously applied in complex orography areas. The one-way nesting technique was applied to four domains, with horizontal resolutions of 18, 6, and 3 km for the outer ones, in which cumulus and MP parameterizations were applied, while for the innermost domain, with a resolution of 0.75 km, only MP parameterization was used. It was integrated for 36 h with National Centers for Environmental Prediction (NCEP Final Operational Global Analysis (NFL) i...

Present study comes under the project MAGNET-IGP: Strengthening the research line in physics and microphysics of the atmosphere (Agreement No 010-2017-FONDECYT) This work was done using instruments of the Laboratory of Physics, Microphysics and Radiation (LAMAR) and computational resources, HPC-Linux -Cluster, from Laboratorio de Dinamica de Fluidos Geofisicos Computacionales at Instituto Geofisico del Peru (grants 101-2014-FONDECYT, SPIRALES2012 IRD-IGP, Manglares IGP-IDRC, PP068 program).We also thank Mr. Luis Suarez Salas for the support of LAMAR instruments.

This study presents an in-depth analysis of precipitation patterns, surface energy balance (SEB) components, and atmospheric vertical gradients (AVG) in the Huancayo Geophysical Observatory (HYGO) situated in an agricultural region inside the Mantaro valley within the central Andes of Peru, utilizing data from January 2018 to April 2022 and climatic-scale data from 1965 to 2018. Our findings reveal distinct daily and seasonal precipitation patterns, with peak occurrences in the late afternoon and early evening hours, and a pronounced seasonal variation aligning with dry and rainy periods. Analysis of 21 intense precipitation events linked to convective activity offers crucial insights for weather forecasting and disaster preparedness. These events were identified using in situ gauge pluviometers, the MIRA-35c vertical profiler radar and GPM-IMERG rainfall products. The turbulent energy f...