The rainy season in the Southern Peruvian Andes: A climatological analysis based on the new Climandes index

The rainy season is of high importance for livelihoods in the Southern Peruvian Andes (SPA), especially for agriculture, which is mainly rain fed and one of the main income sources in the region. Therefore, knowledge and predictions of the rainy season such as its onset and ending are crucial for planning purposes. However, such information is currently not readily available for the local population. Moreover, an evaluation of existing rainy season indices shows that they are not optimally suited for the SPA and may not be directly applicable in a forecasting context. Therefore, we develop a new index, named Climandes index, which is tailored to the SPA and designed to be of use for operational monitoring and forecasting purposes. Using this index, we analyse the climatology and trends of the rainy season in the SPA. We find that the rainy season starts roughly between September and January with durations between 3 and 8 months. Both onset and duration show a pronounced northeast-southwest gradient, regions closer to the Amazon Basin have a considerably longer rainy season. The inter-annual variability of the onset is very high, that is, 2–5 months depending on the station, while the end of the rainy season shows a much lower variability (i.e., 1.5–3 months). The spatial patterns of total precipitation amount and dry spells within the rainy season are only weakly related to its timing. Trends in rainy season characteristics since 1965 are mostly weak and not significant, but generally indicate a tendency towards a shortening of the rainy season in the whole study area due to a later onset and an increase in precipitation sums during the rainy season in the northwestern study area

Influencia de la niña Modoki en las lluvias de otoño sobre el Ecuador y el norte del Perú

"El Niño Oscilación del Sur (ENOS) es un modo natural de variabilidad del sistema climático acoplado océano-atmósfera y surge de las interacciones aire-mar que tienen lugar en el Pacífico Tropical. Debido a esta interacción, es preciso analizar ambas componentes para el monitoreo de este evento. En SENAMHI (2015) se propuso una metodología para monitorearlo, en donde se analizaron las variaciones conjuntas del océano y la atmósfera en el Pacífico ecuatorial usando una variable para cada uno de estos componentes. Este esquema de propuesta de monitoreo fue basado en el mecanismo de Bjerknes. En el presente informe se plantea la ligera modificación de los umbrales para el reconocimiento de los eventos El Niño/ La Niña...... Por otro lado, una de las herramientas más utilizadas para el pronóstico del ENOS son los modelos climáticos. Es así que en el presente trabajo se explica la implementación de un sistema en el que se puedan analizar los pronósticos mensuales del modelo CFSv2 de las variables ATSM3.4 e IOSec de modo que al esquema de monitoreo planteado por SENAMHI (2015), se le puedan adicionar los pronósticos mensuales realizados por este modelo". -- Introducción

Pronóstico de sequías meteorológicas para el departamento de Puno, Perú

Las sequías meteorológicas, en las que se centra este estudio, se definen como el período temporal de sequedad expresado en términos de características atmosféricas, tales como una desviación de la precipitación de un promedio o de un periodo normal. Todos los tipos de sequía se originan por una deficiencia de precipitación, aunque otros factores como vientos fuertes, altas temperaturas, baja humedad relativa y condiciones locales pueden exacerbar la severidad de estas (Wilhite y Glantz, 1985; Wilhite et al., 2014; OMM, 2018). Su duración e intensidad generan consecuencias de importantes pérdidas económicas y distorsiones en las actividades de las comunidades rurales y urbanas. Los efectos negativos abarcan la pérdida de cultivos, mortandad pecuaria, proliferación de plagas y enfermedades. Ello afecta en especial a los pequeños productores agrarios, así como a las poblaciones urbanas y a la producción de energía eléctrica. Como se señaló, la principal causa de cualquier sequía es la ausencia de lluvia, en particular durante un tiempo prolongado, principalmente, antes y durante el verano. Esta notable reducción, asociada a varios días secos consecutivos, que aparecen con mayor frecuencia en los últimos diez días previos a la época de sembrío y durante el sembrío, pueden causar daños a la producción agrícola. El área de afectación comprende a gran parte del sur del Perú y se desarrolla con un mayor impacto en Puno. Entre los factores que influyen en los daños ocasionados por las sequías, se encuentran la distribución espacial y la intensidad, la cantidad de agua almacenada en el suelo y en los reservorios de provisión de agua en relación con la demanda, y al uso del agua por parte de los cultivos y la población (Ministerio del Ambiente [MINAM], 2016)

Verificación de los pronósticos estacionales de precipitación a nivel nacional para la temporada de lluvias 2016-2017

Los pronósticos estacionales de precipitación son uno de los servicios que brinda la Subdirección de Predicción Climática (SPC) del Servicio Nacional de Meteorología e Hidrología del Perú (SENAMHI); este servicio se realiza a nivel nacional y mediante un conceso previo con los profesionales involucrados. Sin embrago, es importante saber si estos pronósticos probabilísticos acertaron en las categorías “Bajo”, “Normal” y “Superior” en cada una de las estaciones meteorológicas que conforman la red a nivel nacional del SENAMHI. Por tal motivo, la verificación de estos pronósticos es importante porque brinda información acerca de la cantidad de aciertos y desaciertos permitiendo implementar estrategias para mejorar el pronóstico. El objetivo que guía este estudio es la de verificar a nivel nacional los pronósticos de precipitación en la temporada de lluvias 2016-2017. Para ello, se utiliza el software Climate Predictability Tool (CPT) que permite realizar los pronósticos en base a áreas predictoras y a una serie mensual de datos observados que serán pronosticados en las categorías “Bajo”, “Normal” y “Superior” a escala de tiempo trimestral. Luego, se utiliza el script desarrollado que facilita todo el proceso de cálculo y elaboración de mapas, lo que permite implementar el proceso de la verificación de manera operativa

Análisis del comportamiento de las temperaturas extremas del aire en la costa peruana – abril 2022. Informe Técnico

El servicio Nacional de Meteorología e Hidrología del Perú – SENAMHI, a través de la Subdirección de Predicción Climática (SPC) de la Dirección de Meteorología y Evaluación Ambiental Atmosférica (DMA) y en el marco de sus funciones y competencias, realiza de manera permanente la vigilancia del clima en el territorio peruano, siendo el monitoreo de las temperaturas del airea el aspecto más relevante de esta actividad durante las estaciones de otoño e invierno, con énfasis en el monitoreo de eventos extremos para aplicaciones en la gestión de riesgo de desastres, principalmente. Por ello, el presente informe analiza el comportamiento de las temperaturas máximas y mínimas en la región costera en lo que va del otoño 2022, e indica que los descensos de las temperaturas extremas del aire que se vienen presentando en la costa peruana forman parte del comportamiento estacional y, a su vez, se ven intensificados por la persistencia de anomalías negativas de la temperatura superficial del mar adyacente. Se espera que para el trimestre abril – junio 2022, que abarca la temporada de otoño, las condiciones térmicas se presenten por debajo de lo normal en la costa central y sur

Assessment of ECMWF SEAS5 seasonal forecast performance over South America

Seasonal predictions have a great socioeconomic potential if they are reliable and skillful. In this study, we assess the prediction performance of SEAS5, version 5 of the seasonal prediction system of the European Centre for Medium-Range Weather Forecasts (ECMWF), over South America against homogenized station data. For temperature, we find the highest prediction performances in the tropics during austral summer, where the probability that the predictions correctly discriminate different observed outcomes is 70%. In regions lying to the east of the Andes, the predictions of maximum and minimum temperature still exhibit considerable performance, while farther to the south in Chile and Argentina the temperature prediction performance is low. Generally, the prediction performance of minimum temperature is slightly lower than for maximum temperature. The prediction performance of precipitation is generally lower and spatially and temporally more variable than for temperature. The highest prediction performance is observed at the coast and over the highlands of Colombia and Ecuador, over the northeastern part of Brazil, and over an isolated region to the north of Uruguay during DJF. In general, Niño-3.4 has a strong influence on both air temperature and precipitation in the regions where ECMWF SEAS5 shows high performance, in some regions through teleconnections (e.g., to the north of Uruguay). However, we show that SEAS5 outperforms a simple empirical prediction based on Niño-3.4 in most regions where the prediction performance of the dynamical model is high, thereby supporting the potential benefit of using a dynamical model instead of statistical relationships for predictions at the seasonal scal

Meteorological factors and childhood diarrhea in Peru, 2005–2015: a time series analysis of historic associations, with implications for climate change

Background: Global temperatures are projected to rise by ≥2 °C by the end of the century, with expected impacts on infectious disease incidence. Establishing the historic relationship between temperature and childhood diarrhea is important to inform future vulnerability under projected climate change scenarios. Methods: We compiled a national dataset from Peruvian government data sources, including weekly diarrhea surveillance records, annual administered doses of rotavirus vaccination, annual piped water access estimates, and daily temperature estimates. We used generalized estimating equations to quantify the association between ambient temperature and childhood (< 5 years) weekly reported clinic visits for diarrhea from 2005 to 2015 in 194 of 195 Peruvian provinces. We estimated the combined effect of the mean daily high temperature lagged 1, 2, and 3 weeks, in the eras before (2005–2009) and after (2010–2015) widespread rotavirus vaccination in Peru and examined the influence of varying levels of piped water access. Results: Nationally, an increase of 1 °C in the temperature across the three prior weeks was associated with a 3.8% higher rate of childhood clinic visits for diarrhea [incidence rate ratio (IRR): 1.04, 95% confidence interval (CI): 1.03–1.04]. Controlling for temperature, there was a significantly higher incidence rate of childhood diarrhea clinic visits during moderate/strong El Niño events (IRR: 1.03, 95% CI: 1.01–1.04) and during the dry season (IRR: 1.01, 95% CI: 1.00–1.03). Nationally, there was no evidence that the association between temperature and the childhood diarrhea rate changed between the pre- and post-rotavirus vaccine eras, or that higher levels of access to piped water mitigated the effects of temperature on the childhood diarrhea rate. Conclusions: Higher temperatures and intensifying El Niño events that may result from climate change could increase clinic visits for childhood diarrhea in Peru. Findings underscore the importance of considering climate in assessments of childhood diarrhea in Peru and globally, and can inform regional vulnerability assessments and mitigation planning efforts

Twinning SENAMHI and MeteoSwiss to co-develop climate services for the agricultural sector in Peru

The development and dissemination of weather and climate information is crucial to improve people's resilience and adaptability to climate variability and change. The impacts of climate variability and change are generally stronger for disadvantaged population groups due to their limited adaptive and coping capacities. For instance, smallholder farmers living in remote areas such as the southern Peruvian Andes suffer strongly from adverse weather and climatic events such as droughts or frost. The project Climandes aimed at providing high-quality climate services in support of the agricultural sector in southern Peru by implementing the guidelines of the Global Framework for Climate Services (GFCS). In Climandes, a two-fold challenge was tackled: the co-development of climate services by building up a continuous dialogue between the information provider (in this case the Peruvian national meteorological and hydrological service (NMHS)) and potential users; and the production of climate services through international cooperation. To this end, the NMHSs of Peru (SENAMHI) and Switzerland (MeteoSwiss) worked closely together to tackle issues ranging from the treatment of climate data to ensure the provision of reliable information to establishing continuous interaction with different user groups. In this paper, we postulate that this approach of close collaboration, the so-called twinning of the two NMHSs, was key for the projects’ success and contributed to strengthening the Peruvian NMHS institutionally and procedurally. This project overview guides its reader through the approach, main achievements, and conclusions regarding successes and challenges of the project, and reflects on some potential improvements for future initiative

Twinning SENAMHI and MeteoSwiss to co-develop climate services for the agricultural sector in Peru

The development and dissemination of weather and climate information is crucial to improve people’s resilience and adaptability to climate variability and change. The impacts of climate variability and change are generally stronger for disadvantaged population groups due to their limited adaptive and coping capacities. For instance, smallholder farmers living in remote areas such as the southern Peruvian Andes suffer strongly from adverse weather and climatic events such as droughts or frost. The project Climandes aimed at providing high-quality climate services in support of the agricultural sector in southern Peru by implementing the guidelines of the Global Framework for Climate Services (GFCS). In Climandes, a two-fold challenge was tackled: the co-development of climate services by building up a continuous dialogue between the information provider (in this case the Peruvian national meteorological and hydrological service (NMHS)) and potential users; and the production of climate services through international cooperation. To this end, the NMHSs of Peru (SENAMHI) and Switzerland (MeteoSwiss) worked closely together to tackle issues ranging from the treatment of climate data to ensure the provision of reliable information to establishing continuous interaction with different user groups. In this paper, we postulate that this approach of close collaboration, the so-called twinning of the two NMHSs, was key for the projects’ success and contributed to strengthening the Peruvian NMHS institutionally and procedurally. This project overview guides its reader through the approach, main achievements, and conclusions regarding successes and challenges of the project, and reflects on some potential improvements for future initiatives

Condiciones secas en la zona norte del Perú durante enero, febrero y marzo 2020

El Servicio Nacional de Meteorología e Hidrología del Perú-SENAMHI realiza el monitoreo permanente y elabora las perspectivas en el corto y mediano plazo de las condiciones meteorológicas, hidrológicas y agrometeorológicas para el territorio peruano. Información relevante y oportuna para la toma de decisiones de los diferentes usuarios sectoriales, la misma que es generada a través de sus Direcciones de Línea: Dirección de Meteorología y Evaluación Ambiental Atmosférica, Dirección de Hidrología y Dirección de Agrometeorología. En el presente Informe Técnico se brinda información actualizada sobre el comportamiento meteorológico, hidrológico y agrometeorológico de las cuencas de la región Hidrográfica del Pacífico, sector norte del Perú