Estudio de la frecuencia de nevadas en el Perú

Las nevadas son un componente crítico del sistema hidrológico en las regiones de altitud media y alta incluso en paisajes montañosos. Las nevadas también juegan un papel importante en el intercambio de energía y agua entre la atmósfera y la tierra. La presencia de nieve aumenta el albedo superficial, lo que resulta en un enfriamiento regional sobre las regiones cubiertas de nieve. La nieve es también una importante reserva de agua y actúa como amortiguador en el sistema hidrológico que controla la descarga de los ríos y los procesos y peligros ambientales asociados. En el Perú, sin embargo, también causan grandes pérdidas económicas en la sierra, estas pueden generar efectos adversos en el sector agrícola, turismo, transporte y vivienda, e incluso, daños en la salud, especialmente en los sectores central y sur del país. Estas precipitaciones suelen presentarse en localidades por encima de los 3800 msnm. A pesar de presentar un riesgo para el país, las nevadas tienen escasas mediciones y carecen de un registro histórico extenso

Un buen clima : glosario de términos meteorológicos

En este folleto encontrarás términos que habrás escuchado más de una vez pero que, no siempre se usan adecuadamente. Por ello, con el fin de comprender los principales conceptos que utiliza el Servicio Nacional de Meteorología e Hidrología del Perú (SENAMHI), se ha elaborado este glosario para todas las personas que colaboran con nuestra institución, en la correcta difusión de la información meteorológica

Dry season circulation-type classification applied to precipitation and temperature in the Peruvian Andes

We present the first systematic classification of circulation regimes that characterize the Tropical Andes during the dry season (May–August). We apply the hierarchical k-means clustering method to ERA-Interim reanalysis data of daily mean geopotential height at 500- and 200-hPa levels for the period 1981–2015. Specifically, by combining the variability in intensity and location of geopotential anomalies we identify 12 circulation types (CTs). We then establish the relationship between the CTs and surface conditions in the Peruvian Andes (PA) analysing high-resolution gridded datasets of daily mean temperature and rainfall. Our results indicate that intense precipitations and low minimum temperatures are often associated with an Upper Tropospheric Trough (UTT) centred at subtropical latitudes (~30°S) and between 80° and 70°W of longitude. Moreover, drier and warmer conditions across the entire PA region are largely associated with three anticyclonic CTs. Strong negative anomalies in daily maximum (minimum) temperatures can be related to the effect of day (night) cloudiness in the radiative balance, but also to subtropical cold air advections favoured by the UTT. While CTs featuring warmer (colder) conditions have become more (less) frequent in the last decades of the record, there is no systematic link between positive or negative trends in occurrence and the wetter and drier character of the CTs. The annual frequencies of 10 CTs are significantly correlated with El Niño-Southern Oscillation, with warmer and drier (cooler and wetter) CTs generally preceded by an El Niño (La Niña) in the previous wet season

Current thermal state of permafrost in the southern Peruvian Andes and potential impact from El Niño–Southern Oscillation (ENSO)

Tropical high‐mountain permafrost has a unique thermal regime due to its exposure to strong solar radiation and to rough surface snow morphology, which reduce ground heat transfer from the surface. Latent heat transfer and higher albedo that occur during the snow‐covered season contribute to positive feedback that supports the presence of permafrost. This preliminary study reports on the thermal state characteristics of tropical mountain permafrost in Peru. This work also evaluates the potential combined impact of the El Niño–Southern Oscillation (ENSO) in the mountain permafrost of the Coropuna and Chachani volcanic complexes, both located at the western edge of the southern Peruvian Altiplano. Temperature monitoring boreholes were established at 5,217 m at Coropuna and 5,331 m at Chachani, and electrical resistivity was surveyed in both sites. This 7‐year discontinuous record of permafrost temperature data encompasses historically extreme El Niño/La Niña events. Our results show that the current lower‐altitude permafrost boundary (~5,100 m a.s.l.) is critically influenced by the balance of wet and dry seasons: permafrost tends to deplete during drought years. Typical permafrost thickness was 10–20 m and contained ice‐rich pore spaces. The presence of permafrost and its thermal resistance depends on ice content and on higher albedo, usually due to: (a) hydrothermal alteration, which transforms the volcanic rocks into surfaces with ideal albedo for permafrost resilience; and (b) sublimation of the snow cover, forming ice‐pinnacles named penitentes

Characteristics of Precipitating Storms in Glacierized Tropical Andean Cordilleras of Peru and Bolivia

Precipitation variability in tropical high mountains is a fundamental yet poorly understood factor influencing local climatic expression and a variety of environmental processes, including glacier behavior and water resources. Precipitation type, diurnality, frequency, and amount influence hydrological runoff, surface albedo, and soil moisture, whereas cloud cover associated with precipitation events reduces solar irradiance at the surface. Considerable uncertainty remains in the multiscale atmospheric processes influencing precipitation patterns and their associated regional variability in the tropical Andes—particularly related to precipitation phase, timing, and vertical structure. Using data from a variety of sources—including new citizen science precipitation stations; new high-elevation comprehensive precipitation monitoring stations at Chacaltaya, Bolivia, and the Quelccaya Ice Cap, Peru; and a vertically pointing Micro Rain Radar—this article synthesizes findings from interdisciplinary research activities in the Cordillera Real of Bolivia and the Cordillera Vilcanota of Peru related to the following two research questions: (1) How do the temporal patterns, moisture source regions, and El Niño-Southern Oscillation relationships with precipitation occurrence vary? (2) What is the vertical structure (e.g., reflectivity, Doppler velocity, melting layer heights) of tropical Andean precipitation and how does it evolve temporally? Results indicate that much of the heavy precipitation occurs at night, is stratiform rather than convective in structure, and is associated with Amazonian moisture influx from the north and northwest. Improving scientific understanding of tropical Andean precipitation is of considerable importance to assessing climate variability and change, glacier behavior, hydrology, agriculture, ecosystems, and paleoclimatic reconstructions