Ciencias de la Atmósfera e Hidrósfera
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Esta comunidad contiene estudios interdisciplinarios en los campos de la Atmósfera e Hidrósfera (climatología, física atmosférica, hidrología y suelos, oceanografía).
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Item Open Access Posibles registros de lluvias relacionadas a "El Niño" en el desierto de Sechura, noroeste del Perú(1990 Annual Meeting, Medellín, Colombia (Evento), 1990) Machare, José; Ortlieb, Luc; Woodman Pollitt, Ronald Francisco; Guevara, JoséLa ocurrencia de fuertes lluvias es una de las características más llamativas de los fenómenos ENSO en la costa noroeste de Perú. Algunos efectos de estas precipitaciones en el paisaje y la biota pueden permanecer registrados en diferentes tipos de marcadores naturales (características litorales, sedimentos de lagos e inundaciones, y anillos de árboles, entre otros). El desciframiento de este registro geológico y biológico parece ser una forma muy prometedora de reconstruir la historia de este fenómeno oceanográfico y climático global.Item Open Access Algunos apuntes históricos adicionales sobre la cronología de El Niño(Instituto Frances de Estudios Andinos, 1993) Mabres, Antonio; Woodman Pollitt, Ronald Francisco; Zeta, RosaEs necesario continuar haciendo esfuerzos para establecer un registro homogéneo y lo más completo y confiable posible de los eventos del fenómeno ENSO. La región de Piura tiene una alta sensibilidad al fenómeno, cuya presencia da lugar siempre a las abundantes lluvias. Por esto, las fuentes históricas provenientes de esta región son muy importantes. Además complementarán los estudios dendrocronólogicos que se realizan también en la región. Se dan nuevas fuentes históricas sobre las lluvias en Piura. La más interesante es del periódico "El Amigo del Pueblo", del año 1906, que recoge datos a año de 1791 a 1906. Se observa una notable concordancia con la cronología de Eguiguren que recogió Woodman (1985) y que se amplía con dichas fuentes. En cambio, hay algunas discrepancias con la relación de eventos fuertes y medianos que dan Quinn et al. (1987). Se señalan algunos de los intervalos de años (y en años singulares) extremadamente secos en los últimos 200 años.Item Open Access Avances sobre estudios dendrocronológicos en la región costera norte del Perú para obtener un registro pasado del Fenómeno El Niño(Institut Français d'Etudes Andines, 1993) Rodríguez, Rodolfo; Woodman Pollitt, Ronald Francisco; Balsley, Ben; Mabres, Antonio; Phipps, RichardSe presenta un informe de avance sobre un proyecto dendrocronológico en búsqueda de registros de la ocurrencia del fenómeno El Niño en el pasado. El proyecto se desarrolla en la zona norte de la costa del Perú, una región muy sensible a la ocurrencia del fenómeno El Niño y de la Oscilación del Sur (ENSO). Varias especies locales han sido seleccionados para este estudio. éste incluye observaciones fenológicas del crecimiento radial y de las características del anillado de crecimiento en sus ranas y troncos. Las especies más estudiadas y con los registros de observación más largos son el Palo Santo, el Haltaco y el Sapote. Se presentan los registros de crecimiento de estas tres especies, incluyendo años secos y años El Niño. El Sapote no presenta anillos completos de crecimiento. Su crecimiento parece estar controlado principalmente por la presencia de agua en el subsuelo. Sin embargo, éste presenta variaciones, respondiendo a las estaciones y a años lluviosos. El año 1993 ha dejado huellas en su anillado muy conspicuas y sin precedentes. El Hualtaco y el Palo Santo, sí presentan anillos completos. ambos crecen en las zonas montañosas bajas, bien drenadas, que rodean las zonas planas del desierto. Su hábitat cubre varios regímenes de lluvias, de los más secos, donde ellos crecen solamente durante años. El Niño, a los más húmedos, con precipitaciones anuales estacionales, mostrando crecimiento por lo menos durante la estación de lluvias. En los dos casos, ambos muestran respuesta casi inmediata a la carencia o no de lluvias, con crecimiento radial y de nuevas hojas inmediatamente después de la ocurrencia de sólo unos cuantos centímetros de lluvia. Ante la carencia de lluvias y humedad en el suelo, rápidamente pierden sus hojas, pudiendo dormitar por años en este estado, en las zonas más secas. Un análisis preliminar de las correspondencia entre la intensidad de las precipitaciones en las zonas más lluviosas y el espesor del anillado en el Palo Santo permite ver una alta correlación entre ambas, mostrando a la vez el potencial de esta especie para establecer una cronología de la intensidad de las lluvias en el pasado, y por ende de la ocurrencia del fenómeno El Niño.Item Open Access Análisis del pronóstico del Fenómeno de El Niño evacuado por NCEP/NOAA el 03 de diciembre de 1997: impacto sobre las lluvias en la costa norte del país(Instituto Geofísico del Perú, 1997-12-08) Woodman Pollitt, Ronald FranciscoA comienzos de Diciembre de los corrientes la National Prediction Environmental Center de la NOAA (NCEP/NOAA http://nic.fb4.noaa.gov/research/climate.html) evacuó los resultados de su última corrida ( 3 de Dic. ) de su modelo acoplado océano-atmósfera (CMP12), con los pronósticos de la temperatura del mar del Pacífico Ecuatorial para los próximos 12 meses. Los valores de la temperatura mas cercanas a las costas de Paita y Chicama evaluadas por el modelo han sido usados para pronosticar la intensidad de las futuras precipitaciones, específicamente en la ciudad de Piura. Las lluvias en la ciudad de Piura se pueden usar como índice de las lluvias en la costa-norte del país, pero con las debidas consideraciones a las gradientes tan pronunciadas en la temperatura del mar -y las correspondientes precipitaciones -, al acercarse a las regiones fronterizas con el Ecuador y las zonas montañosas. Se ha usado Piura por su largo registro metereológico, el cual permite hacer comparaciones con años pasados.Item Open Access Dendrochronological laboratory for studies relate to ENSO events in the tropical zone of South-America(Instituto Geofísico del Perú, 1999) Rodriguez, Rodolfo; Mabres, Antonio; Flores, Luis; Woodman Pollitt, Ronald Francisco; Luckman, Brian H.The Collaborative Research Network (CRN) project the assessment of present, past and future climate variability in the Americas from freeline environments, currently under development by institutions of Argentina, Bolivia, Canada, Chile and United State. The goal of this CRN project is the recovery of tree-ring records of past climate from freelines sits along the cordillera between Alaska and Tierra del Fuego. It will be used to reconstruct the major made of interhemispheric climate variability for the past centuries free-ring reconstruction of precipitation and temperature will allow delailed study of local and regional climate variability, how it changes with latitude and is linked to the major elements of ocean and global circulation, through a proposal to the program to expand capacity in the Americas (PESCA) of inter-American Institute for Global change Research (IAI) a very and critical area of South-America has been incorporate to such as studies.Item Open Access Dendrochronological studies in the Peruvian north coast relate to ENSO(Instituto Geofísico del Perú, 2000) Rodríguez, R.; Mabres, A.; Flores, L.A.; Woodman Pollitt, Ronald FranciscoDendrochronological studies in the peruvian nort coast to find records of past El Niño - Southern Oscillation (ENSO) events began an the ale 80's. The peruvian north coast is the west-most area of South America, close to equator (05o S 80o W) and to the Sechura desert, is a very sensitive area to the climatic changes due to ENSO. An initial selection of several regional trees have been done for study. The study includes phenological observations and tree ring characteristics analysis as well as racial growth control of tree trunks and branches. The species more intensively studied and suitable to fina records due to the ENSO are Palo Santo, Hualtaco and Sapote.Item Open Access Introduction to El Niño phenomena: a Peruvian perspective(ISEA-10, 2000-02) Woodman Pollitt, Ronald FranciscoThe recent interest in El Niño Phenomenon stems from: 1) our better understanding of the physical processes involved, which in turn has made possible its early prediction, 2) the realization that it affects the climate at a global scale, and 3) its unusual recent intense episodes and their higher frequency of occurrence. The behavior of EI Niño during the 1997-98 cycle was successfully predicted with six or more months in advance. From an equatorial eastern-Pacific point of view, more specifically from the long tradition and historical records available in Piura, Peru (-5ºS, 79°W), the 1997-98 and the 1982-83 El Niño have been the strongest recorded in the last 470 years, i.e., since the Spanish foundation of the city. Piura is the oldest post-Hispanic city in the whole South American continent and the most sensitive to El Niño related climatic variations. While the phenomena have only recently caught the attention of the world, its existence was well known by the local population. In fact, the name, El Niño (Christ Child), was coined by the fishermen of the area, with the believe that the warm waters associated with the phenomena carne with the northern current which appeared around Christmas time. The author was born and brought up in Piura. This may explain why an upper-atmospheric physicist has been invited to give a talk on the subject. Climatologists have come to realize that, after the well-known seasonal variations, the most important "predictable" climatic variations are the inter-annual ones related to El Niño. Its statistical signature can be observed far beyond the coastal areas around the equatorial Pacific and includes the effects on the climate of the Australian and whole American continent, the Asían monsoons and the frequency and intensity of hurricanes in the Caribbean, to mention a few.Item Open Access The atmospheric circulation associated with extreme rainfall events in Piura, Peru, during the 1997-1998 and 2002 El Niño events(European Geosciences Union (EGU), 2004-11-29) Takahashi, KenThe lowland of Piura, in northwestern Peru, is very strongly impacted by El Niño. Its climate is arid but can experience very heavy rainfall associated with the high nearby sea surface temperature (SST) during El Niño events. Rainfall, however, tends to occur in discrete, intense events and an understanding of the physical conditions favoring a particular day with heavy rainfall over others is of both scientific and practical interest. In this work, we consider the rainy periods of December 1997 to April 1998 and March to April 2002, corresponding to very strong and weak to moderate El Niño conditions, respectively, and search for systematic differences in the atmospheric circulation that may account for the day-to-day variability of rainfall in Piura. Composites of vertical profiles of winds measured by wind profiling radars in Piura, as well as composites of NCEP/NCAR Reanalysis wind fields, suggest that rainy days are associated with an enhanced onshore westerly low-level flow, which may help the triggering of convection by orographic lifting over the western slope of the Andes. Synoptic control was evident in the rainfall record for 1997-1998 but was not as clear in that of 2002. However, in both periods of study the low-level flow over Piura, which we found to be important for the triggering of rainfall, was modulated by tropical synoptic scale disturbances. The structures of the composited wind differences suggest that they may be related to equatorially trapped tropospheric waves, particularly Kelvin and n=1 Rossby waves.Item Restricted Sensitivity studies of the RegCM3 simulation of summer precipitation, temperature and local wind field in the Caribbean Region(Springer, 2006) Martínez Castro, Daniel; Porfirio da Rocha, R.; Bezanilla-Morlot, A.; Alvarez-Escudero, L.; Reyes-Fernández, J. P.; Silva Vidal, Yamina; Arritt, R. W.We present a preliminary evaluation of the performance of three different cumulus parameterization schemes in the ICTP Regional Climate Model RegCM3 for two overlapping domains (termed ‘‘big’’ and ‘‘small’’) and horizontal resolutions (50 and 25 km) in the Caribbean area during the summer (July–August–September). The cumulus parameterizations were the Grell scheme with two closure assumptions (Arakawa–Schubert and Fritsch–Chappell) and the Anthes-Kuo scheme. An additional sensitivity test was performed by comparing two different flux parameterization schemes over the ocean (Zeng and BATS). There is a systematic underestimation of air temperature and precipitation when compared with analyzed data over the big domain area. Greater ( 2 ºC) and smaller ( 0.9 ºC) negative temperature biases are obtained in Grell–FC and Kuo convective scheme, respectively, and intermediate values are obtained in Grell–AS. The small domain simulation produces results substantially different, both for air temperature and precipitation. Temperature estimations are better for the small domain, while the precipitation estimations are better for the big domain. An additional experiment showed that by using BATS to calculate the ocean fluxes in the big domain instead of the Zeng scheme, precipitation increases by 25% and the share of convective precipitation rose from 18% to 45% of the total, which implies a better simulation of precipitation. These changes were attributed to an increase of near surface latent heating when using BATS over the ocean. The use of BATS also reduces the cold bias by about 0.3–0.4 ºC, associated with an increase of minimum temperature. The behavior of the precipitation diurnal cycle and its relation with sea breeze was investigated in the small domain experiments. Results showed that the Grell–Arakawa–Schubert closure describes better this circulation as compared with Grell–Fritsch–Chappell closure.Item Open Access Variability and climate change in the Mantaro river basin, central Peruvian Andes(INPE, 2006-04) Silva Vidal, Yamina; Takahashi, Ken; Cruz, Nicolas; Trasmonte Soto, Grace Liliam; Mosquera Vásquez, Kobi Alberto; Nickl, Elsa; Chávez, Raúl; Segura Curi, Berlín Aveles; Lagos Enríquez, PabloThe present work is part of the "Integrated Local Assessment of the Mantaro River Basin" (ILA Mantaro), whose main objective was: to systematize and to extend the knowledge about climate change in the Mantaro river basin, and to evaluate the climatic, physical and social aspects of its vulnerability, as well as to identify viable adaptation options for the agriculture, hydroelectric energy and health sectors, to be incorporated into local and regional development planning. In this context, the climatic component of the study consisted in the analysis of the climatic characteristics of the river basin: intraseasonal and interannual variability of rainfall over the basin, the relation of regional climate with atmospheric patterns on regional and global scale, the climatic trends in the last 50 or 40 years, and the characteristics of the freezes and the trends in their frequency and intensity. On the other hand, the generation of future climatic scenarios for the river basin, constituted one of the most important objectives. These results were used for the analysis of the present and future vulnerability in the Mantaro river basin to climate variability and change, as well as for the proposal of adaptation measures.Item Open Access Trends in maximum and minimum temperature in the Central Andes of Peru (Mantaro River Basin)(INPE, 2006-04) Trasmonte Soto, Grace Liliam; Silva Vidal, Yamina; Chávez, Raúl; Segura Curi, Berlín AvelesThe Mantaro River Basin (34550,08 Km2) is located on the eastern slope of the central Peruvian Andes, between the coordinates 10º34’30’’S- 13º35’30’’S/ 73º55’00’’W- 76º40’30”W. This is a very complex basin due to its geomorphology, with almost 85% of its territory located above 3000 masl. This basin was chosen for an Integrated Local Assessment with a Climate Change perspective, because its strategic location. The Mantaro basin provides a constant supply of resources (water, energy and farming products) to Lima, the capital of Peru. This is the first effort made until now in this respect in our country. In this context, a linear trend analysis of observed temperature data (minimum and maximum) has been performed, using monthly and daily data for the1960-2002 period, provided by nine meteorological stations, with altitudes ranging from 3150 masl to 4413 masl.Item Open Access Peru’s approach to climate change in the andean mountain region: achieving multidisciplinary regional cooperation for integrated assessment of climate change(International Mountain Society (IMS), 2007-02) Lagos Enríquez, PabloClimate change aggravates the challenges of sustainable development in mountain regions and calls for deeper insights into impacts on the vulnerability of mountain people and their options for adapting to changing conditions. Peru is considered highly vulnerable to climate change. Therefore, its government has initiated a program to strengthen the capacity for transdisciplinary research in order to propose adaptation measures and reduce the negative impacts of climate change. The present article describes the strategy for selecting the study area and for achieving collaboration between natural and social scientists, stakeholders, decision-makers, and other societal groups, in order to carry out an integrated assessment of climate change in the mountainous ecosystems region of central Peru, with an emphasis on vulnerability and adaptation.Item Restricted Processes controlling the mean tropical Pacific precipitation pattern. Part II: The SPCZ and the southeast Pacific dry zone(American Meteorological Society, 2007-12-01) Takahashi, Ken; Battisti, David S.The nature of the South Pacific convergence zone (SPCZ) is addressed by focusing on the dry (and cool) zone bounded by it and the coast of South America through numerical experiments. As shown in a companion paper, this dry zone is due, to a large extent, to orographically forced subsidence. Here it is shown that the northwestward expansion of this dry zone can be explained by advection of low moist static energy by the trade winds. These results provide an explanation of the geometry of the western edge of the dry zone and, therefore, of the eastern edge of the adjacent SPCZ. Sea surface temperature underneath the SPCZ is enhanced by relatively high near-surface humidity through evaporative processes, which feeds back into its organization. However, in this model, this feedback is not critical for the existence of the SPCZ. The subsidence associated with the ITCZ in the North Hemisphere negatively affects the precipitation rate in the SPCZ. It was also found that the sensitivity of the forced response is largest for peak orographic heights below 3000 m, which indicates that the exact representation of the Andes in numerical models might not be as critical as that of lower orography such as that in southern Africa.Item Open Access Numerical study of the response of the ocean to a northerly wind jet in the equatorial Eastern Pacific(Advanecs in Geosciences, 2008-04-10) Mosquera Vásquez, Kobi AlbertoThe response of the equatorial and South American coastal ocean circulation to the anomalous March 2002 wind jet extending from the Gulf of Panama to 6° S is studied in a linear ocean model. Two experiments were performed: one without continental boundaries and the other with an eastern boundary at 81° W, representing the American continent. The spatial and temporal structure of the imposed wind anomaly, represented with idealized mathematical functions, is similar to that of the real jet. The duration of the wind jet was six days where the maximum intensity occurred at the third day. The results of the experiments indicate that the wind-jet anomaly over the Gulf of Panama is another source of ocean waves that influence the western coast of South America in the form of coastal Kelvin waves (CKW).Item Open Access Frost risks in the Mantaro river basin(European Geosciences Union (EGU), 2008-04-10) Trasmonte Soto, Grace Liliam; Chávez, Raúl; Segura Curi, Berlín Aveles; Rosales, J. L.As part of the study on the Mantaro river basin’s (central Andes of Peru) current vulnerability to climate change, the temporal and spatial characteristics of frosts were analysed. These characteristics included intensity, frequency, duration, frost-free periods, area distribution and historical trends. Maps of frost risk were determined for the entire river basin, by means of mathematical algorithms and GIS (Geographic Information Systems) tools, using minimum temperature – 1960 to 2002 period, geomorphology, slope, landuse, types of soils, vegetation and life zones, emphasizing the rainy season (September to April), when the impacts of frost on agriculture are most severe. We recognized four categories of frost risks: low, moderate, high and critical. The critical risks (with a very high probability of occurrence) were related to high altitudes on the basin (altitudes higher than 3800 m a.s.l.), while the low (or null) probability of occurring risks were found in the lower zones (less than 2500 m a.s.l.). Because of the very intense agricultural activity and the high sensitivity of the main crops (Maize, potato, artichoke) in the Mantaro valley (altitudes between 3100 and 3300 m a.s.l.), moderate to high frost risks can be expected, with a low to moderate probability of occurrence. Another significant result was a positive trend of 8 days per decade in the number of frost days during the rainy season.Item Open Access Dry and wet rainy seasons in the Mantaro river basin (Central Peruvian Andes)(European Geosciences Union, 2008-04-10) Silva Vidal, Yamina; Takahashi, Ken; Chávez, RaúlMonthly precipitation data from the period of 1970 to 2004 from 38 meteorological stations in the Mantaro river basin were used to classify the rainy seasons (September–April) of each year into anomalously dry or wet, and to determine the basin-wide extent of the anomalies based on the Standardized Precipitation Index (SPI). The wet periods mostly occurred in the early 1970's and during the first half of the 1980's, except for the event that occurred in the 1993/94 period which was the strongest and most generalized in the analyzed period. The dry periods occurred mostly during the second half of the 1980's and the 1990's. Consistent with this, a negative trend in precipitation of 2% per decade was found for the rainy season, due mainly to a stronger trend (−4%/decade) during the peak phase (January–March). Despite previously reported significant negative correlations between El Niño-Southern Oscillation (ENSO) and rainfall during the peak of the rainfall season, the similar amplitude variability of precipitation during the onset phase of the rainfall season (September–December), which is uncorrelated with ENSO, participate to the reduction of the absolute correlation for the full rainfall season. Correlations between rainfall in the Mantaro basin and sea surface temperature (SST) in the tropical Atlantic are significant only near the end of the rainy season, with more rain associated with a weaker north-south difference in SST in the tropical Atlantic.Item Open Access El Niño – related precipitation variability in Perú(European Geosciences Union (EGU), 2008-04-10) Lagos Enríquez, Pablo; Silva Vidal, Yamina; Nickl, E.; Mosquera Vásquez, Kobi AlbertoThe relationship between monthly mean sea surface temperature (SST) anomalies in the commonly used El Niño regions and precipitation for 44 stations in Perú is documented for 1950–2002. Linear lag correlation analysis is employed to establish the potential for statistical precipitation forecasts from SSTs. Useful monthly mean precipitation anomaly forecasts are possible for several locations and calendar months if SST anomalies in El Niño 1+2, Niño 3.4, and Niño 4 regions are available. Prediction of SST anomalies in El Niño regions is routinely available from Climate Prediction Center, NOAA, with reasonable skill in the El Niño 3.4 region, but the prediction in El Niño 1+2 region is less reliable. The feasibility of using predicted SST anomalies in the El Niño 3.4 region to predict SST anomalies in El Niño 1+2 region is discussed.Item Restricted Spatio‐temporal rainfall variability in the Amazon basin countries (Brazil, Peru, Bolivia, Colombia, and Ecuador)(Royal Meteorological Society, 2008-09) Espinoza, Jhan Carlo; Ronchail, Josyane; Guyot, Jean Loup; Cochonneau, Gerard; Naziano, Filizola; Lavado, Waldo; De Oliveira, Eurides; Pombosa, Rodrigo; Vauchel, PhilippeRainfall variability in the Amazon basin (AB) is analysed for the 1964–2003 period. It is based on 756 pluviometric stations distributed throughout the AB countries. For the first time it includes data from Bolivia, Peru, Ecuador, and Colombia. In particular, the recent availability of rainfall data from the Andean countries makes it possible to complete previous studies. The impact of mountain ranges on rainfall is pointed out. The highest rainfall in the AB is observed in low windward regions, and low rainfall is measured in leeward and elevated stations. Additionally, rainfall regimes are more diversified in the Andean regions than in the lowlands. Rainfall spatio‐temporal variability is studied based on a varimax‐rotated principal component analysis (PCA). Long‐term variability with a decreasing rainfall since the 1980s prevails in June–July–August (JJA) and September October–November (SON). During the rainiest seasons, i.e. December–January–February (DJF) and March–April–May (MAM), the main variability is at decadal and interannual time scales. Interdecadal variability is related to long‐term changes in the Pacific Ocean, whereas decadal variability, opposing the northwest and the south of the AB, is associated with changes in the strength of the low‐level jet (LLJ) along the Andes. Interannual variability characterizes more specifically the northeast of the basin and the southern tropical Andes. It is related to El Niño‐Southern Oscillation (ENSO) and to the sea surface temperature (SST) gradient over the tropical Atlantic. Mean rainfall in the basin decreases during the 1975–2003 period at an annual rate estimated to be − 0.32%. Break tests show that this decrease has been particularly important since 1982. Further insights into this phenomenon will permit to identify the impact of climate on the hydrology of the AB. Copyright © 2008 Royal Meteorological Society.Item Open Access Propuesta de gestión de riesgo de heladas, que afectan a la agricultura del Valle del Mantaro (Andes Centrales del Perú)(Universidad Ricardo Palma, 2009) Trasmonte Soto, Grace Liliam; Montoya Terreros, Haydée; Avilés Merens, Diana; Lavell, AllanSe ha desarrollado una propuesta de gestión de riesgo de helada (GRH), para un valle interandino y eminentemente agrícola: el valle del Río Mantaro (VM), ubicado en los Andes centrales del Perú. La elaboración de la propuesta conllevó a un proceso participativo, con intervención y aporte significativo de los principales actores de la actividad agrícola de la zona: agricultores, comuneros, técnicos de las principales instituciones gubernamentales relacionadas a la agricultura y defensa civil, autoridades regionales y/o locales o sus representantes, instituciones de investigación meteorológica y agrícola, entre otros. Se considero cuatro etapas principales en la ejecución de la investigación: Estudio general de la zona de estudio, la evaluación del peligro de heladas, el análisis de la vulnerabilidad/debilidades y capacidades/fortalezas en la GRH del calle y por último la elaboración de la propuesta de gestión. En el estudio general se analizó los principales aspectos físico-geográficos del valle y lo relacionado a la actividad agrícola que se desarrolla. En la evaluación del peligro, se analizó en forma detallada las características de las heladas en la zona, básicamente de tipo agronómico (temperaturas mínimas del aire, que afectan a los cultivos principales del valle), los cuales ocurren en el período de mayor desarrollo y producción agrícola en la región: entre setiembre y abril. Se identificó las propiedades más importantes que intervienen en su "peligrosidad, las cuales aminoran o amplifican su impacto en la agricultura (intnsidad, duración, origen, mes de ocurrencia, probabilidad de ocurrencia, distribución espacial, relación con otros eventos meteorológicos adversos, relación con el fenómeno El Niño/La Niña y relación con el cambio climático), dichas propiedades fueron utilizadas para la definición de un "Indíce Integrado de Heladas". Además, se confeccionaron mapas de peligro de heladas a escala local (nivel de distrito), elaborados utilizando la técnica de mapeo participativo, por los mismos agricultores y comuneros de dos zonas del valle: Concepción (ubicado en la provincia de Concepción) y Quilcas (perteneciente a la provincia de Huancayo), representativas de dos manejos diferentes de agricultura en la zona: por riesgo y por secano respectivamente. Se evalúo el impacto físico a los principales cultivos (especialmente papa y choclo) y socio-económico a los agricultores del valle, debido a las heladas, documentando el último evento más fuerte ocurrido en los últimos años, del 17 de febrero de 2007. De todo este proceso, la propuesta final se obtuvo evaluando e integrando los conocimientos físico-atmosféricos de las heladas que afectan a la agricultura de la zona, el actual conocimiento y acción de instituciones gubernamentales de la zona encargadas de la gestión de riesgo en el valle, junto con el conocimiento y acción local (actual y ancestral) que realizan los agricultores del valle, identificando los principales problemas y dando posibles soluciones.Item Open Access Comparación de los métodos regresión multivariada adaptativa utilizando splines (MARS) y redes neuronales artificiales backpropagation (RNAB) para el pronóstico de lluvias y temperaturas en la Cuenca del río Mantaro(Universidad Nacional Agraria La Molina, 2009) Latínez Sotomayor, Karen Alexandra; Menacho, César; Chávez, RaúlMuchas actividades agrícolas dependen significativamente de la precipitación y la temperatura, afectando la producción y productividad de los cultivos. La cuenca del río Mantaro, (Junín-Perú), está expuesta a una alta variabilidad climática debido a su ubicación y características geográficas. Además, son escasos los trabajos de investigación sobre la elaboración y utilización de pronósticos climáticos para aprovecharlos en la agricultura, por ello esta investigación se plantea ampliar el conocimeinto al respecto. Se utilizaron datos de las estaciones de Huayao, Santa Ana, Jaula y Viques, y una vez que estos datos fueron revisados y se eliminaron los valores atípicos extremos se procedió a su análisis con las técnicas: Regresión Multivariada Adaptativa utilizando Splines (MARS) y las Redes Neuronales Artificiales Backpropagation (RNAB). Las redes neuronales utilizada para el análisis consta de 17 nodos en el caso de las precipitaciones y 15 para las temperaturas tanto mínimas como máximas. Las variables explicativas que se utilizaron en este estudio son variables globales provenientes de información secundaria, siendo recomendable que para próximos estudios se revise la calidad de esas variables. Los inputs utilizados tienen un desfase de tres meses (lag=3). Los resultados mostraron que los pronósticos obtenidos al utilizar el modelo MARS tienen menor error que los obtenidos con las RNAB, a excepción de la variable Temperatura Máxima de Huayao en donde la RNAB resultó con menos errores que el modelo MARS.