El proceso del pronóstico del tiempo para el Perú desde la perspectiva del servicio meteorológico

Universidad Nacional Agraria La Molina. Facultad de Ciencias. Departamento Académico de Ingeniería Ambiental, Física y MeteorologíaEsta monografía hace referencia al trabajo realizado como pronosticador en la Subdirección de Predicción Meteorológica (SPM) del Servicio Nacional de Meteorología e Hidrología (SENAMHI). Es durante esta labor que se observó la necesidad de que el SENAMHI como servicios meteorológicos e hidrológicos nacionales (SMHN) provea productos y/o servicios, en el caso de la SPM centrados en el pronóstico del tiempo, de manera eficiente y que estos se mantengan coherentes sin importar que pronosticador los realice, de manera que los usuarios tengan confianza en la información proveída por el servicio. Considerando esta necesidad se decidió redactar protocolos y/o manuales que establecieran las definiciones, procedimientos y herramientas, para las diferentes actividades de la SPM, siendo las principales la elaboración de los diferentes tipos de pronóstico que se realizan de manera regular y la emisión de avisos meteorológicos. Asimismo para poder identificar las etapas, las responsabilidades y usuarios en la elaboración del pronóstico y de avisos meteorológicos, se decidió diagramar los procesos que siguen estos servicios. Es con estos documentos que se espera estandarizar los diferentes pronósticos meteorológicos que se elaboran en la SPM, considerando el tipo de pronóstico, la escala y el objetivo del mismo y, en paralelo, mejorar la eficiencia de los pronosticadores

Behavior of the ITCZ second band near the Peruvian coast during the 2017 coastal El Niño

The behavior of the second band of the Intertropical Convergence Zone (ITCZ) near the Peruvian coast during early 2017 is studied, using precipitation, surface winds, sea surface temperature (SST) and atmospheric variables in different isobaric levels. The proposal of a daily index (Ia) to identify opportunely the formation of this band and the Lorenz energy terms in the region is also considered. This band was present from late January to early April 2017, associated with an anomalous dipole of sea level pressure between the east and west eastern Equatorial Pacific that configured anomalously northerly surface winds and the release of southeasterly trade winds near Peru. In medium levels, a zonally oriented positive mixing ratio anomaly was observed in early March over the ITCZ second band, associated with heavy rain systems over the northern Peruvian coastal region. In the same period, positive anomalies of divergence in high tropospheric levels were observed. The daily Ia index allowed an effective detection of the ITCZ second band 11 days before the maximum coastal precipitation, and the Lorenz energy terms showed eddy kinetic energy (KE) peaks in January and February and a contribution of barotropic instability in equatorial regions.En este estudio se analiza el comportamiento de la segunda banda de la Zona de Convergencia Intertropical (ZCIT) cerca de la costa peruana a inicios de 2017 usando precipitación, vientos superficiales, temperatura superficial del mar y variables atmosféricas en diferentes niveles isobáricos. Además, se propone un índice diario (Ia) para identificar de manera oportuna la formación de esta segunda banda y se considera el análisis de los términos de energía de Lorenz en la región. Esta banda estuvo presente desde los últimos días de enero hasta los primeros días de abril de 2017, asociada con un dipolo anómalo de presión reducida a nivel del mar hacia el este y el oeste del Pacífico Ecuatorial oriental, lo cual configuró vientos superficiales anómalos del norte y relajación de los vientos alisios del sur cerca de la costa peruana. En niveles medios de la troposfera, a inicios de marzo, se observó una anomalía positiva de relación de mezcla proveniente del este sobre la región de la segunda banda de la ZCIT, asociada con sistemas de precipitación intensos sobre la costa norte de Perú. En el mismo periodo se observaron anomalías positivas de divergencia en niveles altos. El índice diario Ia permitió la detección oportuna de la segunda banda de la ZCIT 11 días antes del máximo de precipitación en el norte de la costa peruana, y los términos de energía de Lorenz mostraron picos de energía cinética de las perturbaciones (KE) en enero y febrero, así como contribución de la inestabilidad barotrópica en regiones ecuatoriales

Estudio de condiciones atmosféricas favorables a los incendios forestales en el Perú

El objetivo de este estudio se centró en evaluar las condiciones meteorológicas y circulación atmosférica favorable a la ocurrencia y/o propagación de un IF, usando datos in situ de las estaciones meteorológicas cercanas a las localidades con reporte de IF, reanálisis y modelos meteorológicos. En este contexto, se analizó el comportamiento del índice meteorológico de incendios forestales (FWI, por sus siglas en inglés) en el Perú, un índice utilizado en países tanto de latitudes medias como tropicales, con el fin de aplicarlo para el monitoreo y aviso de condiciones meteorológicas favorables a la propagación de incendios forestales

Reliability of cross-regional applications of global fire danger models: a Peruvian case study

Background: Fire danger indexes (FDIs) are used as proxies for fire potential and are often developed for specific locations. For practical purposes, the extrapolation of the underlying calculations into novel locations is common, but it is generally uncertain if the relationships between FDIs and fire potential observed in the environment in which the index was developed are equally relevant in others. For example, although a topographically, ecologically, and climatologically complex country, f ire danger forecasts in Peru use a standard set of nationwide thresholds applied to the Fire Weather Index. In this study, we validate the underlying assumption that weather-fire relationships are spatially uniform within Peru by (1) making cross-regional comparisons of the statistical distributions of four FDIs—Burning Index, Energy Release Component, Fire Weather Index, and Keetch-Byram Drought Index, and (2) making cross-regional comparisons of the expected daily MODIS hotspot count percentiles conditioned on FDI values. Results: Significant regional differences in the distributions of daily FDI values were observed in every pair of regions within Peru, and with the exception of a pair of regions within the Amazon, little data (< 90 days) were necessary to detect these differences. After controlling for FDI values and seasonal and annual effects with regressions, differences in predicted hotspot percentiles were common, differing by as much as 47 percentage points. Across the pairs of regions, the magnitude of these differences tended to decrease as climatic similarity increased, but some counterexamples were also apparent. Conclusions: The noticeable differences in the distributions of daily FDI values suggest that a standard set of breakpoints may produce unreliable inferences regarding fire potential. We also find that even if the climatic conditions were similar across Peru, the same FDI values in two locations can produce substantially differing predictions of wildfire activity. This suggests that other factors besides FDI values can strongly mediate wildfire activity and that better fire potential predictions could be produced if these factors are accounted for

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Contributions of mean and shape of blood pressure distribution to worldwide trends and variations in raised blood pressure: A pooled analysis of 1018 population-based measurement studies with 88.6 million participants

© The Author(s) 2018. Background: Change in the prevalence of raised blood pressure could be due to both shifts in the entire distribution of blood pressure (representing the combined effects of public health interventions and secular trends) and changes in its high-blood-pressure tail (representing successful clinical interventions to control blood pressure in the hypertensive population). Our aim was to quantify the contributions of these two phenomena to the worldwide trends in the prevalence of raised blood pressure. Methods: We pooled 1018 population-based studies with blood pressure measurements on 88.6 million participants from 1985 to 2016. We first calculated mean systolic blood pressure (SBP), mean diastolic blood pressure (DBP) and prevalence of raised blood pressure by sex and 10-year age group from 20-29 years to 70-79 years in each study, taking into account complex survey design and survey sample weights, where relevant. We used a linear mixed effect model to quantify the association between (probittransformed) prevalence of raised blood pressure and age-group- and sex-specific mean blood pressure. We calculated the contributions of change in mean SBP and DBP, and of change in the prevalence-mean association, to the change in prevalence of raised blood pressure. Results: In 2005-16, at the same level of population mean SBP and DBP, men and women in South Asia and in Central Asia, the Middle East and North Africa would have the highest prevalence of raised blood pressure, and men and women in the highincome Asia Pacific and high-income Western regions would have the lowest. In most region-sex-age groups where the prevalence of raised blood pressure declined, one half or more of the decline was due to the decline in mean blood pressure. Where prevalence of raised blood pressure has increased, the change was entirely driven by increasing mean blood pressure, offset partly by the change in the prevalence-mean association. Conclusions: Change in mean blood pressure is the main driver of the worldwide change in the prevalence of raised blood pressure, but change in the high-blood-pressure tail of the distribution has also contributed to the change in prevalence, especially in older age groups