Browsing by Author "Rodriguez, Rodolfo"
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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 Restricted Observations of E-region irregularities with ST-Radar in Piura Perú(Instituto Geofísico del Perú, 1993) Woodman Pollitt, Ronald Francisco; Rodriguez, Rodolfo; Balsley, Ben B.During a short period around the first days of february the ST radar located in the campus of the Universidad de Piura, Piura (5°S. 80,5° w), Perú, was pointed in a direction perpendicular to the magnetic field. The goal was to make a quick evaluations of the instrument as a tool to study the E-region at this altitudes. The radar has an antenna of 100m x 100m, with a transmitter with a peak power of 50 kW. A pulse width of 8 usec was used giving a range resolution of 1.2 km. The radar interpulse period was set at 1 msec, given a maximum Nyquist frequency corresponding to a doppler shift of 150 m/sec. The observations lasted several days, but only the last were successful. The first trials were made centered at noon time, influenced by our experience with the E-region echoes at the equator, since this is the time at which the equatorial echoes are the strongest. We obtained no echoes during this trials.Item Open Access On the Abnormally Strong Westward Phase of the Mesospheric Semiannual Oscillation at Low Latitudes During March Equinox 2023(American Geophysical Union, 2024-08-13) Suclupe, Jose; Chau, Jorge L.; Conte, J. Federico; Pedatella, Nicholas M.; Garcia, Rolando; Sato, Kaoru; Zülicke, Christoph; Lima, Lourivaldo M.; Li, Guozhu; Bhaskara Rao, S. Vijaya; Ratnam, M. Venkat; Rodriguez, Rodolfo; Scipión, DannyDifferent meteor radars at low latitudes observed abnormally strong westward mesospheric winds around the March Equinox of 2023, that is, during the first phase of the Mesospheric Semiannual Oscillation. This event was the strongest of at least the last decade (2014–2023). The westward winds reached −80 m/s at 82 km of altitude in late March, and decreased with increasing altitude and latitude. A considerable increase in the diurnal tide amplitude was also observed. The Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension constrained to meteorological reanalysis up to ∼50 km does not capture the observed low-latitude behavior. Additionally, these strong mesospheric winds developed during the westerly phase of the Quasi-Biennial Oscillation, in accordance with the filtering mechanism of gravity waves in the stratosphere proposed in previous works. Finally, analysis of SABER temperatures strongly suggests that the breaking of the migrating diurnal tide may be the main driver of these strong winds.Item Open Access Radar atmosférico para estudios científicos en la Antártida(X Simposium Peruano de Física (Evento), 1993) Rodriguez, Rodolfo; Woodman Pollitt, Ronald FranciscoSe explica una de las causas principales de la destrucción de la capa de ozono y se da a conocer el esfuerzo de un grupo de científicos e ingenieros peruanos por contribuir a estudiar este problema, mediante el diseño y construcción de una radar atmosférico "perfilador de vientos", del tipo ST (Troposfera, Estratosfera) y su instalación y operación en la base peruana Machu Picchu (62°05'29"S, 58°28'16"W) en la Antártida. Este radar, que funciona a efecto doppler, utiliza una técnica nueva desarrollada en el Perú considerada como una de las técnicas más poderosas para el estudio de la atmósfera desde tierra.Item Open Access Short-term prediction of horizontal winds in the mesosphere and lower thermosphere over coastal Peru using a hybrid model(Frontiers Media, 2024-09-23) Mauricio, Christian; Suclupe, Jose; Milla, Marco; López de Castilla, Carlos; Kuyeng, Karim; Scipión, Danny; Rodriguez, RodolfoThe mesosphere and lower thermosphere (MLT) are transitional regions between the lower and upper atmosphere. The MLT dynamics can be investigated using wind measurements conducted with meteor radars. Predicting MLT winds could help forecast ionospheric parameters, which has many implications for global communications and geo-location applications. Several literature sources have developed and compared predictive models for wind speed estimation. However, in recent years, hybrid models have been developed that significantly improve the accuracy of the estimates. These integrate time series decomposition and machine learning techniques to achieve more accurate short-term predictions. This research evaluates a hybrid model that is capable of making a short-term prediction of the horizontal winds between 80 and 95 km altitudes on the coast of Peru at two locations: Lima (12°S, 77°W) and Piura (5°S, 80°W). The model takes a window of 56 data points as input (corresponding to 7 days) and predicts 16 data points as output (corresponding to 2 days). First, the missing data problem was analyzed using the Expectation Maximization algorithm (EM). Then, variational mode decomposition (VMD) separates the components that dominate the winds. Each resulting component is processed separately in a Long short-term memory (LSTM) neural network whose hyperparameters were optimized using the Optuna tool. Then, the final prediction is the sum of the predicted components. The efficiency of the hybrid model is evaluated at different altitudes using the root mean square error (RMSE) and Spearman’s correlation (r). The RMSE ranged from 10.79 to 27.04 ms⁻¹, and the correlation ranged from 0.55 to 0.94. In addition, it is observed that the prediction quality decreases as the prediction time increases. The RMSE at the first step reached 6.04 ms⁻¹ with a correlation of 0.99, while at the sixteenth step, the RMSE increased up to 30.84 ms⁻¹ with a correlation of 0.5.