Browsing by Author "Milla, Marco"
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Item Restricted A multi-beam incoherent scatter radar technique for the estimation of ionospheric electron density and Te/Ti profiles at Jicamarca(Elsevier, 2013-12) Milla, Marco; Kudeki, Erhan; Reyes, Pablo M.; Chau Chong Shing, Jorge LuisA multi-beam incoherent scatter radar technique has been developed at the Jicamarca Radio Observatory in order to maximize the number of ionospheric parameters that can be estimated simultaneously. The technique interleaves radar observations with antenna beams pointing perpendicular and oblique to the Earth's magnetic field. For the estimation of the ionospheric parameters, we have modeled the magnetic aspect angle variations of the signal power and cross-correlation data measured in multiple directions. The data model, formulated in terms of soft-target radar equations, was built based on the theories of incoherent scattering and magneto-ionic propagation. Applying a nonlinear least-squares inversion algorithm, we have succeeded in measuring simultaneously ionospheric electron densities Ne, electronto-ion temperature ratios Te=Ti as well as vertical and zonal plasma drifts. In the past, radar users had to choose between either perpendicular-to-B or oblique modes, thus, the application of this technique extends the current capabilities of the Jicamarca radar.Item Restricted A multistatic HF beacon network for ionospheric specification in the Peruvian sector(American Geophysical Union, 2016-05-04) Hysell, D. L.; Milla, Marco; Vierinen, J.A small network of HF beacon transmitters and receivers has been deployed in Peru for specifying the F region ionosphere in the sector. The effort is motivated by ionospheric disturbances associated with equatorial spread F (ESF) and specifically disturbances arising under inauspicious conditions for ESF as determined by numerical simulations. The beacons operate at dual frequencies (2.72 and 3.64 MHz). They are CW but incorporate pseudorandom noise (PRN) coding so that the group delays of the links can be measured. Other observables are power, Doppler shift, bearing, and polarization. A transmitter is currently deployed at Ancon (11∘46’37’’S, 77∘09’1’’W, 51 m above sea level (asl)), while receivers are at Jicamarca (11∘57’5.8’’S, 76∘52’27’’W, 510 m asl) and Huancayo (12∘02’30’’S, 75∘19’15’’W, 3315 m asl). An algorithm for inverting the beacon data combined with electron density profiles from Jicamarca is described. Data and representative solutions from an experimental campaign held in August 2015 are presented and evaluated.Item Restricted A study on meteor head echo using a probabilistic detection model at Jicamarca(American Geophysical Union, 2020-01) Li, Yanlin; Zhou, Qihou; Scott, Mark; Milla, MarcoA coded long pulse is applied to the Jicamarca 50 MHz high power large aperture radar to study meteor head echoes. We develop a probabilistic detection model, which finds 25% more meteors than the commonly used signal‐to‐noise threshold method. The long code and the probabilistic approach allow us to detect over 180 meteors per minute during the dawn hours, which is several times higher than reported previously. The typical mass of the meteoroids is estimated to be about 10−9 kg, slightly smaller than other sensitive very‐high‐frequency and ultrahigh‐frequency high power large aperture radars except the Arecibo radar. The high sensitivity allows us to observe numerous meteors in the presence of the strongest equatorial electrojet. We report and discuss the characteristics of meteor flux rate, ablation height, and velocity with a constant noise power for the first time for the Jicamarca radar. The highest average detection height is found to be near 2 a.m., instead of near 6 a.m. when the largest average velocity is observed. This is likely due to the combination of the relative large atmospheric velocity and the substantial atmospheric entry angles around 2 a.m. The observed characteristics suggest that many meteors are detected 8° off zenith despite that the full beam width is only 2.4°.Item Open Access Ajuste de espectros usando MPI(Instituto Geofísico del Perú, 2010) Zamudio, A.; Milla, MarcoContenido de la charla: 1. Planteamiento del Problema -Modos de Dispersion Incoherente 2. Non Linear Least-Square -Algoritmo de Levenberg-Marquardt 3. JRO Cluster -Software - Hardware 4. Implementacion del Algoritmo - Método de Trabajo 5. Resultados.Item Open Access AMISR-14: Observations of equatorial spread F(American Geophysical Union, 2015-06-11) Rodrigues, F. S.; Nicolls, M. J.; Milla, Marco; Smith, J. M.; Varney, R. H.; Strømme, A.; Martinis, C.; Arratia, J. F.A new, 14-panel Advanced Modular Incoherent Scatter Radar (AMISR-14) system was recently deployed at the Jicamarca Radio Observatory. We present results of the first coherent backscatter radar observations of equatorial spread F (ESF) irregularities made with the system. Colocation with the 50 MHz Jicamarca Unattended Long-term studies of the Ionosphere and Atmosphere (JULIA) radar allowed unique simultaneous observations of meter and submeter irregularities. Observations from both systems produced similar Range-Time-Intensity maps during bottom-type and bottomside ESF events. We were also able to use the electronic beam steering capability of AMISR-14 to “image” scattering structures in the magnetic equatorial plane and track their appearance, evolution, and decay with a much larger field of view than previously possible at Jicamarca. The results suggest zonal variations in the instability conditions leading to irregularities and demonstrate the dynamic behavior of F region scattering structures as they evolve and drift across the radar beams.Item Open Access Analysis of extreme meteorological events in the central Andes of Peru using a set of specialized instruments(MDPI, 2021-03-21) Flores Rojas, José Luis; Silva Vidal, Yamina; Suárez Salas, Luis; Estevan, René; Valdivia Prado, Jairo Michael; Saavedra Huanca, Miguel; Giráldez, Lucy; Piñas-Laura, Manuel; Scipión, Danny; Milla, Marco; Kumar, Shailendra; Martínez Castro, DanielA set of instruments to measure several physical, microphysical, and radiative properties of the atmosphere and clouds are essential to identify, understand and, subsequently, forecast and prevent the effects of extreme meteorological events, such as severe rainfall, hailstorms, frost events and high pollution events, that can occur with some regularity in the central Andes of Peru. However, like many other Latin American countries, Peru lacks an adequate network of meteorological stations to identify and analyze extreme meteorological events. To partially remedy this deficiency, the Geophysical Institute of Peru has installed a set of specialized sensors (LAMAR) on the Huancayo observatory (12.04º S, 75.32º W, 3350 m ASL), located in the Mantaro river basin, which is a part of the central Andes of Peru, especially in agricultural areas. LAMAR consists of a set of sensors that are used to measure the main atmosphere and soil variables located in a 30-meter-high tower. It also has a set of high-quality radiation sensors (BSRN station) that helps measure the components of short-wave (SW) (global, diffuse, direct and reflected) and long-wave (LW) (emitted and incident) irradiance mounted in a 6-meter-high tower. Moreover, to analyze the microphysics properties of clouds and rainfall, LAMAR includes a set of profiler radars: A Ka-band cloud profiler (MIRA-35c), a UHF wind profiler (CLAIRE), and a VHF wind profiler (BLTR), along with two disdrometers (PARSIVEL2) and two rain gauges pluviometers. The present study performs a detailed dynamic and energetic analysis of two extreme rainfall events, two intense frost events, and three high-pollution events occurring on the Huancayo observatory between 2018 and 2019...Item Restricted Aperture-synthesis radar imaging with compressive sensing for ionospheric research(American Geophysical Union, 2019-06) Hysell, D. L.; Sharma, P.; Urco, M.; Milla, MarcoInverse methods involving compressive sensing are tested in the application of two-dimensional aperture-synthesis imaging of radar backscatter from field-aligned plasma density irregularities in the ionosphere. We consider basis pursuit denoising, implemented with the fast iterative shrinkage thresholding algorithm, and orthogonal matching pursuit (OMP) with a wavelet basis in the evaluation. These methods are compared with two more conventional optimization methods rooted in entropy maximization (MaxENT) and adaptive beamforming (linearly constrained minimum variance or often “Capon's Method.”) Synthetic data corresponding to an extended ionospheric radar target are considered. We find that MaxENT outperforms the other methods in terms of its ability to recover imagery of an extended target with broad dynamic range. Fast iterative shrinkage thresholding algorithm performs reasonably well but does not reproduce the full dynamic range of the target. It is also the most computationally expensive of the methods tested. OMP is very fast computationally but prone to a high degree of clutter in this application. We also point out that the formulation of MaxENT used here is very similar to OMP in some respects, the difference being that the former reconstructs the logarithm of the image rather than the image itself from basis vectors extracted from the observation matrix. MaxENT could in that regard be considered a form of compressive sensing.Item Restricted Broad plasma depletions detected in the bottomside of the equatorial F region: Simultaneous ROCSAT-1 and JULIA observations(American Geophysical Union, 2014-07-09) Kil, Hyosub; Kwak, Young‐Sil; Lee, Woo Kyoung; Oh, Seung-Jun; Milla, Marco; Galkin, IvanWe investigated the association of broad plasma depletions (BPDs) with plasma bubbles and ionospheric uplift in the equatorial F region using the coincident satellite and radar observations over Jicamarca in Peru. BPDs were detected by the first Republic of China satellite (ROCSAT-1) on the nights of 21 and 22 December 2002 during the period of moderate geomagnetic activity. The observations of the Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere radar and an ionosonde showed that the F peak height was lifted above the ROCSAT-1 altitude (600 km) at the times of the BPD detection. The fraction of NO+ was substantial at the locations of BPDs. These observations support the association of the BPDs with the ionospheric uplift. However, the absence of large backscatter plumes at the times of the BPD detection indicates that the BPDs were not produced by a single large bubble or a merger of bubbles.Item Open Access Calibrated radar observations of the equatorial mesosphere and ionosphere during an 11-day campaign(Instituto Geofísico del Perú, 2009) Kudeki, E.; Milla, Marco; Reyes, P.; Lehmacher, G.; Chau Chong Shing, Jorge Luis; Kuyeng, K. M.; De la Jara, CésarPresentado en MST12 - 12th Workshop on Technical and Scientific Aspects of MST Radars, London, Ontario, Canada, 17-23 May 2009.Item Open Access Climatology of mesosphere and lower thermosphere diurnal tides over Jicamarca (12°S, 77°W): observations and simulations(SpringerOpen, 2023-12-14) Suclupe, Jose; Chau, Jorge L.; Conte, Federico J.; Milla, Marco; Pedatella, N. M.; Kuyeng, KarimThis work shows a 3-year climatology of the horizontal components of the solar diurnal tide, obtained from wind measurements made by a multistatic specular meteor radar (SIMONe) located in Jicamarca, Peru (12°S, 77°W). Our observations show that the meridional component is more intense than the zonal component, and that it exhibits its maxima shifted with respect to the equinox times (i.e., the largest peak occurs in August–September, and the second one in April–May). The zonal component only shows a clear maximum in August–September. This observational climatology is compared to a climatology obtained with the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X). Average comparisons indicate that the model amplitudes are 50% smaller than the observed ones. The WACCM-X results are also used in combination with observed altitude profiles of the tidal phases to understand the relative contributions of migrating and non-migrating components. Based on this, we infer that the migrating diurnal tide (DW1) dominates in general, but that from June until September (November until July) the DE3 (DW2) may have a significant contribution to the zonal (meridional) component. Finally, applying wavelet analysis to the complex amplitude of the total diurnal tide, modulating periods between 5 and 80 days are observed in the SIMONe measurements and the WACCM-X model. These modulations might be associated to planetary waves and intraseasonal oscillations in the lower tropical atmosphere.Item Open Access Coherent and incoherent scatter radar study of the climatology and day-to-day variability of mean F-region vertical drifts and equatorial spread F(American Geophysical Union, 2016-02) Smith, J. M.; Rodrigues, F. S.; Fejer, B. G.; Milla, MarcoWe conducted a comprehensive analysis of the vertical drifts and equatorial spread F (ESF) measurements made by the Jicamarca incoherent scatter radar (ISR) between 1994 and 2013. The ISR measurements allowed us to construct not only updated climatological curves of quiet-time vertical plasma drifts but also time-versus-height maps of ESF occurrence over the past two solar cycles. These curves and maps allowed us to better relate the observed ESF occurrence patterns to features in the vertical drift curves than previously possible. We identified an excessively high occurrence of post-midnight F region irregularities during December solstice and low solar flux conditions. More importantly, we also found a high occurrence of ESF events during sudden stratospheric warming (SSW) events. We also proposed and evaluated metrics of evening enhancement of the vertical drifts and ESF occurrence, which allowed us to quantify the relationship between evening drifts and ESF development. Based on a day-to-day analysis of these metrics, we offer estimates of the minimum pre-reversal enhancement (PRE) peak (and mean PRE) values observed prior to ESF development for different solar flux and seasonal conditions. We also found that ESF irregularities can reach the altitudes at least as high as 800 km at the magnetic equator even during low solar flux conditions.Item Restricted Coherent MIMO to improve aperture synthesis radar imaging of field-aligned irregularities: first results at Jicamarca(Institute of Electrical and Electronics Engineers, 2018) Urco, Juan M.; Chau Chong Shing, Jorge Luis; Milla, Marco; Vierinen, Juha P.; Weber, TobiasMultiple-input multiple-output (MIMO) radar techniques make use of multiple transmitters and multiple receivers to improve the spatial characterization of targets. In the case where the Bragg scattering k → -vector can be assumed to be the same for all transmit-receive paths, MIMO methods can be seen as a way of increasing the number of effective receivers. In the last decades, there has been scientific interest in determining the spatial characteristics of ionospheric and atmospheric irregularities on the subtransmit beam scale, allowing the study of processes in their intrinsic scales, otherwise inaccessible using simple beamforming techniques. Interferometric methods, including aperture synthesis imaging, were used in the past with a single transmitter and multiple receivers [single-input multiple-output (SIMO)]. In this paper, we present the first implementation of MIMO techniques to improve the spatial resolution of aperture synthesis radar imaging of daytime equatorial electrojet irregularities observed using the Jicamarca Radio Observatory (JRO). Our implementation uses two spatially separated transmitters and four spatially separated receivers. In order to separate the contributions of each transmitter, time, code, and polarization diversity experiments have been tested. We find that all three diversity approaches can be used for ionospheric irregularities, but time and polarization diversity are not applicable in all situations due to the range and Doppler width of the echoes, and due to magnetoionic radio propagation effects. The results are evaluated by comparing new MIMO imaging results against the currently used SIMO imaging technique. We present and discuss the theoretical and practical aspects of the MIMO approach, so they can be applied to study other targets not only at JRO but also at other modular coherent scatter radars.Item Restricted Comparison of GB-SAR imaging algorithms for a landslide monitoring application(Institute of Electrical and Electronics Engineers, 2020-10-12) De la Cruz, Luis; Milla, MarcoA comparative analysis of three imaging algorithms for Ground Based Synthetic Aperture Radar (GB-SAR) systems has been conducted in order to select the most appropriate algorithm to be used in a landslide monitoring application. These algorithms are Frequency Domain Back Projection (FDBP), Range Migration Algorithm (RMA), and Discrete Linear Inverse Problem (DLIP). The comparison is based on image reconstruction quality, computational efficiency, and displacement measurement accuracy. Simulated and real data were used to test and compare the algorithms. Results show that FDBP is the most appropriate method for the proposed application.Item Open Access Compendio de investigaciones en geofísica: trabajos de investigación realizados por estudiantes durante el año 2015(Instituto Geofísico del Perú, 2015-12) Instituto Geofísico del Perú; Tavera, Hernando; Milla, Marco; Takahashi, KenEl arte de la publicación científica y técnica es cultivado en el IGP desde su historia temprana. Actualmente, el número de artículos en revistas internacionales indexadas y libros constituye uno de los principales indicadores de la producción institucional. La formación de los estudiantes en investigación científica y tecnológica incluye su adiestramiento en transmitir sus resultados de manera ordenada y rigurosa en artículos para su publicación. Este compendio representa el primer hito, alcanzado por los estudiantes autores de los artículos, de una larga y fructífera carrera en la investigación científica, desarrollo tecnológico que estamos seguros ellos emprenderán.Item Open Access Compendio de investigaciones en geofísica: trabajos de investigación realizados por estudiantes durante el año 2016(Instituto Geofísico del Perú, 2016-10) Instituto Geofísico del Perú; Tavera, Hernando; Takahashi, Ken; Milla, Marco; Martínez Grimaldo, AlejandraLa presente publicación tiene por objetivo la difusión de los diferentes trabajos realizados por ellos, trabajos que incluyen temas de investigación científica relacionados con ciencias de la tierra sólida, atmósfera e hidrósfera, aeronomía, astronomía, y disciplinas asociadas, así como también temas de ingeniería vinculados con desarrollo tecnológico, procesamiento de señales, tecnologías de la información, entre otros. Desde 1999, cuando se empieza a publicar el entonces denominado “Compendio de trabajos de investigación realizados por estudiantes del IGP”, este espacio se ha convertido en la carta de presentación de la cantera de estudiantes de la institución ante la comunidad científica nacional e internacional. En esta edición, correspondiente al volumen 17, se presentan 22 trabajos con el firme propósito de continuar siendo un aporte importante en el conocimiento y comprensión de la geofísica y ciencias afines.Item Open Access Compendio de investigaciones en geofísica: trabajos de investigación realizados por estudiantes durante el año 2017(Instituto Geofísico del Perú, 2017) Instituto Geofísico del Perú; Tavera, Hernando; Milla, Marco; Espinoza, Jhan CarloEn el presente compendio se pondrá en conocimiento de la sociedad diversas investigaciones desarrolladas en ámbitos de estudio como la sismología, vulcanología, aeronomía, física atmosférica, entre otros.Item Open Access Compendio de trabajos de investigación realizados por estudiantes durante los años 2013-2014(Instituto Geofísico del Perú, 2014-12) Instituto Geofísico del Perú; Tavera, Hernando; Takahashi, Ken; Milla, MarcoEl compendio adjunto reúne 26 artículos de investigación elaborados por estudiantes universitarios que realizaron sus estadías de investigación en el Instituto Geofísico del Perú. Las temáticas de los artículos giran en torno de diversos aspectos de la geofísica, tales como: ciencias de la atmósfera, ciencias de la tierra, ingeniería electrónica, física y estudios de la alta atmósfera.Item Open Access Concurrent observations at the magnetic equator of small-scale irregularities and large-scale depletions associated with equatorial spread F(American Geophysical Union, 2015-11-20) Hickey, Dustin A.; Martinis, Carlos R.; Rodrigues, Fabiano S.; Varney, Roger H.; Milla, Marco; Nicolls, Michael J.; Strømme, Anja; Arratia, Juan F.In 2014 an all-sky imager (ASI) and an Advanced Modular Incoherent Scatter Radar consisting of 14 panels (AMISR-14) system were installed at the Jicamarca Radio Observatory. The ASI measures airglow depletions associated with large-scale equatorial spread F irregularities (10's-100's km), while AMISR-14 detects small-scale irregularities (0.34 m). This study presents simultaneous observations of equatorial spread F (ESF) irregularities at 10-100 km scales using the all sky-imager, at 3 m scales using the JULIA (Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere) radar, and at 0.34 m scales using the AMISR-14 radar. We compare data from the three instruments on the night of 20-21 August, 2014 by locating the radar scattering volume in the optical images. During this night no topside plumes were observed, and we only compare with bottomside ESF. AMISR-14 had five beams perpendicular to the magnetic field covering ~200 km in the east-west direction at 250 km altitude. Comparing the radar data with zenith ASI measurements, we found that most of the echoes occur on the western wall of the depletions with fewer echoes observed the eastern wall and center, contrary to previous comparisons of topside plumes that showed most of the echoes in the center of depleted regions. We attribute these differences to the occurrence of irregularities produced at sub-meter scales by the lower-hybrid-drift instability. Comparisons of the ASI observations with JULIA images show similar results to those found in the AMISR-14 and ASI comparison.Item Open Access Construcción de un prototipo de radar meteorológico de banda X en el Perú(Instituto Geofísico del Perú, 2020-06) Espinoza, Juan C.; Valdez, Alexander; Ortecho, Daniel; Kuyeng, Karim; Scipión, Danny; Milla, MarcoSe presentan los avances en el desarrollo del primer prototipo de radar meteorológico de banda X completamente desarrollado en el Perú. El sistema es compacto y transportable y cuenta con una antena parabólica de 1.2m de diámetro de doble polarización instalada sobre un posicionador, que permite el movimiento en azimut y elevación. Además, los sistemas de transmisión y recepción del radar están basados en tecnologías SDR (Software Defined Radio) para mayor flexibilidad en su configuración. El objetivo del radar es realizar mediciones de las precipitaciones en una determinada región, cubriendo un área de varias decenas de kilómetros alrededor del radar para así poder realizar investigaciones sobre las condiciones atmosféricas en esta región. La construcción de este prototipo viene siendo realizada por el Instituto Geofísico del Perú, en su sede del Radio Observatorio de Jicamarca, y es financiada por el fondo para intervenciones ante la ocurrencia de desastres naturales (FONDES) del Instituto Nacional de Defensa Civil (INDECI).Item Restricted Data-driven numerical simulations and forecasts of equatorial spread F in the Peruvian sector(Instituto Geofísico del Perú, 2014-08) Hysell, D. L.; Milla, Marco"Ionospheric state parameters including plasma number density and vector drift profiles were measured at the Jicamarca Radio Observatory during campaigns throughout 2013. Neutral winds were measured by the redline Fabry Perot interferometer at Jicamarca. Coherent radar backscatter from plasma irregularities associated with equatorial spread F (ESF) was also recorded. Radar imagery of the morphology of the large-scale ESF irregularities is also available from simultaneous measurements. A 3D numerical simulation of ionospheric irregularities, initialized and forced using parametrizations derived from a combination of measurements and empirical models, has been used to reproduce the ESF activity that occurred on a number of different, representative campaign nights. The simulations were able to recover many of the most salient features of the irregularities that formed in each case. The campaign data, numerical simulations, and protocols used to associate them are presented."