Browsing by Author "Scipión, Danny"
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Item Restricted A storm-time global electron density reconstruction model in three-dimensions based on artificial neural networks(Elsevier, 2024-02-16) Habarulema, John Bosco; Okoh, Daniel; Burešová, Dalia; Rabiu, Babatunde; Scipión, Danny; Häggström, Ingemar; Erickson, Philip J.; Milla, Marco A.We present results of a dedicated global storm-time model for the reconstruction of ionospheric electron density in three-dimensions. Using the storm criterion of |Dst| ≥ 50 nT and Kp ≥ 4, the model is constructed using a combination of radio occultation and ionosonde data during the periods of 2006–2021 and 2000–2020, respectively. From the ionosonde data, only the bottomside electron density profiles up to the maximum height of the F2 layer (hmF2) are considered. In addition to the selection of storm-time data only for the model development, we have investigated the inclusion of time history for the geomagnetic storm indicator Kp at 9 and 33 h in an attempt to take into account the delay of physical processes related to atmospheric gravity waves or traveling ionospheric disturbances and thermospheric composition changes which drive varying ionospheric storm effects during storm conditions. Based on incoherent scatter radar data and in comparison with the IRI 2020 model, the developed storm-time model provides foF2 modelling improvement of above 50% during the storm main phase over Millstone Hill (42.6°N, 71.5°W) and Tromsø (69.6°N, 19.2°E) for the storm periods of 3–6 November 2021 and 23–25 March 2023, respectively. Modelled results for Jicamarca (11.8°S, 77.2°W) show that the storm-time model estimates foF2 by an improvement of over 20% during the main phase of the 07–10 September 2017 storm period. As the ionospheric conditions return to quiet time levels, the IRI 2020 model perform better than the constructed storm -time model.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 Open Access Building resilience in flood disaster management in northern Peru(Instituto Geofísico del Perú, 2020) Instituto Geofísico del Perú; Birmingham City University; Scipión, Danny; Silva Vidal, Yamina; Kapetas, Leon; Grace, Mike; Lim, Andy; Wall, Roger; Proverbs, DavidThis report provides a detailed account of the Newton Fund Peru Researcher Links Workshop held between 20th and 23rd August 2018 in Piura, Peru, entitled ‘Building Resilience in Flood Disaster Management in Northern Peru’. The report provides some background to the workshop, the aim and objectives, problem definition, as well as an account of the workshop process and key workshop findings and recommendations. The workshop was run jointly by Birmingham City University (BCU) in partnership with Instituto Geofísico del Perú (IGP) and was hosted by the Universidad de Piura (UDEP). The workshop was a response to the severe flooding experienced in Piura during the El Niño event of March 2017 which caused a number of fatalities, damaged over 100,000 homes and destroyed much local infrastructure including around 100 bridges. El Niño is a recurrent event and there is concern that its frequency and intensity may change in the future as a consequence of climate change. Six key and integrated themes emerged from the workshop activities as: i) Governance; ii) Risk Information; iii) Healthy Communities; iv) Infrastructure; v) Urban and regional planning; and vi) the River System. For each of these themes, the report provides an overview of the problem as well as some detailed suggestions and recommendations for addressing the difficulties and challenges identified.Item Open Access Characterization of the convective boundary layer through a combination of large-eddy simulations and a radar simulator(University of Oklahoma, 2011) Scipión, Danny; Palmer, Robert; Chilson, PhillipThe boundary layer (BL) is the lowest part of the atmosphere where the flow field is directly influenced by interactions among air, heat, and the Earths surface. The structure of flow in the BL is dynamic due to the fact that the atmospheric flow is turbulent. Turbulence in the daytime convective boundary layer (CBL) is primarily caused by buoyancy forced from the heated underlying surface. Wind profilers are one of the many instruments used to study and characterize the atmosphere. In addition to in-situ observations, numerical large-eddy simulations (LES) have been probed to adequately reproduce the CBL under different conditions. The focus of this work is to bring the advantages of LES techniques to assist in the interpretation of data from wind profilers. The present study focuses on an example of flow structure of the CBL as observed in the U.S. Southern Great Plains Atmospheric Radiation Measurement Climate Research Facility in Lamont, Oklahoma on June 8, 2007. The considered CBL flow has been reproduced using LES, sampled with a LES-based virtual boundary layer radar (BLR), and probed with an actual operational wind profiler. The LES-generated CBL flow data are then ingested by the virtual BLR and treated as a proxy for prevailing atmospheric conditions. The virtual BLR has been used to simulate radar signals obtained from wind profilers through the synthesis of Doppler beam swinging (DBS) and spaced antenna (SA) techniques and to retrieve the three-dimensional wind fields. Comparisons of the estimates of the structure parameter of refractive index [special characters omitted], wind fields, vertical velocity variance, and vertical velocity skewness have been presented for the LES, virtual BLR, and actual radar. It has been observed that during the presence of strong horizontal shear of vertical velocity, the estimates of the horizontal wind fields are biased. This study will quantify the effect of this shear for both wind estimation techniques under different conditions. Additionally, it has been noticed that this shear also biases the estimates of turbulence kinetic energy (TKE) calculated from the variances of the wind fields. Finally, the TKE (eddy) dissipation rate ε can be obtained from radar estimates of Doppler spectral width. Values of ε are obtained from the different oblique and vertical beams and contrasted with the LES estimates obtained through a parameterized expression that relates the dissipation rate to sub-grid TKE and turbulence length scale.Item Restricted CLAIRE: An UHF wind profiler radar for turbulence and precipitation studies(Institute of Electrical and Electronics Engineers, 2017-01-16) Oscanoa, Julio; Castillo, Cristiam; Scipión, DannyDue to diverse and extreme weather conditions, the Peruvian population is vulnerable to high-impact natural disasters. A continuous monitoring of all weather conditions is necessary for accurate weather models, forecast, and nowcast along the territory. To cope with this problem, the Jicamarca Radio Observatory (JRO) is developing a low-cost, portable CLear AIr and Rainfall Estimations (CLAIRE) Radar that will provide tropospheric winds, turbulence, and rainfall estimations that will help analyze and quantify meteorological phenomena. CLAIRE consists of four Yagi-Uda antenna phased arrays, one for transmission and three for reception, arranged in a quasimonostatic system. The 445-MHz CLAIRE system is sensitive to both clear-air and precipitation echoes. The aim is to separate the two types of echoes through spectral analysis and process them independently. For the wind and turbulence measurements, Spaced Antenna technique will be applied, while precipitation measurements will be obtained by analyzing the corresponding radar reflectivity factor (Ze).Item Restricted Climatology of Equatorial F-Region UHF Coherent Backscatter Radar Echoes and Comparison with Collocated VHF Radar Observations(IEEE, Institute of Electrical and Electronics Engineers, 2024) Massoud, A. A.; Rodrigues, F. S.; Sousasantos, J.; Milla, M. A.; Scipión, Danny; Apaza, J. M.; Kuyeng, Karim; Padin, C.Equatorial ionospheric irregularities at meter scale sizes have been well-studied using Very High Frequency (VHF) radar systems at the Jicamarca Radio Observatory (JRO). For example, the Jicamarca Unattended Long-Term Studies of the Ionosphere and Atmosphere (JULIA) is a 50 MHz coherent scatter radar system and has operated routinely since 1996. Radio waves transmitted by JULIA reflect off of field-aligned irregularities with scale sizes of ~3-meters due to Bragg scattering. Recently, the deployment and later repair of an Ultra High Frequency (UHF) radar system at the JRO provided an opportunity for coherent backscatter radar studies of irregularities with sub-meter scale sizes. The 14-panel version of the Advanced Modular Incoherent Scatter Radar (AMISR-14) system makes measurements at 445 MHz, corresponding to measurements of previously unobserved ~34-centimeters equatorial irregularities.Item Open Access Clustering and data reduction algorithm applied to spectra measured with a multi-static HF sounding system in Peru(2023 CEDAR Workshop, 2023-06) Vásquez, V.; Milla, M.; Kuyeng, Karim; Gonzales, J.; Scipión, DannyThe HF radar is a network of HF radio beacons and receivers for ionospheric sounding, and it has been operating in Peru since 2016. The purpose of this instrument is to measure the group delay, Doppler shift, power, and other parameters in order to estimate the regional plasma density as a function of space and time. This information is crucial for forecasting the occurrence of Spread-F. To improve the quality of the spectral data, two changes were made. The first one involved transmitting frequencies separated by 3.3 Hz in each transmission station, which allowed to spectrally separate and identify the signals coming from a given station, displacing the cross-talk in frequency but not eliminating it. Therefore, the second change was made, which corresponds to the development of an algorithm that extracts only the signals of interest from the measured spectrum. It is capable of detecting clusters of data in the spectra classifying them as coherent echoes, while noise sectors are discarded. The algorithm procedure and the comparisons of the spectra and final data are shown in this work.Item Open Access Combined radar observations of equatorial electrojet irregularities at Jicamarca(European Geosciences Union (EGU), 2007-03-08) Hysell, D. L; Drexler, J.; Shume, E. B; Chau Chong Shing, Jorge Luis; Scipión, Danny; Vlasov, M.; Cuevas, R.; Heinselman, C.Daytime equatorial electrojet plasma irregularities were investigated using five distinct radar diagnostics at Jicamarca including range-time-intensity (RTI) mapping, Faraday rotation, radar imaging, oblique scattering, and multiple-frequency scattering using the new AMISR prototype UHF radar. Data suggest the existence of plasma density striations separated by 3–5 km and propagating slowly downward. The striations may be caused by neutral atmospheric turbulence, and a possible scenario for their formation is discussed. The Doppler shifts of type 1 echoes observed at VHF and UHF frequencies are compared and interpreted in light of a model of Farley Buneman waves based on kinetic ions and fluid electrons with thermal effects included. Finally, the up-down and east-west asymmetries evident in the radar observations are described and quantified.Item Open Access Compendio de investigaciones en geofísica: trabajos de investigación realizados por estudiantes durante los años 2018-2019(Instituto Geofísico del Perú, 2020-06) Instituto Geofísico del Perú; Scipión, Danny; Gómez Avalos, Juan Carlos; Silva Vidal, YaminaEl Instituto Geofísico del Perú (IGP) tiene como su principal función realizar investigación científica en el campo de la geofísica, sea teórica o aplicada, pero siempre buscando su valor público como el mayor aporte que se hace a la sociedad. La información que resulta de estas investigaciones dan lugar a informes y reportes técnicos, así como a publicaciones en revistas científicas indexadas; siendo nuestro interés que la información llegue a los usuarios primarios para concluir con la cadena de generación del conocimiento. Para cumplir con esta función, el IGP siempre ha contado con un grupo importante de investigadores con diferentes especialidades en el campo de la geofísica, los mismos que además, cada año asumen la responsabilidad de formar y guiar a profesionales jóvenes en el fascinante mundo de la investigación, liderando proyectos de corta duración y cuyos resultados requieren ser publicados. En este marco, el IGP publica el “Compendio de Estudiantes”, que desde su primer año se ha constituido como el mayor instrumento institucional que publica los aportes logrados por profesionales jóvenes durante la elaboración de sus tesis profesionales, pasantías y prácticas pre-profesionales desarrolladas en los diversos programas de investigación de la institución. De este modo, estos profesionales, con la asesoría de nuestros investigadores, logran obtener sus títulos y/o culminar sus informes de pasantías o prácticas pre-profesionales, siendo estos logros la base para formar profesionales encaminados en la investigación científica, lo cual contribuye al desarrollo de la ciencia en el país.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 Open Access Dataset on the first weather radar campaign over Lima, Perú(Elsevier, 2021-04) Valdivia Prado, Jairo Michael; Scipión, Danny; Milla, Marco; Prado, Josep J.; Espinoza, Juan C.; Cordova, Darwin; Saavedra Huanca, Miguel; Villalobos Puma, Elver Edmundo; Callañaupa Gutierrez, Stephany Magaly; Silva Vidal, YaminaThe first weather radar campaign over Lima, the capital of Peru, a desertic area on the western side of the Peruvian Andes, was carried out to study the occurrence of rain events in summer 2018. The weather radar was installed strategically and was able to overlook three river basins: Rimac, Chillón, and Lurin. An X-band radar (PX-1000) was used, which operates at 9.55 GHz. PX-1000 was built by the Advanced Radar Research Center (ARRC) at the University of Oklahoma (U.S.A.). The radar operated from January 26th to April 1st, 2018, at Cerro Suche located 2910 m ASL and 55 km from the city of Lima. The PX-1000 performed plan-position indicators (PPI) for elevations starting at 0° up to 20°. The data presented here were obtained using a three-dimensional constant-altitude plan position-indicator (3D CAPPI), which was generated by high resolution (250 m) nearest point algorithm.Item Open Access Daytime vertical and zonal velocities from 150-km echoes over Jicamarca(Instituto Geofísico del Perú, Radio Observatorio de Jicamarca, 2004-06-27) Chau Chong Shing, Jorge Luis; Woodman Pollitt, Ronald Francisco; Scipión, DannyDoppler velocities of 150-km echoes represents the vertical ExB drift velocities at F region altitudes. 150-km observations represent and excelent mean of monitoring the electric fields at equatorial latitudes. Low power observations of 150-km echoes using the JULIA system have been carried out almost continuosly since August 2001 at Jicamarca [e.g., Anderson et al., 2004]. Most of the observations have been done pointing perpendiculat to the magnetic fiel (B) in the magnetic meridian, allowing the measurement of the vertical component of the ExB drift.Item Restricted Detection and characterization of the melting layer based on polarimetric radar scans(Wiley, 2015-09-22) Wolfensberger, Daniel; Scipión, Danny; Berne, AlexisStratiform rain situations are generally associated with the presence of a melting layer characterized by a strong signature in polarimetric radar variables. This layer is an important feature as it indicates the transition from solid to liquid precipitation. The melting layer remains poorly characterized, particularly from a polarimetric radar point of view. In this work a new algorithm to automatically detect the melting layer on polarimetric RHI radar scans using gradients of reflectivity and copolar correlation is first proposed. The algorithm was applied to Xband polarimetric radar data and validated by comparing the height of the detected layer with freezing levels heights obtained from radiosoundings and was shown to give both small errors and bias. The algorithm was then used on a large selection of precipitation events (more than 4000 RHI scans) from different seasons and climatic regions (South of France, Swiss Alps and plateau and Iowa-USA) to characterize the geometric and polarimetric signatures of the melting layer. The melting layer is shown to have a very similar geometry on average, independently of the topography and climatic conditions. Variations in the thickness of the melting layer during and between precipitation events was shown to be strongly related to the presence of rimed particles, to the vertical velocity of hydrometeors and to the intensity of the bright band.Item Open Access Development of a radiofrequency signal generator for ionosonde radar transmitter using low-cost SDR(2023 SWOL Workshop, 2023-10) Estalla, B.; Milla, M.; Verastegui, J.; Espinoza, J.; Scipión, DannyThe Jicamarca Radio Observatory (JRO) is an Instituto Geofísico del Perú (IGP) facility, dedicated to monitor the upper atmosphere with different instruments such as radars, GNSS receivers, magnetometers, among others. Ionosonde is a type of HF radar that uses multiple frequencies to survey the ionosphere and obtain estimates of electron density. In this poster we present the development of a low-cost radiofrequency signal generator for a ionosonde radar transmitter based on the Red Pitaya development board with a sampling frequency of 250 Msps, and the ability to transmit modulated signals with a frequency sweep ranging from 1 MHz to 60 MHz, providing the possibility of using it with other CW radars.Item Restricted Development of two UAVs for volcano studies in southern Peru(Institute of Electrical and Electronics Engineers, 2017-10) Apaza, Joab; Scipión, Danny; Lume, Diego; Saito, CarlosThe development of Unmanned Aerial Vehicles (UAVs) has gained importance over the last few years due to the innovations brought to farming, architecture, and/or medicine. A novel field where they have been used is volcanology for its long-distance control and the possibility to add multiple sensors for sensing volcano parameters. Two UAVs will be constructed: a multi-rotor (quadcopter) and a fix wing airplane for studying the most active volcano in Peru, the Ubinas. The objective is to get important and useful volcano data without risking the lives of researchers. The quadcopter will be used for image capturing and video recording of the plume, while the airplane will fly close or through to the volcanic plume measuring temperature, humidity, carbon dioxide, sulfuric dioxide, and hydrogen sulfide.Item Open Access Diseño de módulos de generación, conversión de frecuencia, amplificación y sincronización para un radar perfilador de vientos que opera a 445 mhz(Pontificia Universidad Católica del Perú, 2015-12) Castillo, Cristiam; Scipión, DannyEl Radio Observatorio de Jicamarca (ROJ) es un centro de investigación ubicado a 25 km. Al este de la ciudad de Lima. Durante más de 54 años ha proporcionado información científica en base a radar y ondas de radio que han sido relevantes para el desarrollo de la física ionosféricos, física del plasma y dinámica atmosférica. El ROJ busca constantemente expandir sus capacidades técnicas y científica. En esas circunstancias el ROJ busca implementar un radar perfilador de vientos que opera a 445 MHz con el fin de proporcionar a la comunidad científica un instrumento de investigación troposférica. Este radar entregaría información valiosa sobre velocidad de vientos y sobre precipitaciones que podrían atenuar el impacto de los fenómenos atmosféricos en la población peruana. Para lograrlo, el ROJ plantea aprovechar al máximo los conocimientos y tecnologías adquiridos en radares y de esa forma generar localmente la tecnología y recursos humanos para el desarrollo de este proyecto. En base a esa necesidad, la presente tesis desarrolla el análisis y diseño de los módulos generación de señal, conversión de frecuencia, amplificación y filtrado y reloj para un radar que opera 445 MHz y que permita aprovechar los equipos, conocimientos y tecnologías actuales del ROJ.Item Open Access Diseño del sistema de automatización y supervisión para el encendido del transmisor del radar SOUSY en el Radio Observatorio de Jicamarca(Pontificia Universidad Católica del Perú, 2015-07) Florentino, André; Scipión, Danny; Milla, MarcoEl presente documento de tesis describe el proceso seguido para el diseño del sistema de automatización y supervisión para el encendido del transmisor del radar SOUSY (ubicado en el Radio Observatorio de Jicamarca) usando tecnologías de control estándares actuales. Para llevar a cabo el diseño, primero se estudio el procedimiento de encendido original. El análisis de los circuitos que controlan el encendido del transmisor permitido identificar cuáles y cuántas eran las señales de control existentes, y además conocer su interrelación para realizar el control. Posteriormente, se pasó a seleccionar un dispositivo de control adecuado a las necesidades propias del sistema y teniendo en cuenta que era necesario un medio de visualización que permitirá, además, la rápida identificación de errores en el proceso de encendido del transmisor. Luego de escoger el dispositivo de control y el medio de supervisión, se procedió al diseño el sistema de encendido en base a la secuencia original, la cual era controlada por dispositivos electromecánicos y temporizadores. Asimismo, la visualización fue elaborada con la colaboración de los usuarios finales, de tal manera que esté de acuerdo a sus requerimientos y necesidades de uso. Finalmente, las simulaciones del encendido y visualización fueron realizadas en el entorno llamado CoDeSys, el cual fue usado para la implementación del sistema. El sistema fue evaluado simulando ciertas situaciones de funcionamiento (sugeridas por el personal de operación del radar) con el fin de probar su compatibilidad. Con esto se determinó que, tanto el sistema de encendido, Así como el de visualización respondan adecuadamente ante las situaciones críticas, y que el sistema se encuentra apto para ser probado en el transmisor, siempre y cuando se haya establecido un protocolo de seguridad para las pruebas.Item Open Access Diseño e implementación de una estación de recarga autónoma para un vehículo aéreo no tripulado para el monitoreo de volcanes(Universidad Nacional del Callao, 2017-02) Morales, Alessandro; Cruz Ramírez, Armando; Scipión, DannySe enviará un vehículo aéreo no tripulado al cráter del volcán Ubinas (5672 m.s.n.m.) para estudiar y caracterizar la actividad volcánica, mediante la captura de fotos y videos a través de una cámara óptica y una cámara térmica. Este vehículo sólo proporciona una autonomía de vuelo de máximo 20 minutos, principalmente debido al alto consumo energético que se genera por la baja densidad de aire que se encuentra a esta altura. Ya que este tiempo no es el suficiente para completar la ruta de vuelo deseada; se plantea el diseño y la implementación de un sistema de recarga de energía para garantizar que el vehículo aéreo no tripulado complete la misión de monitorear el volcán. Dados los riesgos que implica el desarrollo de labores cerca del volcán por parte de personal técnico y científico, se diseña el sistema para que opere con la menor intervención humana posible. Además, se analiza la trayectoria de vuelo para determinar el consumo de energía del dron y la ubicación del sistema de recarga. Finalmente, se detalla el diseño e implementación del sistema y se describen las recomendaciones para su operación.Item Open Access Estimados de energía cinética turbulenta (TKE) y factor de disipación obtenidos con perfilador de vientos virtual y verificados a través de simulaciones de remolinos grandes(Instituto Geofísico del Perú, 2010) Scipión, Danny; Fedorovich, E.; Palmer, R.; Chilson, P.; Botnick, A.Diapositivas presentadas en el XIII Encuentro Científico Internacional, (ECI 2010v), realizado del 5 al 8 de enero de 2010 en la ciudad de Lima.Item Open Access First climatology of F-region UHF echoes observed by the AMISR-14 system at the Jicamarca radio observatory and comparison with the climatology of VHF echoes observed by the collocated JULIA radar(Elsevier, 2024-10) Massoud, Alexander A.; Rodrigues, Fabiano S.; Sousasantos, Jonas; Milla, Marco A.; Scipión, Danny; Apaza, Joab M.; Kuyeng, Karim; Padin, CarlosCoherent backscatter radar observations made at the Jicamarca Radio Observatory (JRO) have contributed significantly to our understanding of equatorial F-region irregularities. Radar observations, however, have been made predominantly at the Very-High Frequency (VHF) band (50 MHz), which corresponds to measurements of 3-m field-aligned irregularities. The deployment of the 14-panel version of the Advanced Modular Incoherent Scatter Radar (AMISR-14) at Jicamarca provided an opportunity for observations of Ultra-High Frequency (UHF - 445 MHz) echoes which correspond to measurements of irregularities with 0.34 m scale sizes. Here, we present what we believe to be the first report describing the quiet-time climatology of sub-meter equatorial F-region irregularities derived from UHF radar measurements. The measurements were made between August 2021 and February 2023 using a 10-beam AMISR-14 mode that scanned the F-region in the magnetic equatorial plane. The results show how F-region sub-meter irregularities respond to variations in season and solar flux conditions. The results also confirm, experimentally, that the occurrence of UHF F-region echoes is controlled by the occurrence of equatorial spread F (ESF). Higher occurrence rates were observed during pre-midnight hours and during Equinox and December solstice. Reduced occurrence rates were observed during June solstice. The results show that an increase in solar flux was followed by an increase in the altitude where noticeable occurrence rates start and in the maximum altitude of these occurrence rates. The observations also show that occurrence rates lasted longer (in local time) during low solar flux conditions. Comparisons with collocated VHF radar observations showed that, despite differences in radar parameters, observation days, and the scale size (one order of magnitude) of the scattering irregularities, the two systems show similar climatological variations with only minor differences in the absolute occurrence rates. Finally, the analysis of the occurrence rates for different beams did not show substantial climatological variations over local (within a few 100s of km) zonal distances around JRO. We point out, however, that observations on a single day can show strong local variations in echo detection and intensity within the AMISR-14 field of view due to the intrinsic development and decay of ESF structures.
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