Artículos Científicos
Permanent URI for this collection
Browse
Recent Submissions
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.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 Embargo Mesosphere and Lower Thermosphere Wind Perturbations Due To the 2022 Hunga Tonga-Hunga Ha'apai Eruption as Observed by Multistatic Specular Meteor Radars(American Geophysical Union, 2024-08-06) Chau, Jorge L.; Poblet, Facundo L.; Liu, Hanli; Liu, Alan; Gulbrandsen, Njål; Jacobi, Christoph; Rodriguez, Rodolfo R.; Scipión, Danny; Tsutsumi, MasakiUtilizing multistatic specular meteor radar (MSMR) observations, this study delves into global aspects of wind perturbations in the mesosphere and lower thermosphere (MLT) from the unprecedented 2022 eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) submarine volcano. The combination of MSMR observations from different viewing angles over South America and Europe, and the decomposition of the horizontal wind in components along and transversal to the HTHH eruption's epicenter direction allow an unambiguous detection and identification of MLT perturbations related to the eruption. The performance of this decomposition is evaluated using Whole Atmosphere Community Climate Model with thermosphere/ionosphere extension (WACCM-X) simulations of the event. The approach shows that indeed the HTHH eruption signals are clearly identified, and other signals can be easily discarded. The winds in this decomposition display dominant Eastward soliton-like perturbations observed as far as 25,000 km from HTHH, and propagating at 242 m/s. A weaker perturbation observed only over Europe propagates faster (but slower than 300 m/s) in the Westward direction. These results suggest that we might be observing the so-called Pekeris mode, also consistent with the L1 pseudomode, reproduced by WACCM-X simulations at MLT altitudes. They also rule out the previous hypothesis connecting the observations in South America to the Tsunami associated with the eruption because these perturbations are observed over Europe as well. Despite the progress, the L0 pseudomode in the MLT reproduced by WACCM-X remains elusive to observations.Item Open Access Multi-process driven unusually large equatorial perturbation electric fields during the April 2023 geomagnetic storm(Frontiers Media, 2024-02-05) Fejer, Bela G.; Laranja, Sophia R.; Condor Patilongo, PercyThe low latitude ionosphere and thermosphere are strongly disturbed during and shortly after geomagnetic storms. We use novel Jicamarca radar measurements, ACE satellite solar wind, and SuperMAG geomagnetic field observations to study the electrodynamic response of the equatorial ionosphere to the 23, 24 April 2023 geomagnetic storm. We also compare our data with results from previous experimental and modeling studies of equatorial storm-time electrodynamics. We show, for the first time, unusually large equatorial vertical and zonal plasma drift (zonal and meridional electric field) perturbations driven simultaneously by multi storm-time electric field mechanisms during both the storm main and recovery phases. These include daytime undershielding and overshielding prompt penetration electric fields driven by solar wind electric fields and dynamic pressure changes, substorms, as well as disturbance dynamo electric fields, which are not well reproduced by current empirical models. Our nighttime measurements, over an extended period of large and slowly decreasing southward IMF Bz, show very large, substorm-driven, vertical and zonal drift fluctuations superposed on large undershield driven upward and westward drifts up to about 01 LT, and the occurrence of equatorial spread F irregularities with very strong spatial and temporal structuring. These nighttime observations cannot be explained by present models of equatorial storm-time electrodynamics.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 The impact of the Hunga Tonga–Hunga Ha’apai volcanic eruption on the Peruvian atmosphere: from the sea surface to the ionosphere(SpringerOpen, 2024-05-28) Pacheco, Edgardo E.; Velasquez, J. P.; Flores, R.; Condori, L.; Fajardo, G.; Kuyeng, Karim; Scipión, Danny; Milla, M.; Conte, J. F.; Poblet, F. L.; Chau, J. L.; Suclupe, J.; Rojas, R.; Manay, E.The eruption of the Hunga Tonga Hunga Ha’apai volcano on 15 January 2022 significantly impacted the lower and upper atmosphere globally. Using multi-instrument observations, we described disturbances from the sea surface to the ionosphere associated with atmospheric waves generated by the volcanic eruption. Perturbations were detected in atmospheric pressure, horizontal magnetic field, equatorial electrojet (EEJ), ionospheric plasma drifts, total electron content (TEC), mesospheric and lower thermospheric (MLT) neutral winds, and ionospheric virtual height measured at low magnetic latitudes in the western South American sector (mainly in Peru). The eastward Lamb wave propagation was observed at the Jicamarca Radio Observatory on the day of the eruption at 13:50 UT and on its way back from the antipodal point (westward) on the next day at 07:05 UT. Perturbations in the horizontal component of the magnetic field (indicative of EEJ variations) were detected between 12:00 and 22:00 UT. During the same period, GNSS-TEC measurements of traveling ionospheric disturbances (TIDs) coincided approximately with the arrival time of Lamb and tsunami waves. On the other hand, a large westward variation of MLT winds occurred near 18:00 UT over Peru. However, MLT perturbations due to possible westward waves from the antipode have not been identified. In addition, daytime vertical plasma drifts showed an unusual downward behavior between 12:00 and 16:00 UT, followed by an upward enhancement between 16:00 and 19:00 UT. Untypical daytime eastward zonal plasma drifts were observed when westward drifts were expected. Variations in the EEJ are highly correlated with perturbations in the vertical plasma drift exhibiting a counter-equatorial electrojet (CEEJ) between 12:00 and 16:00 UT. These observations of plasma drifts and EEJ are, so far, the only ground-based radar measurements of these parameters in the western South American region after the eruption. We attributed the ion drift and EEJ perturbations to large-scale thermospheric wind variations produced by the eruption, which altered the dynamo electric field in the Hall and Pedersen regions. These types of multiple and simultaneous observations can contribute to advancing our understanding of the ionospheric processes associated with natural hazard events and the interaction with lower atmospheric layers.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 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 On the detection of a solar radio burst event that occurred on 28 August 2022 and its effect on GNSS signals as observed by ionospheric scintillation monitors distributed over the American sector(EDP Open, 2023-11-28) Wright, Isaac G.; Rodrigues, Fabiano S.; Gomez Socola, Josemaria; Moraes, Alison O.; Monico, João F. G.; Sojka, Jan; Scherliess, Ludger; Layne, Dan; Paulino, Igo; Buriti, Ricardo A.; Brum, Christiano G. M.; Terra, Pedrina; Deshpande, Kshitija; Vaggu, Pralay R.; Erickson, Philip J.; Frissell, Nathaniel A.; Makela, Jonathan J.; Scipión, DannyAs part of an effort to observe and study ionospheric disturbances and their effects on radio signals used by Global Navigation Satellite Systems (GNSS), alternative low-cost GNSS-based ionospheric scintillation and total electron content (TEC) monitors have been deployed over the American sector. During an inspection of the observations made on 28 August 2022, we found increases in the amplitude scintillation index (S4) reported by the monitors for the period between approximately 17:45 UT and 18:20 UT. The distributed, dual-frequency observations made by the sensors allowed us to determine that the increases in S4 were not caused by ionospheric irregularities. Instead, they resulted from Carrier-to-Noise (C/No) variations caused by a solar radio burst (SRB) event that followed the occurrence of two M-class X-ray solar flares and a Halo coronal mass ejection. The measurements also allowed us to quantify the impact of the SRB on GNSS signals. The observations show that the SRB caused maximum C/No fadings of about 8 dB-Hz (12 dB-Hz) on L1 ~ 1.6 GHz (L2 ~ 1.2 GHz) for signals observed by the monitor in Dallas for which the solar zenith angle was minimum (~24.4°) during the SRB. Calculations using observations made by the distributed monitors also show excellent agreement for estimates of the maximum (vertical equivalent) C/No fadings in both L1 and L2. The calculations show maximum fadings of 9 dB-Hz for L1 and of 13 dB-Hz for L2. Finally, the results exemplify the usefulness of low-cost monitors for studies beyond those associated with ionospheric irregularities and scintillation.Item Open Access On new two-dimensional UHF radar observations of equatorial spread F at the Jicamarca Radio Observatory(Springer Open, 2023-08-09) Rodrigues, F.S.; Milla, M.A.; Scipión, Danny; Apaza, Joab; Kuyeng, Karim; Sousasantos, J.; Massoud, A.A.; Padin, C.We describe a mode for two-dimensional UHF (445 MHz) radar observations of F-region irregularities using the 14-panel version of the advanced modular incoherent scatter radar (AMISR-14). We also present and discuss examples of observations made by this mode. AMISR-14 is installed at the Jicamarca Radio Observatory (JRO, 11.95°S, 76.87°W, ~ 0.5° dip latitude) in Peru and, therefore, allows studies of ionospheric irregularities at the magnetic equator. The new mode takes advantage of the electronic beam-steering capability of the system to scan the equatorial F-region in the east–west direction. Therefore, it produces two-dimensional views of the spatial distribution of sub-meter field-aligned density irregularities in the magnetic equatorial plane. The scans have a temporal resolution of 20 s and allow observations over a zonal distance of approximately 400 km at main F-region heights. While the system has a lower angular and range resolution than interferometric in-beam VHF radar imaging observations available at Jicamarca, it allows a wider field-of-view than that allowed with the VHF system. Here, we describe the mode, and present and discuss examples of observations made with the system. We also discuss implications of these observations for studies of ESF at the JRO.Item Restricted Digital receiver modernization using FPGA and JESD204B interface for SDR applications(IEEE, Institute of Electrical and Electronics Engineers, 2023) Verástegui, Joaquín; Rojas, John; Tupac, Isaac; Gonzales, LuisThe latest data acquisition system running at the Jicamarca Radio Observatory (JRO) for the main radar has been used for more than seven years now. Although there are no major inconveniences on the performance, there have been some problems with internal interference which are related to the PCB design that uses old discrete components. A new design is proposed for the digital receivers, giving it more lifetime and flexibility for future modifications. The JESD204B protocol is ideal for radar applications, a JESD204B ADC together with an FPGA was proposed for the new design, making it capable of a wider bandwidth which could adapt the system to an SDR device in the future with the proper software. This paper will present the new PCB design, the IP cores implemented for the FPGA and some preliminary tests with development boards.Item Open Access Inferring Zonal Wind Profiles in the Equatorial Electrojet From Coherent Scatter(URSI, 2022-10-16) Hysell, D.L.; Chau, J.L.; Conte, J.F.; Flores, Roberto; Milla, M.A.Zonal wind estimates in the equatorial electrojet derived from coherent scatter echoes, specular meteor trail echoes, and optical limb scans are compared. While the three techniques exhibit broad overall agreement, significant differences in the results of the three techniques appear. The differences can be attributed in large part to horizontal inhomogeneity in the winds and the dissimilar averaging kernels of the three techniques.Item Open Access Seeing measurements at OAUNI on 2016 and 2017 campaigns(IOP Publishing, 2022) Pereyra, Antonio; Tello, J.; Zevallos, M.We present seeing measurements at OAUNI site gathered on 2016 and 2017 campaigns using V and R broadband filters. In order to quantify the seeing we used the full-width-at-half-maximum from stellar profiles on photometric sequences during the observational windows of our supernovae program. A typical median seeing of 1” .8 was found on 2016 and a worst value of 2” .0 on 2017. The last one was probably affected by anomalous conditions related to the 2017 extreme climatic event. The monthly first quartile analysis indicates that best seeing conditions can be achieved at a level of 1” .5. In general, our results indicate a reasonable sky quality for the OAUNI site.Item Open Access Driving Influences of the Doppler Flash Observed by SuperDARN HF Radars in Response to Solar Flares(American Geophysical Union, 2022-06) Chakraborty, S.; Qian, L.; Baker, J. B. H.; Ruohoniemi, J. M.; Kuyeng, Karim; Mclnerney, J. M.Sudden enhancement in high-frequency absorption is a well-known impact of solar flare-driven Short-Wave Fadeout (SWF). Less understood, is a perturbation of the radio wave frequency as it traverses the ionosphere in the early stages of SWF, also known as the Doppler flash. Investigations have suggested two possible sources that might contribute to it’s manifestation: first, enhancements of plasma density in the D-and lower E-regions; second, the lowering of the F-region reflection point. Our recent work investigated a solar flare event using first principles modeling and Super Dual Auroral Radar Network (SuperDARN) HF radar observations and found that change in the F-region refractive index is the primary driver of the Doppler flash. This study analyzes multiple solar flare events observed across different SuperDARN HF radars to determine how flare characteristics, properties of the traveling radio wave, and geophysical conditions impact the Doppler flash. In addition, we use incoherent scatter radar data and first-principles modeling to investigate physical mechanisms that drive the lowering of the F-region reflection points. We found, (a) on average, the change in E- and F-region refractive index is the primary driver of the Doppler flash, (b) solar zenith angle, ray’s elevation angle, operating frequency, and location of the solar flare on the solar disk can alter the ionospheric regions of maximum contribution to the Doppler flash, (c) increased ionospheric Hall and Pedersen conductance causes a reduction of the daytime eastward electric field, and consequently reduces the vertical ion-drift in the lower and middle latitude ionosphere, which results in lowering of the F-region ray reflection point.Item Restricted Prompt penetration and substorm effects over Jicamarca during the September 2017 geomagnetic storm(American Geophysical Union, 2021-08) Fejer, B. G.; Navarro, L. A.; Sazykin, S.; Newheart, A.; Milla, Marco; Condor, PercyWe used reanalyzed Jicamarca radar measurements to study the response of equatorial ionospheric electrodynamics and spread F during the main phase of the large September 2017 geomagnetic storm. Our observations near dusk on 7 September show very large upward drifts followed by a large short-lived downward drift perturbation that completely suppressed the lower F region plasma irregularities and severely decreased the backscattered power from the higher altitude spread F. We suggest that this large short-lived westward electric field perturbation is most likely of magnetospheric origin and is due to a sudden and very strong magnetic field reconfiguration. Later in the early night period, data indicate large, mostly upward, drift perturbations generally consistent with standard undershielding and overshielding electric field effects, but with amplitudes significantly larger than expected. Our analysis suggests that occurrence of storm-time substorms is one of the major factors causing the large nighttime westward and eastward electric field perturbations observed at Jicamarca near the storm main phase. Our analysis also suggests that magnetospheric substorms play far more important roles on the electrodynamics of the equatorial nighttime ionosphere than has generally been thought.Item Restricted The CosmoAmautas project for equitable scientific education in Peru(Nature Research, 2022-02-18) Calistro Rivera, Gabriela; Bardalez Gagliuf, Daniella; Alvarado Urrunaga, Diego; Gonzales Quevedo, Lisseth; Klefman, Daniel; Meza, Erick; Quispe Quispe, Adita; Ramos Lázaro, Jenny Margot; Ricra, José; Rodríguez Marquina, Bruno; Torre Ramirez, ErikaWe all live under the same sky. This accessibility places astronomy in a unique position to inspire awe and connect people from a variety of backgrounds. Astronomy thus has the potential to promote equity and diversity in society, while providing the technical basis for the inclusion of the scientific method in education. Peru is a country with an astronomical tradition that goes back millennia to the most ancient cultures in the Americas. This heritage, in conjunction with the under-exploited world-class quality of the Peruvian skies, makes astronomy a highly applicable tool for scientific and socioeconomic development, as defined by the United Nations Sustainable Development Goals. Such a contribution is timely and urgent as countries in Latin America are experiencing the worst educational crisis in their history due to the COVID-19 pandemic. The case of Peru has been particularly critical, with more than 85% of schools closed throughout 2020 and 2021, and the public education system in a declared state of emergency until 2022. Even before the pandemic, Peru had one of the lowest scores in Latin America in the areas of science and maths based on Programme for International Student Assessment (PISA) evaluations. In particular, the most striking gaps are found between rural and urban female students as evidenced by an illiteracy rate of 21.2% for the female rural population over 15 years old compared with the average national illiteracy rate of 5.5% (ref.), reflecting severe inequalities in education.Item Restricted Mapping irregularities in the postsunset equatorial ionosphere with an expanded network of HF beacons(American Geophysical Union, 2021-07) Hysell, D. L.; Rojas, E.; Goldberg, H.; Milla, Marco; Kuyeng, K.; Valdez, A.; Morton, Y. T.; Bourne, H.Data from a network of high-frequency (HF) beacons deployed in Peru are used to estimate the regional ionospheric electron density in a volume. Pseudorange, accumulated carrier phase, and signal power measurements for each of the 36 ray paths provided by the network at a 1 min cadence are incorporated in the estimates. Additional data from the Jicamarca incoherent scatter radar, the Jicamarca sounder, and GPS receivers can also be incorporated. The electron density model is estimated as the solution to a global optimization problem that uses ray tracing in the forward model. The electron density is parametrized in terms of B-splines in the horizontal direction and generalized Chapman functions or related functions in the vertical. Variational sensitivity analysis has been added to the method to allow for the utilization of the signal power observable which gives additional information about the morphology of the bottomside F region as well as absorption including absorption in the D and E regions. The goal of the effort is to provide contextual information for improving numerical forecasts of plasma interchange instabilities in the postsunset F region ionosphere associated with equatorial spread F (ESF). Data from two ESF campaigns are presented. In one experiment, the HF data revealed the presence of a large-scale bottomside deformation that seems to have led to instability under otherwise inauspicious conditions. In another experiment, gradual variations in HF signal power were found to be related to the varying shape of the bottomside F layer.Item Restricted Ionospheric echo detection in digital ionograms using convolutional neural networks(American Geophysical Union, 2021-08) De la Jara, César; Olivares, C.An ionogram is a graph of the time that a vertically transmitted wave takes to return to the earth as a function of frequency. Time is typically represented as virtual height, which is the time divided by the speed of light. The ionogram is shaped by making a trace of this height against the frequency of the transmitted wave. Along with the echoes of the ionosphere, ionograms usually contain a large amount of noise and interference of different nature that must be removed in order to extract useful information. In the present work, we propose a method based on convolutional neural networks to extract ionospheric echoes from digital ionograms. Extraction using the CNN model is compared with extraction using machine learning techniques. From the extracted traces, ionospheric parameters can be determined and electron density profile can be derived.Item Restricted Spectral Analysis of Incoherent Scatter Radar Signals in Faraday/Double Pulse Experiments at the Jicamarca Radio Observatory(IEEE, Institute of Electrical and Electronics Engineers, 2021) Flores, Roberto; Milla, Marco; Kuyeng, KarimThe Jicamarca incoherent scatter radar can be operated in different modes to measure the main physical parameters of the equatorial ionosphere. One of these modes is the Faraday/Double Pulse experiment that was designed to estimate F -region plasma densities and electron/ion temperatures by pointing the Jicamarca antenna beam off-perpendicular to the geomagnetic field. For several years, the data processing for this mode was performed in time domain (correlation analysis), but sometimes the data is contaminated with frequency interference and other unwanted signals that are not easy to remove. To obtain better results, a spectral analysis procedure for this mode has been implemented in Signal Chain, a python-based radar signal processing library developed at the Jicamarca Radio Observatory. Signal Chain includes algorithms for interference and clutter removal to clean the spectral data before estimating the geophysical parameters. The procedure applies an outlier removal algorithm before calculating incoherently averaged power spectra. This algorithm, based on the Hildebrand-Sekhon method, is applied to sequences of spectral data for each frequency bin. Then, the DC clutter from the self- and cross-spectra is removed as a second step in the cleaning process. In this work, we present the results obtained with the spectral analysis procedure applied to the the FaradaylDouble Pulse experiment and compared the electron densities estimated with this method with the ones obtained with the standard correlation analysis.Item Restricted SOPHy: Scanning-system for Observations of Peruvian Hydrometeorological-events(IEEE, Institute of Electrical and Electronics Engineers, 2021) Espinoza, Juan C.; Scipión, Danny; Valdez, Alexander; Verástegui, JoaquínIn this paper we present the current progress in the construction of the first X-band dual-pol mobile weather radar (SOPHy) in Peru. This portable mobile system allows scans in azimuth and elevation with a maximum range of 60 km. The radar transmission and reception systems are based on SDR (Software Defined Radio) technologies for configuration flexibility. The objective of the radar is to study precipitation in an area of several tens of kilometers around the radar, in order to research the climate and atmospheric conditions in Peru.