Browsing by Author "Milla, M."
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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 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 Open Access Estimation of spectral parameters from oblique Equatorial Electrojet echoes using a double skewed Gaussian model at JRO(2023 CEDAR Workshop, 2023) Flores, Roberto; Milla, M.; Kuyeng, Karim; Hysell, D.L.; Chau, J.L.Coherent echoes from the equatorial electrojet (EEJ) region are detected at the Jicamarca Radio Observatory (JRO) by using an array of 16 Yagi antennas with a main beam pointed obliquely to the west with an elevation of about 35 deg. The spectrum of these observations are composed of two types of EEJ echoes (Type I and Type II)[1] from which we can estimate their main spectral parameters such as Doppler shift and spectral width independently for each type. Previously, the method applied to obtain these parameters was a standard fitting approach based on a double Gaussian model. However, in some cases, the shape of the spectral measurements are not symmetric (resembling the shape of a skewed distribution). Based on simulations, we determined that the skewed shape of the oblique EEJ spectrum comes from the fact that the measured spectrum is the result of the sum of spectral contributions coming from different heights, with different Doppler shifts and spectral widths weighted by the antenna beam shape. The overall result is an asymmetric spectrum with a peak that does not coincide with the average Doppler shift. Thus in order to account for this effect, we have implemented a double skewed Gaussian distribution model to fit the oblique EEJ measurements and estimate their spectral parameters. In this work, we present the results obtained in the simulation showing the skewed shape of the spectrum. Based on our simulations, we have also proved that the shift of the skewed Gaussian model can be interpreted as the Doppler shift of the echoes. In addition, some examples of the new fitting procedure are shown in comparison with the classical Gaussian fitting where it can be seen the better agreement between the data and the double skewed Gaussian model.Item Open Access Implementation of an Ionospheric Echoes Receiver using an SDR with GNU Radio to obtain vertical and oblique ionograms(2023 CEDAR Workshop, 2023-06) Tupac, Isaac; Milla, M.; Valladares, C.E.; Espinoza, J.C.; De la Jara, César; Arboleda, E.; Belleza, A.; Vila, N.; Scipión, DannyThe Jicamarca Radio Observatory (JRO) operates a vertical incidence pulsed ionospheric radar (VIPIR) dedicated to probing the equatorial ionosphere. This high-resolution system runs 24/7 and complements the suite of observations performed at JRO. As the VIPIR ionosonde operates with a wide beam antenna and reflected signals are dispersed at distances far as 1500 km, we have designed, built, and installed four new VIPIR receivers dedicated to oblique sounding. These receivers increase and expand the system's field of view and enable unique measurements, yielding new scientific results. This poster describes the Ionospheric Echoes Receiver (IER) by listing its components and detailing the different parts of the hardware and software elements. The receivers use a USRP N200 by Ettus and an acquisition flowgraph implemented in GNU Radio Companion. In addition, we present the OOT (Out Of Tree block), which generates the demodulation signal and changes its frequency value each Inter Pulsed Period. We also show preliminary displays of the vertical and oblique ionograms acquired using the Jicamarca VIPIR and the new receivers.Item Open Access Long term analysis of high-resolution E-region neutral wind estimations over Jicamarca: First results(2024 CEDAR Workshop, 2024-06) Flores, Roberto; Milla, M.; Hysell, D. L.Ground based techniques can be used to measure neutral zonal winds, such as the ISR technique which is usually performed to estimate zonal wind profiles from measured ion drifts at mid- and high-latitude but cannot be used at low-latitudes due to clutter from coherent echoes at E-layer (EEJ). Additionally, the Spread Spectrum Interferometric Multistatic meteor radar Observing Network (SIMONe) system, deployed in September 2019, can estimate neutral winds from specular meteor trail echoes in the mesosphere and lower thermosphere (MLT) region (70 - 110 km) which includes the EEJ layer, however the time resolution is 1 hour and it probes a larger volume than our oblique radar, then estimated winds will be a result of a contribution from different regions. Space-based missions have also been used to measure these winds such as the Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) on board the ICON satellite, the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) among others, but their measurements are not continuous over a specific latitude and longitude as they orbit around the planet. On the other hand, a technique to estimate zonal neutral winds from oblique EEJ type II Doppler shifts, sampled every minute approximately, was proposed by Shume et al. [2005]. This method predicts Doppler shifts from neutral winds, compares the Doppler with the measured ones and updates the winds until the best data-model agreement of the Doppler shift (RMSE≤2.0). Although wind estimations are limited to the EEJ echoes detection and SNR intensity, this method provides high time resolution wind profiles from 97 to 107 km approximately and might be complemented by other techniques. This work presents the first results of neutral wind estimations over the Jicamarca Radio Observatory (JRO), a facility of Instituto Geofísico del Perú (IGP), at the EEJ region with a resolution of 5 minutes and 700 meters using oblique spectra data fitted by a skewed Gaussian distribution.Item Open Access Preliminary AMISR-14 radar observations of F-region incoherent backscatter echoes at the Jicamarca Radio Observatory (JRO)(2022 CEDAR Workshop, 2022-06) Apaza, Joab; Kuyeng, Karim; Flores, Roberto; Milla, M.; Rodrigues, F. S.; Scipión, DannyA 14-panel Advanced Modular Incoherent Scatter Radar (AMISR-14) was installed at the Jicamarca Radio Observatory (IGP- JRO) in 2014. Because of its size, this radar was mainly used to observe coherent echoes such as those produced by the Equatorial Electrojet (EEJ) and Equatorial Spread F (ESF). However, the radar operation was intermittent until 2019 when repairs started to make the radar fully operational. Now, AMISR-14 runs regularly in parallel with the main Jicamarca radar in the JULIA (Jicamarca Unattended Long-term studies of the Ionosphere and Atmosphere) mode to monitor the Equatorial Spread F activity. More recently, we found that running these experiments with a more stable peak power, we have been able to detect not only coherently scatter (CS) signals but also what seems to be incoherently scattered (IS) echoes from the F-region ionosphere. In this poster, we will present some examples of the experiments we have been conducting with AMISR-14. More specifically, we will present and discuss examples of these interesting ISR-like echoes observed with AMISR-14 pointing in different directions along the E-W plane.Item Open Access Preliminary results of new operation mode JULIA Medium Power at JRO(2023 CEDAR Workshop, 2023-06) Kuyeng, Karim; Scipión, Danny; Condor, P.; Manay, E.; Milla, M.The main radar of the Jicamarca Radio Observatory (JRO), for several years, has operated with two main modes, the ISR mode with big transmitters (1.5 MW), operating around 1000 hours per year, to survey the ionosphere and obtain parameters such as drifts, densities and composition; and the JULIA mode with low power transmitters (20 kW), operating around 4000 hours per year, to measure mostly coherent echoes such as Equatorial Electrojet, Spread F and 150 km echoes to provide with a proxy of the behavior of the ionosphere. Starting in 2022, two new solid-state transmitters were installed at JRO, with peak power of 96 kW each, making it possible to not only detect coherent echoes but to be able to estimate zonal and vertical drifts in the ionosphere too. This new mode, called JULIA Medium Power (JULIA MP), is capable of measuring the same coherent echoes as the original JULIA but able to estimate zonal and vertical drifts up to 500 km. This work will present the preliminary results of this mode, comparisons of the coherent echoes obtained with JULIA and JULIA MP and finally show the quality of drifts we are getting with this medium power mode.Item Open Access Quality improvements to the spectral data acquired from HF multi-static sounding system at the magnetic Equator(2023 SWOL Workshop, 2023-10) Vásquez, V.; Milla, M.; Kuyeng, Karim; Gonzales, J.; Scipión, DannyA network of HF radio beacons and receivers for ionospheric sounding 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. The HF radar used only one frequency for transmission and reception that generated interference between different transmitter stations in the analyzed spectrum. To improve the quality of the spectral data, changes were made to the operation of the radar. Spectral separation of the transmitted signals was carried out, followed by the implementation of an algorithm that extracts only the signals of interest from the measured spectrum, discarding the noisy areas. The procedure for the changes made to the HF system, along with comparisons of the final data, is shown in this work.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.