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Item type:Publication, Short-term prediction of horizontal winds in the mesosphere and lower thermosphere over coastal Peru using a hybrid model(Frontiers Media SA, 2024-01-01)The mesosphere and lower thermosphere (MLT) are transitional regions between the lower and upper atmosphere. The MLT dynamics can be investigated using wind measurements conducted with meteor radars. Predicting MLT winds could help forecast ionospheric parameters, which has many implications for global communications and geo-location applications. Several literature sources have developed and compared predictive models for wind speed estimation. However, in recent years, hybrid models have been developed that significantly improve the accuracy of the estimates. These integrate time series decomposition and machine learning techniques to achieve more accurate short-term predictions. This research evaluates a hybrid model that is capable of making a short-term prediction of the horizontal winds between 80 and 95 km altitudes on the coast of Peru at two locations: Lima (12°S, 77°W) and Piura (5°S, 80°W). The model takes a window of 56 data points as input (corresponding to 7 days) and predicts 16 data points as output (corresponding to 2 days). First, the missing data problem was analyzed using the Expectation Maximization algorithm (EM). Then, variational mode decomposition (VMD) separates the components that dominate the winds. Each resulting component is processed separately in a Long short-term memory (LSTM) neural network whose hyperparameters were optimized using the Optuna tool. Then, the final prediction is the sum of the predicted components. The efficiency of the hybrid model is evaluated at different altitudes using the root mean square error (RMSE) and Spearman’s correlation (r). The hybrid model performed better compared to two other models: the persistence model and the dominant harmonics model. The RMSE ranged from 10.79 to 27.04 (Formula presented.), and the correlation ranged from 0.55 to 0.94. In addition, it is observed that the prediction quality decreases as the prediction time increases. The RMSE at the first step reached 6.04 (Formula presented.) with a correlation of 0.99, while at the sixteenth step, the RMSE increased up to 30.84 (Formula presented.) with a correlation of 0.5. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, 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 Ltd, 2024-10-01)Coherent 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 (≳ 10%) 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. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, The impact of the Hunga Tonga–Hunga Ha’apai volcanic eruption on the Peruvian atmosphere: From the sea surface to the ionosphere(Springer Science and Business Media Deutschland GmbH, 2024-12-01)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. Graphical (Figure presented.) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, On New Two-Dimensional UHF Radar Observations of Equatorial Spread F at the Jicamarca Radio Observatory(Springer Science and Business Media Deutschland GmbH, 2023-12-01)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. Graphical abstract: [Figure not available: see fulltext.]. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Monitoring the Equatorial Ionosphere With the Upgraded Unattended Mode at Jicamarca(Wiley, 2026-04-01)For several years, the Geophysical Institute of Peru (IGP) has monitored the equatorial ionosphere using its main ionospheric radar located at the Jicamarca Radio Observatory. The radar operated in two standard modes: the Incoherent Scatter Radar (ISR) mode, which employs up to 4 High Power Large‐Aperture amplifiers with a peak power of 1 MW each and 5% duty cycle, to measure plasma drifts, electron and ion temperatures, and composition, typically operating about 1,000 hr per year; and the Jicamarca Unattended Long‐term investigations of the Ionosphere and Atmosphere (JULIA) mode, which used low‐power amplifiers (∼20 kW) to study equatorial ionospheric irregularities such as the Equatorial Electrojet, the Equatorial Spread‐F, and the 150‐km echoes, operating approximately 4,000 hr per year. In 2022, two solid‐state transmitters, each with a peak power of 96 kW and duty cycle of 10% were installed to enable unattended ISR measurements, making it possible to combine certain features of the ISR mode and JULIA mode, such as vertical and zonal plasma drifts up to 500 km and the measurements of coherent equatorial echoes like Equatorial Electrojet, 150‐km echoes and Equatorial Spread‐F. With this new JULIA ‐ Medium Power (JULIA‐MP) mode, the observations of equatorial ionospheric parameters have increased to approximately 5,000 hr per year. This paper presents the new JULIA‐MP mode, outlining the experimental setup and summarizing the data statistics registered during 2024.1