Browsing by Author "Condori, L."
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Item Open Access Data-driven numerical simulations of equatorial spread F in the Peruvian sector 3: Solstice(American Geophysical Union, 2015-11-19) Hysell, D. L.; Milla, Marco; Condori, L.; Vierinen, J.We present results from a continuing effort to simulate equatorial spread F (ESF) using observations from the Jicamarca Radio Observatory near Lima, Peru. Jicamarca measures vertical and zonal plasma drifts along with plasma number density profiles overhead. The number density profiles are used to initialize a three-dimensional regional model of the ionosphere capable of simulating plasma density irregularities produced during ESF conditions. The vertical drifts measurements are used to drive the numerical simulation continuously. Neutral winds are derived from the new Horizontal Wind Model '14 (HWM-14) model, and the zonal winds are scaled so as to make the zonal plasma flows at the start of the simulation agree with the ISR profile measurements. Coherent scatter radar imagery from Jicamarca is used to validate the simulation results. Campaign data were collected in April and December, 2014, and a few events representative of low and high ESF activity were selected for analysis. The numerical simulations are able to reproduce the level of activity observed along with the gross features of the ESF irregularities and radar plumes. Data from a network of HF beacons are being incorporated into the forecast analysis in order to elucidate radar plumes which sometimes appear even when the simulation fails to predict them.Item Open Access Data‐driven numerical simulations of equatorial spread F in the Peruvian sector: 2. Autumnal equinox(American Geophysical Union, 2014-08-11) Hysell, D. L.; Milla, Marco; Condori, L.; Meriwether, J. W.An ongoing effort to simulate plasma instability in the equatorial ionosphere leading to equatorial spread F (ESF) in the American sector is described. Ionospheric state parameters including plasma number density and vector drift velocity profiles were measured at the Jicamarca Radio Observatory in the period between 20 September and 3 October 2013. Coherent radar backscatter from plasma irregularities was recorded simultaneously, and images of the irregularities were calculated using aperture synthesis methods. Neutral winds were measured by the red line Fabry‐Perot interferometers at Jicamarca and Arequipa, Peru. A fully 3‐D numerical simulation of ionospheric irregularities, initialized and forced using parameterizations derived from measurements and empirical models, was used to reproduce the ESF activity observed. Simulations were able to recover many of the features of the irregularities, although some important anomalies can be noted. ESF events in which the first appearance of radar plumes occurred either very early or very late were not reproduced in simulation and may be indicative of nonlocal influence.Item Open Access Lifetime of a depression in the plasma density over Jicamarca produced by space shuttle exhaust in the ionosphere(American Geophysical Union, 2001-09-01) Bernhardt, P. A.; Huba, J. D.; Kudeki, E.; Woodman Pollitt, Ronald Francisco; Condori, L.; Villanueva, F.When the space shuttle orbiting maneuver subsystem (OMS) engines burn in the ionosphere, a plasma density depression, or “hole,” is produced. Charge exchange between the exhaust molecules and the ambient O+ ions yields molecular ion beams that eventually recombine with electrons. The resulting plasma hole in the ionosphere can be studied with ground‐based, incoherent scatter radars (ISRs). This type of ionospheric modification is being studied during the Shuttle Ionospheric Modification with Pulsed Localized Exhaust (SIMPLEX) series of experiments over ISR systems located around the globe. The SIMPLEX 1 experiment occurred over Jicamarca, Peru, in the afternoon on October 4, 1997, during shuttle mission STS 86. An electron density depression was produced at 359 km altitude at the midpoint of a magnetic field line. The experiment was scheduled when there were no zonal drifts of the plasma so the modified field line remained fixed over the 50 MHz Jicamarca radar. The density depression was filled in by plasma flowing along the magnetic field line with a time constant of 4.5 min. The density perturbation had completely vanished 20 min after the engine burn. The experimental measurements were compared with two models: (1) SAMI2, a fully numerical model of the F region, and (2) an analytic representation of field‐aligned transport by ambipolar diffusion. The computed recovery time from each model is much longer than the observed recovery time. The theory of ambipolar diffusion currently used in ionospheric models seems to be inadequate to describe the SIMPLEX 1 observations. Several possible sources for this discrepancy are discussed. The SIMPLEX 1 active experiment is shown to have the potential for testing selected processes in ionospheric models.Item Open Access Modos de observación en el espacio cercano con el radar de Jicamarca(Instituto Geofísico del Perú, 2010) Kuyeng, K.; Castillo, O.; Condori, L.; Chau Chong Shing, Jorge LuisEl Radio Observatorio de Jicamarca (ROJ) es la principal estación ecuatorial de la cadena de radio observatorios de dispersión incoherente (cuyas siglas en inglés es ISR) del hemisferio oeste que se extienden desde Lima - Perú hasta Søndre Strømfjord, Groelandia y la más importante en el mundo para estudiar la ionósfera ecuatorial. Esta compuesto de tres transmisores de 1.5 MW y un arreglo de antenas de 18,432 dipolos, cubriendo un área aproximada de 85,000 m2. El estudio de la ionósfera ecuatorial ha adquirido mayor importancia debido, en gran parte,a las contribuciones hechas por el Radio Observatorio de Jicamarca. El Observatorio se ubica a media hora de viaje en automóvil hacía el este de Lima y a 10 kms de la Carretera Central (latitud 11.95°Sur, longitud 76.87° Oeste).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.