Browsing by Author "Kuyeng, K."
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Item Open Access First results of the refurbished SOUSY radar: Tropopause altitude climatology at 78°N, 16°E, 2008(American Geophysical Union, 2009-10) Hall, C. M.; Röttger, J.; Kuyeng, K.; Sigernes, F.; Claes, S.; Chau Chong Shing, Jorge LuisThe second generation SOUSY MST radar at 78°N, 16°E on Svalbard has recently completed its inaugural year of combined troposphere and mesosphere observations. Here, troposphere observations have been processed using a robust detection algorithm designed for obtaining tropopause climatology by automatic data processing, and the resulting monthly statistics have been compared with corresponding surface air temperatures. As our main objective, we describe the new radar system, present the tropopause detection method, and validate the results using radiosonde and surface temperature data. The tropopause height depends on the temperature of the underlying atmosphere but is also influenced by downward control from the stratosphere. We find that the climatological tropopause height is correlated with the surface temperature but with the former lagging the latter by approximately 1 month.Item Restricted High altitude echoes from the equatorial topside ionosphere during solar minimum(American Geophysical Union, 2021-02) Derghazarian, S.; Hysell, D. L.; Kuyeng, K.; Milla, MarcoWe describe a new class of nonthermal plasma density irregularities observed in the postmidnight topside equatorial ionosphere under low solar flux conditions. They are distinct from irregularities associated with equatorial spread F (ESF) in terms of their morphology and because they exhibit strong spectral sidebands at the lower-hybrid frequency. The coherent echoes were observed in a series high-altitude radar experiments performed at Jicamarca utilizing long- and coded double-pulse modes and a dual-beam mode. The coded double-pulse mode was used to measure the low-frequency characteristics of the echoes with fine range resolution. Doppler shifts of the main backscatter line were observed to fall between ±150 m/s. The long-pulse mode was employed for high-frequency spectral analysis which revealed the presence of strong spectral sidelobes at the lower-hybrid frequency. A dual-beam mode was used to investigate the horizontal structure of the echoes. Zonal drift speeds of 50–70 m/s were inferred with this mode, and longitudinal dimensions of approximately 270 km were estimated. The study summarizes with a discussion of different mechanisms that may be responsible for the phenomenon and the lower-hybrid sidebands in particular.Item Restricted Ionospheric Specification and Space Weather Forecasting With an HF Beacon Network in the Peruvian Sector(American Geophysical Union, 2018-08-14) Hysell, D. L.; Baumgarten, Y.; Milla, Marco; Valdez, A.; Kuyeng, K.A network of high‐frequency (HF) transmitters and receivers used for ionospheric specification is being installed in Peru. The HF transmitters employ multiple frequencies and binary phase coding with pseudorandom noise, and the observables provided by the receivers include group delay, Doppler shift, amplitude, bearing (from interferometry), and polarization. Statistical inverse methods are used to estimate F region density in a volume from the data regionally. The method incorporates raytracing based on the principles of Hamiltonian optics in the forward model and involves an ionospheric parametrization in terms of Chapman functions in the vertical and bicubic B‐spline interpolation in the horizontal. Regularization is employed to minimize the global curvature of the reconstructions. HF beacon data for two nights in January 2018 are presented. We use the reconstructions to investigate why plasma irregularities associated with equatorial spread F formed on one occasion and not the other. The data indicate that the background ionospheric flow is not simply frozen in, that is, that longitude and local time variations cannot be equated, even at regional scales. This has ramifications for equatorial spread F forecasting strategies that assume equivalence.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 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 Polar mesospheric summer echoes at 78°N, 16°E, 2008: First results of the refurbished sounding system (SOUSY) Svalbard radar(American Geophysical Union, 2009-06-06) Hall, C. M.; Röttger, J.; Kuyeng, K.; Tsutsumi, M.; Dyrland, M.; Chau Chong Shing, Jorge LuisThis paper examines in detail the electrical coupling between the high-, middle-, and low-latitude ionospheres during January 17–19, 1984, using interplanetary and high-latitude magnetic field data together with F region plasma drift measurements from the EISCAT, Sondre Stromfjord, Millstone Hill, Saint-Santin, Arecibo, and Jicamarca incoherent scatter radars. We study the penetration of both the zonal and meridional electric field components of high-latitude origin into the low-latitude and the equatorial ionospheres. In the dusk sector, a large perturbation of the zonal equatorial electric field was observed in the absence of similar changes at low and middle latitudes in the same longitudinal sector. The observations in the postmidnight sector are used to compare the longitudinal variation of the zonal perturbation electric field with predictions made from global convection models. Our results show that the meridional electric field perturbations are considerably more attenuated with decreasing latitude than the zonal fluctuations. As a result, we conclude that variations in the meridional electric field at low latitudes are largely due to dynamo effects. These observations are used to show that the global convection models reproduce a number of characteristics of low-latitude and equatorial electric fields associated with changes in the polar cap potential drop. In addition, we highlight several areas where there is still substantial disagreement between the electric field data and the theoretical results.Item Restricted Radio beacon and radar assessment and forecasting of equatorial F region ionospheric stability(American Geophysical Union, 2019-11) Hysell, D. L.; Milla, Marco; Kuyeng, K.Ionospheric conditions on two adjacent nights in March 2019 were observed at the Jicamarca Radio Observatory using a combination of incoherent scatter, coherent scatter, and high‐frequency (HF) radio modes. The HF data came from a network of beacons consisting of three transmitters and six receivers operating at two frequencies and deployed regionally. The HF beacons employ pseudorandom noise coding and can be used to measure group delay (pseudorange) and Doppler shift, and the time derivative of optical path length. A method for inferring volumetric estimates of electron density regionally from the HF data is described. The radar and HF data are interpreted in light of a direct numerical simulation of the ionospheric interchange instability to elucidate why convective plumes and equatorial spread F conditions occurred on one night but not the other. The numerical simulation accurately predicted whether convective plumes would develop on a given night, utilizing initial conditions and forcings derived from the incoherent scatter data. The HF data were consistent with the incoherent scatter observations and remained intelligible throughout the equatorial spread F event. Crests in the bottomside electron density associated with convective plumes at higher altitudes could be seen propagating through the region in the HF data. It should be possible to incorporate HF data in assimilative simulations of interchange instabilities in order to predict where and when individual convective plumes emerge.Item Open Access Rocket-borne radio beacon experiment for electron density measurements in the ionosphere(Instituto Geofísico del Perú, 2005) Sarango, M. F.; Woodman Pollitt, Ronald Francisco; Chau Chong Shing, Jorge Luis; Chocos, J. A.; De la Jara, César; Kuyeng, K.; Minchola, CarlosIn order to investigate the E and F-regions electrodynamics, a series of radar/rocket experiments were conducted in August-September, 2004, at Roi-Namur Is., Kwajalein Atoll (9.4° N, 167.5° E), as part of the NASA EQUIS II campaign. The ultimate object of these efforts was to improve the understanding of the electrodynamics associated with nighttime plasma density gradients near the magnetic equator. The rocket experiments consisted of instrumented payloads that included Langmuir probes and other instruments to measure de absolute plasma density. Separate rockets launched in conjunction with instrumented payloads released TMA trails in the upleg and downleg between roughly 90-250 Km that allowed observation of neutral winds and their velocity shears. These non-instrumented payloads also included a radio beacon experiment that provided an independent measurement of the plasma density and its variations...Item Open Access SIMONe Peru: deployment and operations(Instituto Geofísico del Perú, 2020-06) Suclupe, J.; Kuyeng, K.; Milla, Marco; Chau, J.L.; Urco, M.; Pfeffer, N.; Clahsen, M.; Vierinen, J.; Erickson, P.SIMONe Peru is a modern multistatic specular meteor radar which allows measuring winds in the mesosphere and lower thermosphere (MLT) between 70 and 110 km in altitude. Its main objective is to study the atmospheric dynamic in this region. Moreover, the system provides a higher number of detections compared to other systems and gives good statistics from detections in this region. This system started operations on september 2019 in the central coast of Peru. This work presents a general outline of the SIMONe Peru system, as well as the some preliminary results that allow us to operate and monitor it.Item Open Access Spectra analysis in Faraday/Double Pulse experiment at Jicamarca Radio Observatory (JRO)(Instituto Geofísico del Perú, 2021-06) Flores, R.; Milla, Marco; Kuyeng, K.At the Geophysical Institute of Peru, specifically on its Jicamarca Radio Observatory (JRO) facility, there are different operation modes to obtain the main parameters of the equatorial ionosphere. One of these modes is the Faraday/Double Pulse which estimates plasma densities and electron/ion temperatures at the F region by pointing the antenna beam off perpendicular to the magnetic field. The data processing for this mode is currently done by using voltage analysis, but in order to obtain better results, spectra analysis has been implemented by using the radar data processing library developed at JRO called Signal Chain. This tool can analyze samples with the same lag and it is also possible to remove the DC clutter from them. Another advantage is that before making the incoherent integration over the spectra, these data can be stored and the outliers from samples with the same frequency can be removed. Comparisons between the different processing programs are shown on this work.Item Open Access Tropopause altitude and PMSE detection at 78°N, 16°E, 2008: first results of the refurbished SOUSY Svalbard Radar (SSR2)(Instituto Geofísico del Perú, 2009) Hall, C. M.; Röttger, J.; Kuyeng, K.; Sigernes, F.; Claes, S.; Chau Chong Shing, Jorge LuisPresentado en MST12 - 12th Workshop on Technical and Scientific Aspects of MST Radars, London, Ontario, Canada, 17-23 May 2009.