Browsing by Author "Condor, Percy"

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    Automatic identification and observations of blanketing sporadic E events in the equatorial region over Jicamarca
    (Institute of Electrical and Electronics Engineers, IEEE, 2020-10-20) Suclupe, José; Pacheco, Edgardo E.; Condor, Percy
    In equatorial regions, equatorial electrojet (EEJ) echoes often overlap with blanketing sporadic E (Esb) echoes. Also, Esb events could be classified as rare events over the Jicamarca Radio Observatory (JRO). For that reason, Esb identification is a big challenge for current software. Until now, the conventional method identifies Esb echoes visually. In this work, an innovative approach for automatic identification and observation of Esb events is presented. We developed an algorithm and implemented the first software to identify Esb events using image processing techniques and machine learning algorithms getting a sensitivity of 89%. We proposed a new criterion to identify Esb events taken into account the normal tendency of the F-layer minimum frequency due mainly to absorbance of the D region. We report the results of the first statistical study of Esb occurrence over JRO (11.95° S, 76.87° W and dip angle ~1°) using the Digital Portable Sounder (DPS) - 4 Digisonde data from 2001 to 2018. We found Esb occurs mainly during the December solstice and also during minimum solar years. We observe the occurrence of Esb with a main peak at 1600 LT and a second peak around 0800 - 0900 LT. Furthermore, we obtained the ΔH between Jicamarca and Piura to measure the intensity of EEJ and counter electrojet (CEJ) and its behavior in time when Esb occurs. Finally, we discuss possible conditions that favor the formation of Esb.
    Palabras clave:Blanketing sporadic EIonogramsMachine learning algorithms
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    On the mutual relationship of the equatorial electrojet, TEC and scintillation in the Peruvian sector
    (American Geophysical Union, 2016-05-31) Khadka, Sovit M.; Valladares, Cesar; Pradipta, Rezy; Pacheco, Edgardo E.; Condor, Percy
    This paper presents the interrelationship between the equatorial electrojet (EEJ) strength, Global Positioning System (GPS)‐derived total electron content (TEC), and postsunset scintillation from ground observations with the aim of finding reliable precursors of the occurrence of ionospheric irregularities. Mutual relationship studies provide a possible route to predict the occurrence of TEC fluctuation and scintillation in the ionosphere during the late afternoon and night respectively based on daytime measurement of the equatorial ionosphere. Data from ground based observations in the low latitudes of the west American longitude sector were examined during the 2008 solar minimum. We find a strong relationship exists between the noontime equatorial electrojet and GPS‐derived TEC distributions during the afternoon mediated by vertical E × B drift via the fountain effect, but there is little or no relationship with postsunset ionospheric scintillation.
    Palabras clave:IonosphereEquatorial ElectrojetGlobal Positioning System
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    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, Percy
    We 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.
    Palabras clave:Magnetic stormsIonosphereF region