Browsing by Author "Sojka, Jan J."

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    Lunar atmospheric tidal effects in the plasma drifts observed by the Low‐Latitude Ionospheric Sensor Network
    (American Geophysical Union, 2011-07-21) Eccles, Vince; Rice, Donald D.; Sojka, Jan J.; Valladares, Cesar E.; Bullet, Terence; Chau Chong Shing, Jorge Luis
    Data from the Low‐Latitude Ionospheric Sensor Network are used to examine ionospheric electrodynamics during quiet, low solar conditions from September to November 2009. The ground‐based magnetometers and the Jicamarca Vertical Incidence Pulsed Ionospheric Radar ionosonde in the Peruvian Sector are used to identify the neutral winds and plasma drifts that control the large‐scale plasma structure of the ionosphere. It is observed that the solar‐ and lunar‐driven semidiurnal tides have a significant influence on the background electrodynamics during this period of extreme solar minimum. The lunar tidal influence of the ionosphere electrodynamics is a large component of the variation of the vertical drift during the geophysically quiet study period. A significant portion, though not all, of the variation through the lunar month can be attributed to the lunar semidiurnal tide.
    Palabras clave:Electric fieldsEquatorialIonosphere
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    Mid-latitude plasma and electric field measurements during space weather month, September 1999
    (Elsevier, 2003-07) Makela, Jonathan J.; Kelley, Michael C.; González, Sixto A.; Aponte, Nestor; Sojka, Jan J.
    Using data collected during the September 1999 combined ionospheric campaign (CIC), we examine the effects of moderate geomagnetic activity on low and mid-latitudes. Perturbations in the zonal electric field, measured at both Jicamarca and Arecibo, are the most striking aspect of this data. These eastward electric fields resulted in a poleward advection of the Appleton anomaly to mid-latitudes, where it was observed as a gradient in the nighttime electron density, as measured by the Arecibo incoherent scatter radar. This gradient was severe enough that it was observable in airglow measurements at 630.0 and . To put this data into context, we also examine the worldwide conditions during this time period and find evidence for several substorms, penetrating electric fields, and disturbance dynamo electric fields.
    Palabras clave:Mid-latitude density gradientsElectric field perturbationsMid-latitude ionosphere