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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Bottom side profiles for two close stations at the southern crest of the EIA: Differences and comparison with IRI-2012 and NeQuick2 for low and high solar activity

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Author(s):
Perna, L. [1, 2] ; Venkatesh, K. [3] ; Pillat, V. G. ; Pezzopane, M. [1] ; Fagundes, P. R. [3] ; Ezquer, R. G. [4, 5, 6] ; Cabrera, M. A. [5, 7]
Total Authors: 7
Affiliation:
[1] Ist Nazl Geofis & Vulcanol, Via Vigna Murata 605, I-00143 Rome - Italy
[2] Univ Bologna Alma Mater Studiorum, Viale Berti Pichat 6-2, I-40126 Bologna - Italy
[3] Univ Vale Paraiba UNIVAP, IP&D, Sao Jose Dos Campos, SP - Brazil
[4] Consejo Nacl Invest Cient & Tecn, Buenos Aires, DF - Argentina
[5] Univ Tecnol Nacl, Fac Reg Tucumcin, CIASUR, Buenos Aires, DF - Argentina
[6] Univ Nacl Tucuman, Lab Ionosfera, San Miguel De Tucuman, Tucuman - Argentina
[7] Univ Nacl Tucuman, Lab Telecomunicac, San Miguel De Tucuman, Tucuman - Argentina
Total Affiliations: 7
Document type: Journal article
Source: Advances in Space Research; v. 61, n. 1, p. 295-315, JAN 1 2018.
Web of Science Citations: 1
Abstract

Bottom side electron density profiles for two stations at the southern crest of the Equatorial Ionization Anomaly (EIA), Sao Jose dos Campos (23.1 degrees S, 314.5 degrees E, dip latitude 19.8 degrees S; Brazil) and Tucuman (26.9 degrees S, 294.6 degrees E, dip latitude 14.0 degrees S; Argentina), located at similar latitude and separated by only 20 in longitude, have been compared during equinoctial, winter and summer months under low (year 2008, minimum of the solar cycle 23/24) and high solar activity (years 2013-2014, maximum of the solar cycle 24) conditions. An analysis of parameters describing the bottom side part of the electron density profile, namely the peak electron density NmF2, the height hmF2 at which it is reached, the thickness parameter B-0 and the shape parameter B-1, is carried out. Further, a comparison of bottom side profiles and F-layer parameters with the corresponding outputs of IRI-2012 and NeQuick2 models is also reported. The variations of NmF2 at both stations reveal the absence of semi-annual anomaly for low solar activity (LSA), evidencing the anomalous activity of the last solar minimum, while those related to hmF2 show an uplift of the ionosphere for high solar activity (HSA). As expected, the EIA is particularly visible at both stations during equinox for HSA, when its strength is at maximum in the South American sector. Despite the similar latitude of the two stations upon the southern crest of the ETA, the anomaly effect is more pronounced at Tucuman than at Sao Jose dos Campos. The differences encountered between these very close stations suggest that in this sector relevant longitudinal-dependent variations could occur, with the longitudinal gradient of the Equatorial Electrojet that plays a key role to explain such differences together with the 5.8 degrees separation in dip latitude between the two ionosondes. Furthermore at Tucuman, the daily peak value of NmF2 around 21:00 LT during equinox for HSA is in temporal coincidence with an impulsive enhancement of hmF2, showing a kind of ``elastic rebound{''} under the action of the EIA. TRI-2012 and NeQuick2 bottom side profiles show significant deviations from ionosonde observations. In particular, both models provide a clear underestimation of the ETA strength at both stations, with more pronounced differences for Tucuman. Large discrepancies are obtained for the parameter hmF2 for HSA during daytime at Sao Jose dos Campos, where clear underestimations made by both models are observed. The shape parameter B-0 is quite well described by the IRI-2012 model, with very good agreement in particular during equinox for both stations for both LSA and HSA. On the contrary, the two models show poor agreements with ionosonde data concerning the shape parameter B-1. (C) 2017 COSPAR. Published by Elsevier Ltd. All rights reserved. (AU)

FAPESP's process: 12/08445-9 - Study of day-to-day variability of the mesosphere, thermosphere and ionosphere at low latitude and equatorial region, during the solar cycle 24
Grantee:Paulo Roberto Fagundes
Support type: Research Projects - Thematic Grants