Anomalous variations in the structure of the ionospheric F 2 region at geomagnetic midlatitudes of the Southern and Northern hemispheres in going from summer to winter conditions at high solar activity

Павлов, А. В.; Павлова, Н. М.; Makarenko, S. F.; Шубин, В.Н.

doi:10.1134/s001679320801009x

Cited by 16 publications

(4 citation statements)

References 14 publications

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“…This behaviour is found at LSA and HSA. The anomalous diurnal variation in f o F 2 was also reported by Sojka et al (1988) and Pavlov et al (2008) using data from the Argentine Islands ionosonde station (65.2 • S, 295.7…”

Section: Behaviour Of F O Fmentioning

confidence: 95%

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Variations of f o F 2 and GPS total electron content over the Antarctic sector

et al. 2011

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This paper presents a preliminary analysis of the variations of the critical frequency of the F 2 region ( f o F 2 ) and the total electron content (TEC) derived from Global Positioning System (GPS) data. Hourly f o F 2 values were scaled from ionograms recorded at San Martin (68.1• S, 293.0 • E) and the TEC values were derived from GPS observations at O Higgins (63.3• S, 302.5• E). The database includes measurements obtained under different seasonal and solar activity conditions. The study shows that the daily peak of f o F 2 occurs around local noon in winter and fall, and in spring a secondary peak is observed around midnight. In summer (January) f o F 2 reaches its minimum value around the noon sector while the maximum in the diurnal variation of f o F 2 is located in a time sector close to midnight. This behaviour is observed at low and high solar activity. The semiannual anomaly appears around noon at high and low solar activity and the winter anomaly is not observed. The effect of the solar activity is generally observed in every season. The analysis of the GPS TEC measurements in the same region indicates that the diurnal, seasonal and solar activity variations are similar to those observed in the f o F 2 values. An analysis of the performance of the IRI model to predict f o F 2 is also shown using the two IRI options (URSI and CCIR). The comparisons between the experimental values and the IRI predictions show some discrepancies.

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Section: Behaviour Of F O Fmentioning

confidence: 95%

“…Close to the midnight sector, the F 2 -layer is raised and maintained by plasma drift. As the ionosphere is sunlit during the long summer day in January N m F 2 increases producing the observed higher N m F 2 values close to midnight (Pavlov et al, 2008;Pavlov and Pavlova, 2009). …”

Section: Behaviour Of F O Fmentioning

confidence: 99%

Variations of f o F 2 and GPS total electron content over the Antarctic sector

et al. 2011

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“…Nighttime increases of the midlatitude F2 region electron density, Ne, (critical frequency, foF2, maximum electron density, NmF2, and total electron content, TEC) are wellknown phenomena (Evans, 1965;Da Rosa and Smith, 1967;Rao et al, 1982;Krinberg and Tashchilin, 1984;Bailey et al, 1991;Jakowski and Fö rster, 1995;Mikhailov and Fö rster, 1999;Mikhailov et al, 2000aMikhailov et al, , 2000bRichards et al, 2000;Belehaki and Tsagouri, 2002;Farelo et al, 2002;Dabas and Kersley, 2003;Pavlov and Pavlova, 2005;Luan et al, 2008;Pavlov et al, 2008;Yakovets et al, 2009). These phenomena are called also anomalous enhancements/increases of electron density, since the solar EUV radiation as the major source of ion production is absent during the nighttime.…”

Section: Introductionmentioning

confidence: 95%

Peculiarities of the nighttime winter foF2 increase over Irkutsk

Pirog

Dëminov

Deminova

et al. 2011

Advances in Space Research

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“…The morphology of the phenomenon, including the dependences of NmF2 enhancement parameters on the season, solar cycle phase, geomagnetic activity, and geographical location of monitoring stations was described in (Farelo et al, 2002;Mikhailov et al, 2000a,b). In (Bailey et al, 1991;Mikhailov et al, 2000a,b;Pavlov and Pavlova, 2005a,b;Pavlov et al, 2008), the mecha nisms of nighttime enhancements, including an upward plasma drift caused by meridional neutral wind at heights with small coefficients of recombination and amplification of the downward plasma flux from proto nosphere because of additional heating of the protono sphere plasma. The paper (Mikhailov et al, 2000a) refers to the difference between the mechanisms of formation enhancements NmF2 in summer and win ter, as well as in different phases of solar activity, so the study of frequency of formation (the probabilities of events) and other parameters of the enhancements on the season and solar activity is important for the iden tification of these mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Statistical features of NmF2 enhancements according to data from the Almaty station in solar cycles 23 and 24

et al. 2016

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According to frequent five minute vertical sounding of the ionosphere in Almaty (76°55′ E, 43°15′ N) conducted in 2000-2014, the rate of occurrence of nighttime enhancements of the electron concentration at the F2 layer maximum is analyzed, the distributions of enhancement durations are obtained, and the param eters of several very large enhancements recorded at the same time in Irkutsk and Almaty are compared. Dur ing the analyzed period, 2272 observation sessions were carried out. In 1430 sessions NmF2 enhancement was observed. The high probabilities of enhancement formation (up to 90%) in January, February, November and December are distribution features that are identical for high and low solar activity. In addition, a rapid decrease in the probability from February to March and smooth increase from September to December occurs in the same manner. High solar activity is characterized by a distinct maximum frequency in the sum mer months, whereas low activity is characterized by a minimum frequency. The seasonal dependence of dis tributions of enhancement durations is shown: durations are distributed over a wide range in the autumnwinter season and in a narrow range in the spring-summer season.

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Anomalous variations in the structure of the ionospheric F 2 region at geomagnetic midlatitudes of the Southern and Northern hemispheres in going from summer to winter conditions at high solar activity

Cited by 16 publications

References 14 publications

Variations of f o F 2 and GPS total electron content over the Antarctic sector

Variations of f o F 2 and GPS total electron content over the Antarctic sector

Peculiarities of the nighttime winter foF2 increase over Irkutsk

Statistical features of NmF2 enhancements according to data from the Almaty station in solar cycles 23 and 24

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