Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study
We present a statistical study of variations in the F2-layer peak electron density, <I>Nm</I>F2, and altitude, <I>hm</I>F2, over the Argentine Islands ionosonde. The critical frequencies, <I>fo</I>F2, and, <I>fo</I>E, of the F2 and E-layers, and the...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2009-04-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/27/1363/2009/angeo-27-1363-2009.pdf |
| _version_ | 1819038774741434368 |
|---|---|
| author | A. V. Pavlov N. M. Pavlova |
| author_facet | A. V. Pavlov N. M. Pavlova |
| author_sort | A. V. Pavlov |
| collection | DOAJ |
| description | We present a statistical study of variations in the
F2-layer peak electron density, <I>Nm</I>F2, and altitude, <I>hm</I>F2, over the Argentine
Islands ionosonde. The critical frequencies, <I>fo</I>F2, and, <I>fo</I>E, of the F2 and
E-layers, and the propagation factor, <I>M</I>(3000)F2, measured by the ionosonde during
the 1957–1959 and 1962–1995 time periods were used in the statistical
analysis to determine the values of <I>Nm</I>F2 and <I>hm</I>F2. The probabilities to observe
maximum and minimum values of <I>Nm</I>F2 and <I>hm</I>F2 in a diurnal variation of the
electron density are calculated. Our study shows that the main part of the
maximum diurnal values of <I>Nm</I>F2 is observed in a time sector close to midnight
in November, December, January, and February exhibiting the anomalous
diurnal variations of <I>Nm</I>F2. Another anomalous feature of the diurnal
variations of <I>Nm</I>F2 exhibited during November, December, and January when the
minimum diurnal value of <I>Nm</I>F2 is mainly located close to the noon sector.
These anomalous diurnal variations of <I>Nm</I>F2 are found to be during both
geomagnetically quiet and disturbed conditions. Anomalous features are not
found in the diurnal variations of <I>hm</I>F2. The statistical study of the <I>Nm</I>F2
winter anomaly phenomena over the Argentine Islands ionosonde was carried
out. The variations in a maximum daytime value, <I>R</I>, of a ratio of a
geomagnetically quiet daytime winter <I>Nm</I>F2 to a geomagnetically quiet daytime
summer <I>Nm</I>F2 taken at a given UT and for approximately the same level of
solar activity were studied. The conditional probability of the occurrence
of <I>R</I> in an interval of <I>R</I>, the most frequent value of <I>R</I>, the mean expected
value of <I>R</I>, and the conditional probability to observe the F2-region winter
anomaly during a daytime period were calculated for low, moderate, and high
solar activity. The calculations show that the mean expected value of <I>R</I> and
the occurrence frequency of the F2-region winter anomaly increase with
increasing solar activity. |
| first_indexed | 2024-12-21T08:42:40Z |
| format | Article |
| id | doaj.art-10c0853912e14d2eb5833658b94ac83b |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-21T08:42:40Z |
| publishDate | 2009-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-10c0853912e14d2eb5833658b94ac83b2022-12-21T19:09:55ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05762009-04-01271363137510.5194/angeo-27-1363-2009Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical studyA. V. Pavlov0N. M. Pavlova1Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio-Wave Propagation, Russian Academy of Science (IZMIRAN), Troitsk, Moscow Region, 142190, RussiaPushkov Institute of Terrestrial Magnetism, Ionosphere and Radio-Wave Propagation, Russian Academy of Science (IZMIRAN), Troitsk, Moscow Region, 142190, RussiaWe present a statistical study of variations in the F2-layer peak electron density, <I>Nm</I>F2, and altitude, <I>hm</I>F2, over the Argentine Islands ionosonde. The critical frequencies, <I>fo</I>F2, and, <I>fo</I>E, of the F2 and E-layers, and the propagation factor, <I>M</I>(3000)F2, measured by the ionosonde during the 1957–1959 and 1962–1995 time periods were used in the statistical analysis to determine the values of <I>Nm</I>F2 and <I>hm</I>F2. The probabilities to observe maximum and minimum values of <I>Nm</I>F2 and <I>hm</I>F2 in a diurnal variation of the electron density are calculated. Our study shows that the main part of the maximum diurnal values of <I>Nm</I>F2 is observed in a time sector close to midnight in November, December, January, and February exhibiting the anomalous diurnal variations of <I>Nm</I>F2. Another anomalous feature of the diurnal variations of <I>Nm</I>F2 exhibited during November, December, and January when the minimum diurnal value of <I>Nm</I>F2 is mainly located close to the noon sector. These anomalous diurnal variations of <I>Nm</I>F2 are found to be during both geomagnetically quiet and disturbed conditions. Anomalous features are not found in the diurnal variations of <I>hm</I>F2. The statistical study of the <I>Nm</I>F2 winter anomaly phenomena over the Argentine Islands ionosonde was carried out. The variations in a maximum daytime value, <I>R</I>, of a ratio of a geomagnetically quiet daytime winter <I>Nm</I>F2 to a geomagnetically quiet daytime summer <I>Nm</I>F2 taken at a given UT and for approximately the same level of solar activity were studied. The conditional probability of the occurrence of <I>R</I> in an interval of <I>R</I>, the most frequent value of <I>R</I>, the mean expected value of <I>R</I>, and the conditional probability to observe the F2-region winter anomaly during a daytime period were calculated for low, moderate, and high solar activity. The calculations show that the mean expected value of <I>R</I> and the occurrence frequency of the F2-region winter anomaly increase with increasing solar activity.https://www.ann-geophys.net/27/1363/2009/angeo-27-1363-2009.pdf |
| spellingShingle | A. V. Pavlov N. M. Pavlova Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study Annales Geophysicae |
| title | Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study |
| title_full | Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study |
| title_fullStr | Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study |
| title_full_unstemmed | Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study |
| title_short | Anomalous variations of <I>Nm</I>F2 over the Argentine Islands: a statistical study |
| title_sort | anomalous variations of i nm i f2 over the argentine islands a statistical study |
| url | https://www.ann-geophys.net/27/1363/2009/angeo-27-1363-2009.pdf |
| work_keys_str_mv | AT avpavlov anomalousvariationsofinmif2overtheargentineislandsastatisticalstudy AT nmpavlova anomalousvariationsofinmif2overtheargentineislandsastatisticalstudy |