Critical frequency foF2 variability over Mexico

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Critical frequency foF2 variability over Mexico

• C. Cipagauta1, S. Pulinets1,2
• Institute of Geophysics, UNAM, Mexico
• IZMIRAN, RAS, Russia

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Outline

• Analysis details
• Solar cycle variability
• Seasonal variability
• LT variability
• Storm-time variability
• Dead-zone conception
• Future work

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Ionosonde position in relation to equatorial
anomaly
19.3 N (28.25 N), 100 W
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Data base

• Data for the whole solar cycle 1973, 1974, 1975,
  1976, 1977 LSA, 1972, 1978, 1982 MSA, 1979,
  1980, 1981 HSA
• Hourly values of foF2 (days per month 20 30,
  weekends no data)
• Local time 22-02 LT 05-07 LT 10-14 LT and 18-20
  LT

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Annual variations
LSA
MSA
HSA
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Seasons vs Solar activity
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Solar activity vs Seasons
Winter anomaly appears only before noon
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Ionosphere variability index 1
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Ionosphere variability index 2
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Ionosphere variability index 3
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Variability by seasons
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Storm-time positive variations
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Storm-time negative variations
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Counter phase storm-time variations
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Dead zone effect
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Statistical storm-time effect
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Storm-time variations and solar activity
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Storm-time variations and the local time
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Dead zone shown by IK-19 data
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Conclusions

• General morphology of foF2 variability in Mexico
  for the whole solar cycle is obtained
• Very weak storm-time variations (especially the
  negative phase) are revealed
• Magnetic equator inclination is probably
  responsible for the formation of additional
  northern crest structure and formation of the
  dead zone