Trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphere
The continuous increase in concentration of greenhouse gases in the atmosphere is expected to cool higher levels of the atmosphere. There is some direct and indirect experimental evidence of long-term trends in temperature and other parameters in the mesosphere and lower thermosphere (MLT). Here...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
1999-10-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/17/1336/1999/angeo-17-1336-1999.pdf |
| _version_ | 1819266720489013248 |
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| author | J. Laštovička J. Laštovička D. Pancheva D. Pancheva |
| author_facet | J. Laštovička J. Laštovička D. Pancheva D. Pancheva |
| author_sort | J. Laštovička |
| collection | DOAJ |
| description | The continuous increase in concentration of
greenhouse gases in the atmosphere is expected to cool higher levels of the
atmosphere. There is some direct and indirect experimental evidence of long-term
trends in temperature and other parameters in the mesosphere and lower
thermosphere (MLT). Here we look for long-term trends in the annual and
semiannual variations of the radio wave absorption in the lower ionosphere,
which corresponds to the MLT region heights. Data from central and southeastern
Europe are used. A consistent tendency to a positive trend in the amplitude of
the semiannual wave appears to be observed. The reality of a similar tendency in
the amplitude of the annual wave is questionable in the sense that the trend in
the amplitude of the annual wave is probably induced by the trend in the yearly
average values of absorption. The phases of both the annual and semiannual waves
display a forward tendency, i.e. shift to an earlier time in the year. A
tentative interpretation of these results in terms of changes of the seasonal
variation of temperature and wind at MLT heights does not contradict the trends
observed in those parameters.<br><br><b>Key words.</b> Ionosphere (ionosphere – atmosphere
interactions; mid-latitude ionosphere) · Meteorology and atmospheric dynamics
(middle atmosphere dynamics) |
| first_indexed | 2024-12-23T21:05:46Z |
| format | Article |
| id | doaj.art-4695f0ee17a44e49be703dac6e765ddc |
| institution | Directory Open Access Journal |
| issn | 0992-7689 1432-0576 |
| language | English |
| last_indexed | 2024-12-23T21:05:46Z |
| publishDate | 1999-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Annales Geophysicae |
| spelling | doaj.art-4695f0ee17a44e49be703dac6e765ddc2022-12-21T17:31:13ZengCopernicus PublicationsAnnales Geophysicae0992-76891432-05761999-10-01171336134310.1007/s00585-999-1336-2Trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphereJ. Laštovička0J. Laštovička1D. Pancheva2D. Pancheva3Institute of Atmospheric Physics, Academy of Science of the Czech Republic, Bocni II, CZ-14131 Prague 4, Czech RepublicE-mail: jla@ufa.cas.czDepartment of Physics, University of Wales, Aberystwyth, Ceredigion SY23 3BZ, UKOn leave of absence from Geophysical Institute, Bulgarian Academy Science, Acad. G. Bonchev str. bl. 3, BG-1113 Sofia, BulgariaThe continuous increase in concentration of greenhouse gases in the atmosphere is expected to cool higher levels of the atmosphere. There is some direct and indirect experimental evidence of long-term trends in temperature and other parameters in the mesosphere and lower thermosphere (MLT). Here we look for long-term trends in the annual and semiannual variations of the radio wave absorption in the lower ionosphere, which corresponds to the MLT region heights. Data from central and southeastern Europe are used. A consistent tendency to a positive trend in the amplitude of the semiannual wave appears to be observed. The reality of a similar tendency in the amplitude of the annual wave is questionable in the sense that the trend in the amplitude of the annual wave is probably induced by the trend in the yearly average values of absorption. The phases of both the annual and semiannual waves display a forward tendency, i.e. shift to an earlier time in the year. A tentative interpretation of these results in terms of changes of the seasonal variation of temperature and wind at MLT heights does not contradict the trends observed in those parameters.<br><br><b>Key words.</b> Ionosphere (ionosphere – atmosphere interactions; mid-latitude ionosphere) · Meteorology and atmospheric dynamics (middle atmosphere dynamics)https://www.ann-geophys.net/17/1336/1999/angeo-17-1336-1999.pdf |
| spellingShingle | J. Laštovička J. Laštovička D. Pancheva D. Pancheva Trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphere Annales Geophysicae |
| title | Trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphere |
| title_full | Trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphere |
| title_fullStr | Trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphere |
| title_full_unstemmed | Trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphere |
| title_short | Trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphere |
| title_sort | trends in the characteristics of the annual and semiannual variations observed in the radio wave absorption in the lower ionosphere |
| url | https://www.ann-geophys.net/17/1336/1999/angeo-17-1336-1999.pdf |
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