Very-long-period oscillations in the atmosphere (0–110 km) – Part 2: Latitude– longitude comparisons and trends
<p>Measurements of atmospheric temperatures show a variety of long-term oscillations. These can be simulated by computer models and exhibit multi-annual, decadal, and even centennial periods. They extend from the ground up to the lower thermosphere. Recent analyses have shown that they exist i...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/3267/2023/acp-23-3267-2023.pdf |
| Summary: | <p>Measurements of atmospheric temperatures show a variety of long-term
oscillations. These can be simulated by computer models and exhibit
multi-annual, decadal, and even centennial periods. They extend from the
ground up to the lower thermosphere. Recent analyses have shown that they
exist in the models even if the model boundaries are kept constant with
respect to influences of the sun, ocean, and greenhouse gases. Therefore,
these parameters appear not to be responsible for the excitation of these
oscillations, i.e. the oscillations might be rather self-excited. However,
influences of land surface and vegetation changes had not been entirely
excluded. This is studied in the present analysis. It turns out that such
influences might be active in the lowermost atmospheric levels.</p>
<p>Long-term trends of atmospheric parameters such as the temperature are important
for the understanding of the ongoing climate change. Their study is mostly
based on data sets that are 1 to a few decades long. The trend values are
generally small and so are the amplitudes of the long-period oscillations.
It can therefore be difficult to disentangle these structures, especially if
the interval of trend analysis is comparable to the period of the oscillations. If the oscillations are self-excited, there may be a
non-anthropogenic contribution to the climate change which is difficult to
determine. Long-term changes of the cold-point tropopause are analysed here
as an example.</p> |
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| ISSN: | 1680-7316 1680-7324 |