Impact of ocean tides on the climate system during the pre-industrial period, the early Eocene, and the Albian
Climate simulations for the coming century indicate higher global mean surface temperatures than at present day. Understanding of the dynamics of oceans, atmosphere, cryosphere, and vegetation in warm climates is therefore crucial for improving climate projections. Reconstructions based on proxy dat...
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| Other Authors: | , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2016
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| Online Access: | https://refubium.fu-berlin.de/handle/fub188/9841 https://doi.org/10.17169/refubium-14039 https://nbn-resolving.org/urn:nbn:de:kobv:188-fudissthesis000000100930-2 |
| Summary: | Climate simulations for the coming century indicate higher global mean surface temperatures than at present day. Understanding of the dynamics of oceans, atmosphere, cryosphere, and vegetation in warm climates is therefore crucial for improving climate projections. Reconstructions based on proxy data show that the early Eocene (∼55.8 to 48.6 million years ago) and the Albian (∼112.9 to 99.6 million years ago) were two warm periods characterized by global mean surface temperatures that were 8–12°C higher than at present day. Several plausible hypotheses intend to explain their reduced meridional temperature gradient; nevertheless, the mechanisms leading to this phenomenon are still not well understood. The atmosphere is strongly dependent on the boundary forcing from the ocean. The ocean circulation is affected by lunisolar tidal potential that induces long-term tidal residual mean currents and thereby influences the general ocean circulation. Through this process the advection of heat is altered in the ocean and, thus, the oceanic temperature distribution is modified. This alters mean sea surface conditions and thus the lower boundary conditions for sea ice and atmosphere. This means that both sea ice dynamics and the lower atmosphere are modified by oceanic tidal dynamics on climatological time-scales. Until now, most climate studies and all paleo- climate reconstructions have neglected the influence of tidal forcing on ocean and atmosphere dynamics. In this thesis, the coupled atmosphere-ocean model ECHAM5/MPIOM is employed to simulate the climate of a pre-industrial period, the early Eocene, and the Albian. Furthermore, lunisolar tidal forcing is included in the ocean model MPIOM in order to study, for the first time, the effects of tidal dynamics on the ocean and the atmosphere in a paleo-climatic context. The simulations of the early Eocene and the Albian reveal feedback mechanisms between sea ice and the heat flux from the ocean to the atmosphere that decrease the meridional temperature gradient. The ... |
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