the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Simulating glacial dust changes in the Southern Hemisphere using ECHAM6.3-HAM2.3
Stephan Krätschmer
Michèlle van der Does
Frank Lamy
Gerrit Lohmann
Christoph Völker
Martin Werner
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For 1 century, the hemispheric summer insolation is proposed as a key pacemaker of astronomical climate change. However, an increasing number of geologic records reveal that the low-latitude hydrological cycle shows asynchronous precessional evolutions that are very often out of phase with the summer insolation. Here, we propose that the astronomically driven low-latitude hydrological cycle is not paced by summer insolation but by shifting perihelion.
Our study examines the Atlantic Meridional Overturning Circulation (AMOC) during the Last Glacial Maximum (LGM), a period with higher tidal dissipation. Despite increased tidal mixing, our model simulations show that the AMOC remained relatively shallow, consistent with paleoproxy data and resolving previous inconsistencies between proxy data and model simulations. This research highlights the importance of strong ocean stratification during the LGM and its interaction with tidal mixing.
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Scientists study past climate change using proxies (e.g. pollen) and models. Proxies offer detailed snapshots but are limited in number, while models provide broader coverage but at low resolution. Models are typically downscaled to 30 arcmin, but it is unclear if this is sufficient. We found that increasing models to 5 arcmin does not improve their coherence with climate reconstructed from pollen data. Optimal model resolution depends on research need, balancing detail with error.