EGU2020-2961, updated on 12 Jun 2020
https://doi.org/10.5194/egusphere-egu2020-2961
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Identifying sources of changed precipitation in paleoclimate studies through moisture tracking: A case study for orbital extremes over the Mediterranean Sea

Ruud van der Ent1,2, Joyce Bosmans2,3, Rein Haarsma4, Sybren Drijfhout4,5,6, and Frits Hilgen2
Ruud van der Ent et al.
  • 1Delft University of Technology, Faculty of Civil Engineering and Geosciences, Water Management, Delft, Netherlands (r.j.vanderent@tudelft.nl)
  • 2Faculty of Geosciences, Utrecht University, Utrecht, Netherlands
  • 3Faculty of Science, Radboud University, Nijmegen, Netherlands (joyce.bosmans@ru.nl)
  • 4Royal Netherlands Meteorological Institute (KNMI), de Bilt, Netherlands
  • 5Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, United Kingdom
  • 6Faculty of Science, Utrecht University, Utrecht, Netherlands

Enhanced winter precipitation over the Mediterranean Sea at times of minimum precession and maximum obliquity could provide freshwater required to form orbitally-paced sedimentary cycles across the Mediterranean Sea floor, offering an alternative to monsoonal runoff. We investigate the sources of the enhanced winter precipitation by applying a moisture tracking model (WAM-2layers) on the results of idealized orbital extreme experiments with a state-of-the-art climate model (EC-Earth).

Tracking the moisture sources of the enhanced winter precipitation over the Mediterranean Sea shows that the source differs during the winter half year. In fall, the majority of the precession-induced precipitation increase originates from the Mediterranean itself. However, in late winter, the increase can be attributed to enhanced moisture advection from the Atlantic. This agrees with changes in evaporation and air-sea temperature differences over the Mediterranean. The obliquity-induced precipitation increase shows much less differences, with an equal contribution of local and Atlantic sources.

The mechanism behind the Atlantic source of moisture is not related to storm track activity, but to a weakened Azores High and slightly higher surface pressure over North Africa. The resulting anomalous circulation patterns generate enhanced Atlantic moisture transport towards the Mediterranean. Our combined climate and moisture tracking modelling approach thus provides an alternative mechanism for Atlantic sources of orbitally-paced Mediterranean precipitation changes.

The results of this study have been published in:

Bosmans, J. H. C., van der Ent, R. J., Haarsma, R. J., Drijfhout, S. S. and Hilgen, F. J.: Identifying sources of changed precipitation in paleoclimate studies through moisture tracking: A case study for orbital extremes over the Mediterranean Sea, Paleoceanogr. Paleoclimatology, accepted, doi:10.1029/2019PA003655, 2020.

The atmospheric moisture tracking through WAM-2layers revealed concrete information about the evaporative sources of enhanced/reduced precipitation. This method has not been previously applied in paleoclimate studies, but thus proved to be a powerful tool in attributing reasons for precipitation changes in addition to climate model experiments and classical meteorological analyses. New ideas for collaborations to apply this method in other (paleo)climate studies are welcome.

How to cite: van der Ent, R., Bosmans, J., Haarsma, R., Drijfhout, S., and Hilgen, F.: Identifying sources of changed precipitation in paleoclimate studies through moisture tracking: A case study for orbital extremes over the Mediterranean Sea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2961, https://doi.org/10.5194/egusphere-egu2020-2961, 2020

Comments on the presentation

AC: Author Comment | CC: Community Comment | Report abuse

Presentation version 2 – uploaded on 04 May 2020 , no comments
small updates
Presentation version 1 – uploaded on 03 May 2020 , no comments