Publication Abstracts

Tierney et al. 2011

Tierney, J.E., S.C. Lewis, B.I. Cook, A.N. LeGrande, and G.A. Schmidt, 2011: Model, proxy and isotopic perspectives on the East African Humid Period. Earth Planet. Sci. Lett., 307, 103-112, doi:10.1016/j.epsl.2011.04.038.

Both North and East Africa experienced more humid conditions during the early and mid-Holocene epoch (11,000-5,000 yr BP; 11-5 ka) relative to today. The North African Humid Period has been a major focus of paleoclimatic study, and is now understood to represent a response of the hydrological cycle to the increase in boreal summer insolation and associated ocean, atmosphere and land surface feedbacks. Meanwhile, the mechanisms responsible for the coeval East African Humid Period are poorly understood. Here, we use results from isotope-enabled coupled climate modeling experiments to investigate the cause of the East African Humid Period. The modeling results are interpreted alongside proxy records of both water balance and the isotopic composition of rainfall. Our simulations show that the orbitally-induced increase in dry season precipitation and the subsequent reduction in precipitation seasonality can explain the East African Humid Period, and this scenario agrees well with regional lake level and pollen paleoclimate data. Changes in zonal moisture flux from both the Atlantic and Indian Ocean account for the simulated increase in precipitation from June through November. Isotopic paleoclimate data and simulated changes in moisture source demonstrate that the western East African Rift Valley in particular experienced more humid conditions due to the influx of Atlantic moisture and enhanced convergence along the Congo Air Boundary. Our study demonstrates that zonal changes in moisture advection are an important determinant of climate variability in the East African region.

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BibTeX Citation

  author={Tierney, J. E. and Lewis, S. C. and Cook, B. I. and LeGrande, A. N. and Schmidt, G. A.},
  title={Model, proxy and isotopic perspectives on the East African Humid Period},
  journal={Earth and Planetary Science Letters},

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RIS Citation

ID  - ti01100t
AU  - Tierney, J. E.
AU  - Lewis, S. C.
AU  - Cook, B. I.
AU  - LeGrande, A. N.
AU  - Schmidt, G. A.
PY  - 2011
TI  - Model, proxy and isotopic perspectives on the East African Humid Period
JA  - Earth Planet. Sci. Lett.
JO  - Earth and Planetary Science Letters
VL  - 307
SP  - 103
EP  - 112
DO  - 10.1016/j.epsl.2011.04.038
ER  -

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