Potential role of winter rainfall in explaining increased moisture in the Mediterranean and Middle East during periods of maximum orbitally-forced insolation seasonality

J. E. Kutzbach, G. Chen, H. Cheng, R. L. Edwards, Z. Liu

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117 Scopus citations


Precession-related forcing of seasonal insolation changes in the northern hemisphere (NH) alternates between maximum NH seasonality (summer perihelion-increased insolation; winter aphelion-decreased insolation) and minimum NH seasonality (summer aphelion, and winter perihelion). With maximum NH seasonality, climate models simulate stronger NH summer monsoons that bring increased precipitation to North Africa and South and East Asia, in agreement with the in-phase relation of precipitation and NH summer insolation found in many paleoclimatic records. However paleoclimatic records in parts of the Mediterranean, the Middle East, and the interior of Asia also indicate increased moisture at times of maximum NH seasonality, a change not always clearly linked to stronger summer monsoons-either because these regions are at or beyond the boundaries of the present-day monsoon or because the observations allow multiple causal interpretations, or both. This study focuses on the possible role of changes in NH winter climate in explaining these wetter episodes. Using climate model simulations, we show that the 'NH winter aphelion-decreased NH winter insolation' orbital configuration is linked to the Mediterranean storm track and increased winter rains in the Mediterranean, the Middle East, and interior Asia. We conclude that wetter periods at precession time scales in these particular regions may have resulted either from increased wintertime storm track precipitation, or from a combination of increased winter and summer rainfall. Given this seasonal ambiguity, both possibilities need to be considered.

Original languageEnglish (US)
Pages (from-to)1079-1095
Number of pages17
JournalClimate Dynamics
Issue number3-4
StatePublished - Feb 2014

Bibliographical note

Funding Information:
We acknowledge the support of National Science Foundation grants 090792,1103403, and 1211299 to the University of Minnesota, Chinese Ministry of Science and Technology Grant 2013CB955902 to Xi’an Jiaotong University, NSF (EAR) grant 0908117 to the University of Wisconsin-Madison, and the use of climate models and computer resources of the National Center for Atmospheric Research (NCAR)—which is supported by NSF. We thank B. Otto-Bliesner of NCAR for helping us access the NCAR climate model simulations for 125 ka (CCSM3, T85) and 6 ka (CCSM4). JEK thanks B. Otto-Bliesner and G. A. Meehl for helpful discussions on this topic while he was a summer visiting scientist at NCAR. We thank the anonymous reviewers for comments and suggestions that have helped us modify and improve the paper.


  • Eurasian paleoclimate
  • Milankovitch orbital cycles
  • Paleoclimate
  • Paleoclimate simulation
  • Paleoclimatic records
  • Speleothems


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