Open AccessEnhancement of dust source area during past glacial periods due to changes of the Hadley circulation
Author(s) -
Chylek Petr,
Lesins Glen,
Lohmann Ulrike
Publication year - 2001
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000jd900583
Subject(s) - hadley cell , glacial period , geology , middle latitudes , climatology , last glacial maximum , atmospheric circulation , atmospheric sciences , environmental science , climate change , oceanography , general circulation model , geomorphology
Tropical deserts (e.g., Sahara, Arabian desert, Australian desert) are located within the Hadley circulation. Most of the dust uplifted from these deserts is carried by trade winds and deposited in tropical oceans with very little, if any, transported to polar regions. During glacial periods the dust concentrations in polar ice cores were a factor of 10 to 100 higher than during interglacial periods, including the current Holocene. The early general circulation model simulations of the past glacial climate were not able to reproduce these high mineral dust concentrations; the most recent attempts achieve an increased dust transport to polar regions by extending dust source areas to higher latitudes. We present a hypothesis that during glacial periods the Hadley cell is confined closer to the equator. This contraction of the Hadley circulation leads to the geographical change of the boundary between the tropical and the midlatitude circulation regimes. During the glacial periods a considerable fraction of the current tropical deserts was located outside the region of the Hadley circulation. This allowed the dust to be uplifted and transported by midlatitude storm systems to the polar regions. We present a model for the contraction of the Hadley circulation during the past glacial periods based on the Schneider‐Lindzen and Held‐Hou model of symmetric tropical circulation and on the assumption that the tropical sea surface temperatures were lower during glacial periods than they are today.