Earth Science Frontiers ›› 2009, Vol. 16 ›› Issue (6): 226-239.

• Article • Previous Articles     Next Articles

Modeling the East Asian climate during the Late Cretaceous (80 Ma).

 CHEN Jun-Meng, DIAO Beng, WANG Cheng-Shan, HUANG Yong-Jian   

  1. 1Graduate School of Chinese Academy of Sciences, Beijing 100049, China
    2Chinese Academy of Meteorological Sciences, Beijing 100081, China
    3National Meteorological Information Centre, China Meteorological Administration, Beijing 100081, China
    4Research Center for Tibetan Plateau Geology, China University of Geosciences (Beijing), Beijing 100083, China
  • Received:2009-06-18 Revised:2009-10-12 Online:2009-12-16 Published:2009-12-10

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Abstract:

In this paper, the East Asian climate during the Late Cretaceous (80 Ma) is examined by using the Community Climate System Model Version 2 (CCSM2) from the National Center for Atmospheric Research (NCAR) and the reconstructed palaeogeographic data. The simulation results show that the largescale prevailing wind directions and pressure systems over East Asia showed a remarkable seasonal variation during 80 Ma, so that it can be inferred that there existed a monsoon circulation over East Asia at that time. Compared to the present climate, the atmospheric circulation systems over the Eurasian continent in the Late Cretaceous showed a stronger meridional feature, which possibly corresponded to a smaller zonal span of the continent. Moreover, under a warmer background in the Late Cretaceous, the winter and summer monsoons over East Asia showed a synchronous variation, with a stronger winter monsoon as well as a stronger summer monsoon. The pattern of annual mean precipitation is similar to that of the present climate, with the maximum precipitation appearing in the intertropical convergence zone (ITCZ) between 10°S and 10°N. There was also more precipitation over the eastern coasts of the continent adjacent to the western Pacific, with the central value exceeding 1200 mm, and there was less precipitation in the mid latitudes of the inland areas. Although a more precipitation belt also appeared near 30°N over the western Pacific, which is similar to the present climate, there was no precipitation belt over the land of East Asia. This feature implies that the uplift of the Tibetan Plateau plays an important role in the formation of the present baiu rain (plum rains). Moreover, the simulated climate over East Asia during 80 Ma was warmer relative to the present one and surface air temperature is 2 ℃ higher at the same latitudes compared to the present climate; the simulated temperature is close to the estimation from the geological evidence.

Key words: Late Cretaceous; greenhouse climate; paleoclimate modeling