ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 23, NO. 2, 2006, 258–266 Impact of Topography and Land-Sea Distribution on East Asian Paleoenvironmental Patterns ZHANG Zhongshi ∗1,2 ( ), WANG Huijun 2 ( ), GUO Zhengtang 3,1 ( ), and JIANG Dabang 2 ( ) 1 Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 2 Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 3 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075 (Received 12 May 2005; revised 24 June 2005) ABSTRACT Much geological research has illustrated the transition of paleoenvironmental patterns during the Cenozoic from a planetary-wind-dominant type to a monsoon-dominant type, indicating the initiation of the East Asian monsoon and inland-type aridity. However, there is a dispute about the causes and mechanisms of the transition, especially about the impact of the Himalayan/Tibetan Plateau uplift and the Paratethys Sea retreat. Thirty numerical sensitivity experiments under different land-sea distributions and Himalayan/Tibetan Plateau topography conditions are performed here to simulate the evolution of climate belts with emphasis on changes in the rain band, and these are compared with the changes in the paleoenvironmental patterns during the Cenozoic recovered by geological records. The consistency between simulations and the geological evidence indicates that both the Tibetan Plateau uplift and the Paratethys Sea retreat play important roles in the formation of the monsoon-dominant environmental pattern. Furthermore, the simulations show the monsoon-dominant environmental pattern comes into being when the Himalayan/Tibetan Plateau reaches 1000–2000 m high and the Paratethys Sea retreats to the Turan Plate. Key words: Paratethys Sea retreat, Himalayan/Tibetan Plateau uplift, paleoenvironmental pattern, pre- cipitation field, Turan Plate doi: 10.1007/s00376-006-0258-0 1. Introduction Previous geological studies (Zhou, 1982; Wang, 1990; Liu and Guo, 1997; Zhang and Guo, 2005) have illustrated that the Paleogene paleoenvironmental pat- tern in China was dominated by roughly-zonal cli- mates resulting from the planetary wind system (Fig. 1a). Conspicuous changes had occurred for the Neo- gene when the originally-arid southwestern and south- eastern parts of the country became much more hu- mid and the geographic location of the arid region in the northern part of China was closer to the present- day one (Fig. 1b), indicating the initiation of the East Asian monsoon and inland-type aridity. The Paleogene paleoenvironmental pattern was called the “planetary-wind-dominant type” and the Neogene pa- leoenvironmental pattern was called the “monsoon- dominant type” by geologists (Guo, 2003; Zhang and Guo, 2005). *E-mail: zhongshizhang@mail.iggcas.ac.cn