Researchers have discovered that interactions between westerlies and the Tianshan-Pamir Plateau set hydroclimate patterns in Central Asia 25 million years ago.

Central Asia constitutes the largest extratropical arid zone on Earth, while the time and mechanism of this unique climate regime remain controversial, according to a research article recently published in the journal Geology.

Integrated with geological evidence and climate simulations, the researchers from Lanzhou University, the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences and their cooperators found that a significant part of the Tianshan-Pamir Plateau reached elevations of about 3,000 meters and acted as a moisture barrier for the westerlies for 25 million years.

This major reorganization of atmospheric and topographic configuration played the leading role in shaping climate patterns in Central Asia, said Wang Xin with Lanzhou University. The western side of the Tianshan-Pamir Plateau has been characterized by a wetter climate for 25 millions years, whereas the eastern side has been characterized by more arid conditions.

Furthermore, the western side of the plateau had a winter-spring precipitation maxima, while the eastern side witnessed a summer precipitation maxima, said the article.