USTC proposes new mechanisms of holocene east Asian monsoon precipitation

The precipitation patterns of East Asian monsoon (EAM) region have a great impact on economic development. However, former researchers have not reached an agreement on the driving mechanism of EAM variation.

Recently, the research team led by ZHOU Xin from University of Science and Technology of China (USTC) of the Chinese Academy of Sciences, proposed a time-transgressive pattern of the Holocene monsoon precipitation maximum (HMPM) in EAM region and proposed the possible driving mechanism. The paper was published in Geology.

The initial timing of the HMPM was calculated based on published quantitative records, which were reconstructed from pollen data in the EAM region. Previous researches attested that vegetation changed synchronously with lake levels, indicating that vegetation had a quick response to rainfall. The analysis showed that the HMPM occurred earlier in the southern area and later in the northern area. Further, the initial timing of the HMPM and latitude had a significant linearity.

Researchers then conducted profound analysis of modern spatiotemporal rainfall patterns, variation of insolation peaks and seasonal insolation period. Different from the previous view, researchers proposed that monsoon precipitation in the EAM region was not controlled by average summer insolation, but rather low-latitude seasonal insolation changes. The seasonal change was modulated by Western Pacific Subtropical High (WPSH), whose movement along the latitude was generally determined by seasonal insolation.

In summary, this work reconstructed the precipitation pattern in the EAM region during the Holocene and proposed the driving force of precipitation variation. It can promote deeper understanding of monsoon dynamics related to seasonal insolation changes.