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- Title
External Forcings Caused the Tripole Trend of Asian Precipitation During the Holocene.
- Authors
Xu, Hongna; Wang, Tao; Wang, Huijun; Chen, Shengqian; Chen, Jianhui
- Abstract
To investigate the evolution of precipitation over Asian continent in the Holocene and the associated mechanisms, we used a set of simulations of the transient climate evolution over the past 21,000 years (TraCE‐21ka), multimodel results from the Paleoclimate Modeling Intercomparison Project Phase 4 (PMIP4), and proxy records in Asia. The TraCE‐21ka results showed a tripole pattern in suborbital‐scale precipitation trends over the Asian continent during the Holocene, with a trend of increase over southern parts of the monsoon regions and arid Central Asia (ACA), and a trend of decline over northern parts of the monsoon regions and their areas of transition with ACA. This tripole pattern was corroborated by proxy records from multiple regions and multimodel results from the PMIP4. Further analysis based on single‐forcing simulations of TraCE‐21ka indicated that influences from different external forcings were different on the Asian precipitation in the main rainy seasons in the Holocene and that their combined effects shaped the tripole pattern. In summer, orbital forcing, by reducing solar radiation in mid‐to‐high latitudes and weakening the land‐sea thermal contrast, has been the dominant factor in the long‐term evolution of precipitation in the monsoon region and West Asia. In winter and spring, changes in meltwater flux played dominant roles in intensifying local water cycle and horizontal moisture advection, which drove the trend of increase in precipitation in ACA. Additionally, changes in greenhouse gas concentration and continental ice sheet forcings both also contribute to the increase in precipitation in ACA. Plain Language Summary: The change in precipitation in Asia plays an important role in shaping the pattern of the natural environment and affecting the development of human civilization. However, our understanding of the precipitation evolution in some regions of Asia in the Holocene remains of controversy, and the factors that govern the long‐term changes in Asian precipitation are not fully understood. Simulations and proxy data used in this study revealed a tripole pattern in the trend of precipitation in Asia during the Holocene. The pattern features a trend of increase in precipitation over southern parts of the monsoon regions and arid Central Asia (ACA), and a trend of decline in precipitation over northern parts of the monsoon regions and their areas of transition with ACA. Further analyses showed that solar insolation changes induced by the Earth's orbital movements have dominated the long‐term evolution of precipitation in the Asian monsoon region, and that the increasing greenhouse gas concentration, the changes in topography and extent of the retreating continental ice sheet over the Northwestern Europe and North America, and especially the decreasing amount of freshwater into oceans due to the retreating ice sheets have contributed to the increase in precipitation in ACA. Key Points: Both simulations and proxy records reveal a tripole pattern in suborbital‐scale precipitation trends over Asia during the HoloceneTripole pattern in precipitation trend reflects the combined effects of various external forcings during the HoloceneOrbital forcing dominates precipitation trend in the monsoon region, while meltwater flux dominates precipitation trend in the arid region
- Subjects
ASIA; CENTRAL Asia; HOLOCENE Epoch; ARID regions; ICE sheets; LONG-Term Evolution (Telecommunications); HYDROLOGIC cycle; MONSOONS
- Publication
Journal of Geophysical Research. Atmospheres, 2023, Vol 128, Issue 21, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2023JD039460