Preprints
https://doi.org/10.5194/cp-2022-76
https://doi.org/10.5194/cp-2022-76
 
18 Nov 2022
18 Nov 2022
Status: this preprint is currently under review for the journal CP.

South Asian summer monsoon enhanced by the uplift of Iranian Plateau in Middle Miocene

Meng Zuo1, Yong Sun2, Yan Zhao2, Gilles Ramstein3, Lin Ding2, and Tianjun Zhou1 Meng Zuo et al.
  • 1State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
  • 2Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, and Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China
  • 3Laboratoire des Sciences du Climat et de l’environnement, CNRS-CEA-UVSQ, 91191 Gif-sur-Yvette, France

Abstract. The South Asian summer monsoon (SASM) remarkably strengthened during the Middle Miocene (16–11 Ma), coincident with the rapid uplifts of the Iranian Plateau (IP) and the Himalaya (HM). Although the development of the SASM has long been linked to the topographic changes in the Tibetan Plateau (TP) region, the effects of the HM and IP uplift are still vigorously debated, and the underlying mechanisms remain unclear. Based on Middle Miocene paleogeography, we employ the fully coupled earth system model CESM to perform a set of topographic sensitivity experiments with altered altitudes of the IP and the HM. Our simulations reproduce the strengthening of the SASM in northwestern India and over the Arabian Sea, largely attributing to the thermal effect of the IP uplift. The elevated IP insulates the warm and moist airs from the westerlies in the south of the IP and produces a low-level cyclonic circulation around the IP, which leads to the convergence of the warm and moist air in the northwestern India and triggers positive feedback between the moist convection and the large-scale monsoon circulation, further enhancing the monsoonal precipitation. Whereas the HM uplift produces orographic precipitation without favorable circulation adjustment for the SASM. We thus interpret the intensification of the Middle Miocene SASM in the western part of the South Asia as a response to the IP uplift while the subtle SASM change in eastern India reflects the effects of the HM uplift.

Meng Zuo et al.

Status: open (until 13 Jan 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Meng Zuo et al.

Meng Zuo et al.

Viewed

Total article views: 213 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
160 46 7 213 3 4
  • HTML: 160
  • PDF: 46
  • XML: 7
  • Total: 213
  • BibTeX: 3
  • EndNote: 4
Views and downloads (calculated since 18 Nov 2022)
Cumulative views and downloads (calculated since 18 Nov 2022)

Viewed (geographical distribution)

Total article views: 206 (including HTML, PDF, and XML) Thereof 206 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 07 Dec 2022
Download
Short summary
Based on the coupled model simulations with realistic early to middle Miocene paleogeography, we reveal that the enhanced South Asian summer monsoon in Middle Miocene is mainly caused by the uplift of Iranian Plateau (IP), rather than the Himalayas. The elevated IP insulates the warm and moist airs in the south of the IP and produces a low-level cyclonic circulation, which leads to the convergence of the warm and moist air in the northwestern India and enhancing the monsoonal precipitation.