The global monsoon across time scales: Mechanisms and outstanding issues

• Published in: Earth-Science Reviews
• Main Authors: Wang, Pin Xian, Wang, Bin, Cheng, Hai, Fasullo, John, Guo, ZhengTang, Kiefer, Thorsten, Liu, ZhengYu
• Other Authors: Wang, PX (reprint author), Tongji Univ, State Key Lab Mar Geol, Shanghai 200092, Peoples R China.; Wang, B (reprint author), Nanjing Univ Informat Sci & Technol, Earth Syst Modeling Ctr, Nanjing 210044, Jiangsu, Peoples R China., Tongji Univ, State Key Lab Mar Geol, Shanghai 200092, Peoples R China., Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Dept Atmospher Sci, Honolulu, HI 96825 USA., Nanjing Univ Informat Sci & Technol, Earth Syst Modeling Ctr, Nanjing 210044, Jiangsu, Peoples R China., Xi An Jiao Tong Univ, Inst Global Environm Change, Xian 710049, Shaanxi, Peoples R China., Univ Minnesota, Dept Earth Sci, Minneapolis, MN 55455 USA., CAS, Natl Ctr Atmospher Res, 3090 Ctr Green Dr, Boulder, CO 80301 USA., Chinese Acad Sci, Inst Geol & Geophys, Key Lab Cenozo Geol & Environm, POB 9825, Beijing 100029, Peoples R China., UPMC, CNRS, Global Hub Paris, Future Earth, 4 Pl Jussieu, F-75005 Paris, France., Peking Univ, Sch Phys, Lab Climate Ocean & Atmospher Studies, Beijing 100871, Peoples R China., Univ Wisconsin, Ctr Climat Res, Madison, WI 53706 USA., Wang, B (reprint author), Nanjing Univ Informat Sci & Technol, Earth Syst Modeling Ctr, Nanjing 210044, Jiangsu, Peoples R China.
• Format: Journal/Newspaper
• Language: English
• Published: EARTH-SCIENCE REVIEWS 2017
• Subjects: Monsoon; Climate variability; Monsoon mechanism; Hydrological cycle; Solar insolation; Precipitation; ASIAN SUMMER MONSOON; LAST GLACIAL MAXIMUM; SEA-SURFACE TEMPERATURE; PACIFIC WARM POOL; SOUTH CHINA SEA; ABRUPT CLIMATE-CHANGE; ATLANTIC MULTIDECADAL OSCILLATION; NORTHERN-HEMISPHERE GLACIATION; INTERTROPICAL CONVERGENCE ZONE; PMIP2 COUPLED SIMULATIONS; Pacific; Ice Sheet
• Online Access: https://hdl.handle.net/20.500.11897/484536; https://doi.org/10.1016/j.earscirev.2017.07.006

The present paper addresses driving mechanisms of global monsoon (GM) variability and outstanding issues in GM science. This is the second synthesis of the PAGES GM Working Group following the first synthesis "The Global Monsoon across Time Scales: coherent variability of regional monsoons" published in 2014 (Climate of the Past, 10, 2007-2052). Here we introduce the GM as a planetary scale circulation system and give a brief accounting of why it exhibits regional structure. The primary driver of the GM is solar insolation, and the specific features in the underlying surface, such as land-sea distribution, topography, and oceanic circulations, are mainly responsible for the differences among regional monsoon systems. We then analyze the monsoon formation mechanisms, together with the major processes that drive monsoon variations at various timescales, including external forcings and internal feedbacks. On long time scales, external forcings often induce variability on a global scale, whereas short-term variability in regional monsoon systems is usually caused by internal feedbacks within the climate system. Finally, a number of debatable issues are discussed, with an emphasis on time scales beyond the instrumental record. These include the dual nature of the monsoon as wind and rain, the meaning of oxygen isotope in hydrological cycle, in particular of speleothem delta O-18, the role of ice-sheet in monsoon variations, etc. In general, the GM as a system comprises a hierarchy of regional and local monsoons with various degrees of similarity, though all show coherent variability driven by a common solar forcing. The goal of the GM concept, therefore, is by no means to replace or diminish research on the regional monsoons, but to help dissect the mechanisms and controlling factors of monsoon variability at various temporal-spatial scales. PAGES project; NNSFC [91128000, 41371209, 41420104002]; NRF of Korea through Korean Ministry of Education, Science and Technology (MEST) [2011-0021927] SCI(E) REVIEW 84-121 174