Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2018-24
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
17 Apr 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).
Understanding the Australian Monsoon change during the Last Glacial Maximum with multi-model ensemble
Mi Yan1,2, Bin Wang3,4, Jian Liu1,2, Axing Zhu1,2,5,6, and Liang Ning1,2,7 1Key Laboratory of Virtual Geographic Environment, Ministry of Education; State key Laboratory of Geographical Environment Evolution, Jiangsu Provincial Cultivation Base; School of Geography Science, Nanjing Normal University, Nanjing, 210023, China
2Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China
3Department of Atmospheric Sciences, University of Hawaii at Manoa, Honolulu, HI 96825, USA
4Earth System Modeling Center, Nanjing University of Information Science and Technology, Nanjing, 210044, China
5State Key Lab of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
6Department of Geography, University of Wisconsin-Madison, Madison, WI 53706, USA
7Climate System Research Center, Department of Geosciences, University of Massachusetts, Amherst, 01003, USA
Abstract. The response of Australian monsoon to the external forcings and the relative mechanisms during the Last Glacial Maximum (LGM) is investigated by multi-models in CMIP5/PMIP3. Although the annual mean precipitation over Australian monsoon region decreases, the annual range, or the monsoonality, is enhanced. The precipitation increases in early austral summer and decreases in austral winter, causing the annual range or monsoonality to amplify. The decreased precipitation in austral winter has a large contribution to the strengthened monsoonality. It is primarily caused by the weakened upward motion, although the reduced water vapor has also a moderate contribution. The weakened upward motion in austral winter is induced by the enhanced land–sea thermal contrast, which intensifies the divergence over northern Australia. The increased Australian monsoon rainfall in early summer is an integrated result of the positive effect of local dynamic processes (enhanced moisture convergence) and the negative effect of thermodynamics (reduced moisture content). The enhanced moisture convergence is caused by two factors: the strengthened northwest–southeast thermal contrast between the cooler Indochina–western Indonesia and the warmer northeastern Australia, and the east–west sea surface temperature gradients between the warmer western Pacific and cooler eastern Indian Ocean, both due to the alteration of land–sea configuration arising from the sea level drop. The enhanced Australian monsoonality in LGM is caused by the local processes rather than the large scale dynamics, which should be taken into account when investigating its future change under global warming. Our findings may also explain why proxy records indicate different changes in Australian monsoon precipitation during the LGM.
Citation: Yan, M., Wang, B., Liu, J., Zhu, A., and Ning, L.: Understanding the Australian Monsoon change during the Last Glacial Maximum with multi-model ensemble, Clim. Past Discuss., https://doi.org/10.5194/cp-2018-24, in review, 2018.
Mi Yan et al.
Mi Yan et al.

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