JpGU-AGU Joint Meeting 2017

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[EE] Oral

A (Atmospheric and Hydrospheric Sciences) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS03] [EE] International Field Campaign - Years of the Maritime Continent (YMC)

Sun. May 21, 2017 9:00 AM - 10:30 AM 301A (International Conference Hall 3F)

convener:Kunio Yoneyama(Japan Agency for Marine-Earth Science and Technology / Department of Coupled Ocean-Atmosphere-Land Processes Research), Chidong Zhang(NOAA Pacific Marine Environmental Laboratory), Tetsuya Takemi(Disaster Prevention Research Institute, Kyoto University), Chairperson:Kunio Yoneyama(Japan Agency for Marine-Earth Science and Technology / Department of Coupled Ocean-Atmosphere-Land Processes Research)

9:30 AM - 9:45 AM

[AAS03-03] Barrier Effect of the Indo-Pacific Maritime Continent on the MJO: Perspectives from Tracking MJO Precipitation

★Invited papers

*Jian Ling1, Chidong Zhang2 (1.LASG/IAP, CAS, China, 2.PMEL, NOAA, US)

Keywords:MJO tracking, Maritime Continent, barrier effect

Explanations for the barrier effect of the Indo-Pacific Maritime Continent (MC) on the MJO should satisfy two criteria. First, they should include specific features of the MC, namely, its intricate land-sea distributions and elevated terrains. Second, they should include mechanisms for both the barrier effect and its overcoming by some MJO events. Guided by these two criteria, we applied a precipitation-tracking method to identify MJO events that propagate across the MC (MJO-C) and those that are blocked by the MC (MJO-B). About a half of MJO events that form over the Indian Ocean propagate through the MC. Most of them (> 75%) become weakened over the MC. The barrier effect cannot be explained in terms of the strength, horizontal scale, or spatial distribution of MJO convection when it approaches the MC from the west. A distinction between MJO-B and MJO-C is their precipitation over the sea vs. land in the MC region. MJO-C events rain more over the sea than over land, whereas land rainfall dominates for MJO-B. This suggests that inhibiting convective development over the sea could be a possible mechanism for the barrier effect of the MC. Preceding conditions for MJO-C include stronger low-level zonal moisture flux convergence and higher SST in the MC region. Possible connections between these large-scale conditions and the land vs. sea distributions of MJO rainfall through the diurnal cycle are discussed.