Scale Interactions between the MJO and the Western Maritime Continent
Scale Interactions between the MJO and the Western Maritime Continent
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DOI：
10.1175/jcli-d-15-0557.1
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发表时间：
2016-03
影响因子：
4.9
通讯作者：
C. Birch;S. Webster;Simon C. Peatman;D. Parker;A. Matthews;Y. Li;M. E. Hassim
中科院分区：
文献类型：
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作者：
C. Birch;S. Webster;Simon C. Peatman;D. Parker;A. Matthews;Y. Li;M. E. Hassim
国家的最先进的区域气候模式模拟，能够解决关键的中尺度环流，第一次，了解大尺度对流环境的MJO和过程之间的相互作用，管理强周日周期的海洋大陆（MC）的岛屿。下午晚些时候，由于海风的辐合，对流在沿海内陆持续存在。以前的工作已经表明，在MC降雨与MJO的变化表现在这个昼夜周期的变化，陆基降雨峰值前的活跃对流信封的MJO到达MC，而海洋降雨率峰值，而活跃的信封居住在该地区。模式模拟结果表明，在MJO活动初期，大尺度环境和大气稳定度是控制海洋MC降水的主要因素，而在MJO活动后期，高的近地面风强迫的高海洋潜热通量是控制海洋MC降水的主要因素。在陆地上，降雨量在主对流包络到达之前达到峰值（与观测结果一致），尽管大尺度对流环境仅对对流适度有利。这一早期降雨高峰的原因是由于高表面日照和表面加热而产生的强烈陆海空风环流的对流触发。在高峰期MJO阶段云量增加，地面日照减少，这削弱了中尺度环流的强度，减少了陆基降雨，即使大尺度环境仍然有利于对流在这个时候。因此，规模相互作用是跨MC的MJO过渡的重要组成部分。
State-of-the-art regional climate model simulations that are able to resolve key mesoscale circulations are used, for the first time, to understand the interaction between the large-scale convective environment of the MJO and processes governing the strong diurnal cycle over the islands of the Maritime Continent (MC). Convection is sustained in the late afternoon just inland of the coasts due to sea breeze convergence. Previous work has shown that the variability in MC rainfall associated with the MJO is manifested in changes to this diurnal cycle; land-based rainfall peaks before the active convective envelope of the MJO reaches the MC, whereas oceanic rainfall rates peak whilst the active envelope resides over the region. The model simulations show that the main controls on oceanic MC rainfall in the early active MJO phases are the large-scale environment and atmospheric stability, followed by high oceanic latent heat flux forced by high near-surface winds in the later active MJO phases. Over land, rainfall peaks before the main convective envelope arrives (in agreement with observations), even though the large-scale convective environment is only moderately favourable for convection. The causes of this early rainfall peak are convective triggers from land-sea breeze circulations that are strong due to high surface insolation and surface heating. During the peak MJO phases cloud cover increases and surface insolation decreases, which weakens the strength of the mesoscale circulations and reduces land-based rainfall, even though the large-scale environment remains favourable for convection at this time. Hence, scale interactions are an essential part of the MJO transition across the MC.