A low-level circulation in the tropics
A low-level circulation in the tropics
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DOI：
10.1175/2007jas2463.1
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发表时间：
2008-03
影响因子：
3.1
通讯作者：
I. Folkins;S. Fueglistaler;G. Lesins;T. Mitovski
中科院分区：
文献类型：
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作者：
I. Folkins;S. Fueglistaler;G. Lesins;T. Mitovski
摘要 热带深对流系统在对流层中层强烈汇聚。赤道太平洋和加勒比地区各种罗文探空仪阵列的水平风测量用于计算对流活跃地区大型阵列（直径≥1000公里）的平均动力散度剖面。有点令人惊讶的是，根据这些阵列计算出的对流层中层散度的幅度通常很小。原则上，深对流系统的中层辐合可以在更大范围内通过背景晴空大气辐射质量通量的垂直变化或通过浅积云的发散来平衡。然而，对流层中层晴空质量通量的垂直变化很小，因此抵消散度必须由浅积云提供。在约 1000 公里的空间尺度上，中层向深层对流汇聚的流入似乎被来自外部的发散流出进行了内部补偿或“屏蔽”。
Abstract Deep convective tropical systems are strongly convergent in the midtroposphere. Horizontal wind measurements from a variety of rawinsonde arrays in the equatorial Pacific and Caribbean are used to calculate the mean dynamical divergence profiles of large-scale arrays (≥1000 km in diameter) in actively convecting regions. Somewhat surprisingly, the magnitude of the midtropospheric divergence calculated from these arrays is usually small. In principle, the midlevel convergence of deep convective systems could be balanced on larger scales either by a vertical variation in the radiative mass flux of the background clear sky atmosphere, or by a divergence from shallow cumuli. The vertical variation of the clear sky mass flux in the midtroposphere is small, however, so that the offsetting divergence must be supplied by shallow cumuli. On spatial scales of ∼1000 km, the midlevel convergent inflow toward deep convection appears to be internally compensated, or “screened,” by a divergent outflow from surr...