Energetic Constraints on the Width of the Intertropical Convergence Zone
Energetic Constraints on the Width of the Intertropical Convergence Zone
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DOI：
10.1175/jcli-d-15-0767.1
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发表时间：
2016-07-01
影响因子：
4.9
通讯作者：
Schneider, Tapio
中科院分区：
文献类型：
--
作者：
Byrne, Michael P.;Schneider, Tapio
热带辐合带（ITCZ）是近年来大量研究的焦点，其中大部分工作涉及热带最大降水的纬度如何响应自然气候变率和辐射强迫。然而，ITCZ的宽度却很少受到关注，尽管它对区域气候和理解大气环流非常重要。本文研究了ITCZ宽度在模拟与理想化的大气环流模式在很大范围内的气候。ITCZ被定义为时间平均上升的热带地区，随着气候的变化，ITCZ表现出丰富的行为，在凉爽气候中随着变暖而扩大，在温带气候中缩小，在炎热气候中保持相对恒定的宽度。的哈德利环流的质量和能量的预算是用来推导表达式的ITCZ面积相对于邻近的下降区的面积，和ITCZ面积的气候变化的敏感性。ITCZ的宽度主要取决于四个量：输入到热带大气的净能量，Hadley环流的湿静能平流，瞬变涡旋的湿静能输送和总湿稳定度。不同的过程是重要的ITCZ宽度在不同的气候，总的湿稳定性的变化一般有一个相对于其他过程的影响很弱。这些结果对于分析复杂气候模式中ITCZ的宽度以及了解热带地区过去和未来的气候变化可能是有用的。
The intertropical convergence zone (ITCZ) has been the focus of considerable research in recent years, with much of this work concerned with how the latitude of maximum tropical precipitation responds to natural climate variability and to radiative forcing. The width of the ITCZ, however, has received little attention despite its importance for regional climate and for understanding the general circulation of the atmosphere. This paper investigates the ITCZ width in simulations with an idealized general circulation model over a wide range of climates. The ITCZ, defined as the tropical region where there is time-mean ascent, displays rich behavior as the climate varies, widening with warming in cool climates, narrowing in temperate climates, and maintaining a relatively constant width in hot climates. The mass and energy budgets of the Hadley circulation are used to derive expressions for the area of the ITCZ relative to the area of the neighboring descent region, and for the sensitivity of the ITCZ area to changes in climate. The ITCZ width depends primarily on four quantities: the net energy input to the tropical atmosphere, the advection of moist static energy by the Hadley circulation, the transport of moist static energy by transient eddies, and the gross moist stability. Different processes are important for the ITCZ width in different climates, with changes in gross moist stability generally having a weak influence relative to the other processes. The results are likely to be useful for analyzing the ITCZ width in complex climate models and for understanding past and future climate change in the tropics.