Mechanisms for the Northward Displacement of the Pacific Intertropical Convergence Zone (ITCZ)

该项目将调查热带辐合带（ITCZ）离赤道位置的原因。东北信风和东南信风交汇产生水汽通量辐合，为热带深层对流提供补给。在卫星图像中，对流表现为明亮的云带，有助于识别ITCZ。尽管太阳强迫在年平均值上几乎是对称的，但在一年中的大部分时间里，太平洋中部/东部的ITCZ仍然在赤道以北。最近的研究揭示了赤道和沿海地区的海洋-大气相互作用以及大陆（如美洲）的地理不对称在产生北太平洋区域北半球位置方面的作用，但许多关键问题仍未得到解答。不足为奇的是，在目前的气候模式中，ITCZ仍然是一个模拟效果很差的特征。Drs。谢尚平和Tim Li将使用一对耦合气候模型，通过建模分析确定控制ITCZ位置的关键气候相互作用。pi将把美洲的地理不对称分解成几个元素，并在ITCZ的子午线位置的背景下研究它们“打破对称”的可能性。他们还将研究东太平洋区域与北美季风的相互作用。这项研究将促进对海洋、陆地和大气如何相互作用来塑造东太平洋气候的理解。这样，它将为美国国家科学基金会的东太平洋气候调查（EPIC）实地计划提供大规模的解释框架，也有助于美国CLIVAR计划的泛美/太平洋研究目标。

The project will investigate the causes for the off-equatorial location of the Inter-Tropical Convergence Zone (ITCZ). The confluence of northeast and southeast trade winds generates the moisture flux convergence that feeds deep tropical convection. The convection shows up as a bright cloud band in satellite pictures, and helps identify the ITCZ. Although solar forcing is nearly symmetric in the annual-mean, the ITCZ in the central/eastern Pacific remains northward of the equator throughout much of the year. Recent studies have revealed the role of ocean-atmosphere interactions in equatorial and coastal zones, and of geographical asymmetries of continents (e.g., the Americas) in producing the Northern hemisphere location of the ITCZ, but many key questions remain unanswered. Not surprisingly, the ITCZ remains a poorly simulated feature in current climate models. Drs. Shang-Ping Xie and Tim Li will identify the key climate interactions that control ITCZ location from modeling analysis, using a pair of coupled climate models. The PIs will decompose the geographical asymmetries of the Americas into several elements and investigate their "symmetry-breaking" potential in context of ITCZ's meridional position. They will also investigate the interaction of the eastern Pacific ITCZ and the North American monsoon. This research will advance the understanding of how ocean, land, and the atmosphere interact to shape the eastern Pacific climate. In so doing, it will provide the large-scale interpretive framework for NSF's Eastern Pacific Investigation of Climate (EPIC) field program, and also contribute to the Pan American/Pacific research goals of the U.S. CLIVAR program.