Controls on South Pacific Convergence Zone Precipitation and Its Variability

本项目研究南太平洋辐合带（SPCZ），这是赤道以南的一大片云和降雨区域，从西太平洋（暖池区）经过斐济和美属萨摩亚向东南延伸至约30S， 140W。人们对产生SPCZ的基本动力学仍然知之甚少，气候模式很难正确地模拟它（模拟的SPCZ往往太面向纬向，太靠近赤道）。本项目有两个目标：第一，诊断在观测、再分析数据集和当前一代耦合气候模式（来自耦合模式比对项目第5版）的模拟中明显存在的多尺度SPCZ环流-湿度-降水关系。其次，利用包裹弥散模式建立了SPCZ区域气团轨迹气候学。将产生和分析气团与SPCZ相互作用路径的完全三维拉格朗日视角，其动机是进入SPCZ的干燥空气流动的变化驱动了该地区的降水变化。除了它的科学价值之外，这项工作预计将产生南太平洋决策者和利益相关者感兴趣的结果，他们将从更好地了解该地区易受洪涝和干旱影响的降雨变化中受益。太平洋环境与可持续发展中心将作为这个项目的PI与南太平洋研究人员、预报员和决策者之间相互作用的场所。该项目还促进国际合作，包括与澳大利亚气象局的合作，以及一名具有拉格朗日轨迹分析专业知识的哥斯达黎加科学家的参与。此外，该项目支持和培训研究生，从而为该研究领域的未来劳动力提供支持。

This project studies the South Pacific Convergence Zone (SPCZ), a large region of cloudiness and rainfall south of the equator extending southeastward from the Western Pacific (the warm pool region) past Fiji and American Samoa to about 30S, 140W. The basic dynamics that produce the SPCZ are still poorly understood, and climate models have difficulty in simulating it correctly (the simulated SPCZ is often too zonally oriented and too close to the equator). This project has two objectives: first, to diagnose multiscale SPCZ circulation-moisture-precipitation relationships evident in observations, reanalysis datasets, and simulations of current generation coupled climate models (from the Coupled Model Intercomparison Project version 5). Second, to develop an SPCZ region air mass trajectory climatology using a parcel dispersion model. A fully 3-dimensional, Lagrangian perspective of the pathways of air masses interacting with the SPCZ will be produced and analyzed, motivated by the idea that variations in the flow of dry air into the SPCZ drives precipitation variability in the region.Aside from its scientific merit, the work is expected to produce results of interest to decision makers and stakeholders in the South Pacific, who would benefit from better understanding of rainfall variability given vulnerability to floods and droughts in the region. The Pacific Centre for Environmental and Sustainable Development (PACE-SD) will serve as a venue for interactions between the PI of this project and South Pacific researchers, forecasters, and decision makers. The project also fosters international collaborations, including collaborations with the Australian Bureau of Meteorology and the participation of a Costa Rican scientist with expertise on Lagrangean trajectory analysis. In addition, the project supports and trains a graduate student, thereby providing for the future work force in this research area.