Diversity of Tropical Intraseasonal Oscillation

热带地区的大尺度大气环流在几个月的时间尺度上有强烈的波动。这种热带季内振荡（ISO）主要是11 - 4月间的Madden-Julian振荡（MJO）现象和6 - 10月间的北方夏季季内振荡（BSISO）现象。MJO通常会引起向东发展的强降雨（和深云）模式，而BSISO则会产生向东北迁移的强降雨模式。这两种现象都极大地影响着全球的天气和气候。最近的观测表明，与MJO/BSISO相关的事件非常多样，在结构、传播、生命周期和全球影响方面存在显著差异。表征和了解ISO多样性及其气候变化对于全球大气变化的现实模拟和熟练预测至关重要。然而，到目前为止，它们在很大程度上是未知的。因此，本研究旨在揭示ISO多样性的独特形式及其对极端天气事件的影响，并了解其多样性及其年代际变率和未来变化的基本过程。这项研究的结果可以为热带动态和季风提供新的线索，并改善受ISO影响的超过10亿人口地区的天气和气候预报。该研究人员计划举办一次国际研讨会，以激发社区对ISO的兴趣。他将指导一名博士后研究科学家，并培养一名研究生。具体的研究目标是：(a)检测和表征ISO多样性的起源、传播、结构、放大/衰减和影响；(b)阐明导致ISO多样性行为产生的机制；(c)揭示ISO年代际变化的全球和区域来源；(d)量化ISO多样性对人为强迫的响应。为了实现这些目标，研究人员将采用一种结合过程和动态导向诊断、理论分析和建模的策略。这项工作的结果可能会为理解ISO复杂性提供一个新的概念框架，并为揭示ISO年代际变率及其未来变化的根本原因提供一个新的途径。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The large-scale atmospheric circulation in the tropical region strongly fluctuates on a timescale of a few months. Such tropical intraseasonal “oscillation” (ISO) is dominated by the Madden-Julian Oscillation (MJO) phenomenon between November-April and the Boreal Summer Intraseasonal Oscillation (BSISO) phenomenon between June-October. The MJO typically elicits patterns of enhanced rainfall (and deep clouds) that evolve eastward while BSISO produces northeastward migrating intense rainfall patterns. Both phenomena greatly impact weather and climate worldwide. Recent observations have revealed that events associated with MJO/BSISO are quite diverse, differing strikingly in structure, propagation, lifecycle, and global impacts. Characterization and understanding of ISO diversities and their climate variations are crucial for realistic modeling and skillful prediction of global atmospheric variations. However, to date, they are largely unknown. Thus, this research aims to reveal the distinctive forms of ISO diversity and its impacts on extreme weather events, and to understand the fundamental processes governing the diversity and its decadal variability and future change. Results from this research can shed new light on tropical dynamics and monsoons as well as improve weather and climate forecasting for regions of over 1 billion people impacted by ISO. The researcher plans to host an international workshop to galvanize community interests in ISO. He will mentor a post-doctoral research scientist and train a graduate student.The specific research objectives are to: (a) detect and characterize a full range of ISO diversity in their initiation, propagation, structure, amplification/decay, and impacts, (b) elucidate the mechanisms responsible for generation of the diversified ISO behavior, (c) reveal global and regional sources of ISO decadal variability, and (d) quantify how the ISO diversity responds to anthropogenic forcing. To address these objectives, the researcher will employ a strategy of combining process- and dynamics-oriented diagnostics, theoretical analyses, and modeling. Results from this work may lead to a new conceptual framework for understanding ISO complexity and a new avenue to unravel root causes of ISO decadal variability and its future change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.