Rectification of El Nino-Southern Oscillation as a Mechanism for the Tropical Pacific Decadal Variability: A Diabatic and Time-Dependent View

在一年一年的基础上，热带太平洋海表面温度(SST)的变化是由厄尔尼诺/南方涛动(ENSO)事件主导的，这些事件众所周知会影响世界各地的天气模式，并对美国产生重大影响。但热带太平洋海温的变化也可能更慢，热带太平洋年代际变化(TPDV)也被认为是造成全球影响的原因，包括20世纪30年代的大沙尘暴干旱和最近的全球变暖中断。本工作探讨了TPDV的一部分与ENSO活动有关的可能性，这种机制被称为整流，在这种机制中，与ENSO事件有关的洋流和海温异常，尽管是暂时性的，但仍会在热带太平洋产生持久的热量重新排列。这种重排的感觉是，ENSO整流导致西太平洋“暖池”、海洋大陆周围海温最高的区域和东太平洋赤道沿线的“冷舌”区域的温度较低。PI假设，如果ENSO异常活跃较长时间，其整流效应将导致赤道太平洋东西向海温反差较弱的平均态，这对ENSO不利。其结果将是ENSO活动减少，导致较弱的整流效应，从而导致较强的东西温差。温度反差越强，越有利于ENSO活动，使其回归到较强的ENSO活动，并重复循环。使用不同配置的气候模型的一系列实验将被用来检验这一假设。除了科学上的意义外，TPDV起源的问题还具有重大的社会意义。如果所提出的机制对ENSO活动的TPDV和年代际调制有贡献，则可能导致对ENSO事件的更好的预测和太平洋SST较慢的变化。鉴于热带太平洋海温变化在世界范围内的影响，这种预测将是非常有价值的。这项工作也可能有助于理解全球变暖间歇期并预测其终止。此外，这项工作将支持和培训一名研究生，从而培养这一研究领域的未来劳动力。

On a year-to-year basis the variability of sea surface temperature (SST) in the tropical Pacific is dominated by El Nino/Southern Oscillation (ENSO) events, which are known to influence weather patterns worldwide and have significant impacts on the US. But tropical Pacific SSTs can also vary more slowly, and tropical Pacific decadal variability (TPDV) has also been proposed as the cause of worldwide impacts including the great Dust Bowl drought of the 1930s and the recent global warming hiatus. The present work examines the possibility that some portion of TPDV is related to ENSO activity through a mechanism referred to as rectification, in which the ocean currents and ocean temperature anomalies associated with ENSO events, despite their transient nature, nevertheless produce a lasting rearrangement of heat across the tropical Pacific ocean. The sense of the rearrangement is such that ENSO rectification leads to cooler temperatures in the West Pacific "warm pool", the region of maximum SSTs around the Maritime Continent, and the "cold tongue" region along the equator in the eastern Pacific. The PI hypothesizes that if ENSO is unusually active for an extended period the rectification effect will lead to a mean state with a weaker east-west ocean temperature contrast across the equatorial Pacific, which is less favorable to ENSO. The result will be a reduction in ENSO activity, resulting in a weaker rectification effect that will lead to a stronger east-west temperature contrast. The stronger temperature contrast is more favorable to ENSO activity, producing a return to greater ENSO activity and repeating the cycle. A suite of experiments using a climate model in various configurations, including some with surface winds imposed on the ocean component model and others with SSTs imposed on the atmospheric component model, will be used to test the hypothesis.In addition to its scientific interest, the question of TPDV origins has substantial societal implications. If the proposed mechanism contributes to TPDV and decadal modulation of ENSO activity, it may lead to improved prediction of ENSO events and slower variations of Pacific SST. Such predictions would be of great value given the worldwide impacts of tropical Pacific SST variations. The work may also be helpful in understanding the global warming hiatus and anticipating its termination. In addition, the work will support and train a graduate student, thereby developing the future workforce in this research area.