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

在每年的基础上，热带太平洋海表温度（SST）的变化主要是由厄尔尼诺/南方涛动（ENSO）事件主导的，这些事件已知会影响全球的天气模式，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率（TPDV）也被认为是全球影响的原因，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。目前的工作考察了TPDV的某些部分通过一种被称为整流的机制与ENSO活动有关的可能性，在整流机制中，与ENSO事件相关的洋流和海洋温度异常尽管具有短暂的性质，但却在热带太平洋上产生了持久的热量重新排列。重新排列的感觉是，ENSO整流导致西太平洋“暖池”、海洋大陆周围最大海温区和东太平洋沿赤道的“冷舌”区温度较低。PI假设，如果ENSO在较长一段时间内异常活跃，那么整流效应将导致赤道太平洋的平均状态，即东西海洋温度对比减弱，这对ENSO不利。结果将是ENSO活动的减少，导致较弱的整流效应，从而导致更强的东西温度对比。较强的温度对比更有利于ENSO活动，使ENSO活动恢复到较高水平并重复此循环。将使用不同配置的气候模式进行一系列实验，包括将一些地面风加到海洋成分模式上，以及将其他海温加到大气成分模式上，以检验这一假设。除了其科学意义外，TPDV起源的问题还具有重大的社会意义。如果提出的机制有助于TPDV和ENSO活动的年代际调制，它可能会改善ENSO事件的预测和减缓太平洋海温的变化。考虑到热带太平洋海温变化对全球的影响，这种预测将具有很大的价值。这项工作也可能有助于理解全球变暖的中断和预测其终止。此外，这项工作将支持和培养一名研究生，从而发展该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.