Rapid Adjustments and Their Effects on Arctic Amplification

北极放大(AA)指的是北极相对于低纬度地区变暖的加剧。鉴于AA对一系列人类和自然系统的影响，理解引起AA的物理过程是至关重要的。这个项目测试了一种假设，即快速大气过程--也就是众所周知的“快速调整”--是AA发生的基础。这代表了对AA的一种新的思考方式，传统上，AA被归因于慢得多的过程，如海冰消失。因此，该项目将加强我们对AA及其潜在的物理机制的理解，并有可能从根本上重塑我们对这一现象的看法。该项目的更广泛影响将包括开发适用于高中地球科学或物理课程的气候建模新课程。尽管进行了严格的科学审查，但不同物理过程在推动北极放大(AA)方面的相对重要性仍不确定。到目前为止，大多数理解这些过程的研究都集中在长时间尺度上(例如，数十年或更长时间)。相比之下，这个项目关注的是AA的短时间尺度。更具体地说，该项目将检验这样一个假设，即对外部强迫的快速调整是AA发生的基础，外部强迫是对独立于全球平均地表温度变化的强迫的反应。这一假设将通过分析一系列新的和现有的全球气候模型(GCM)模拟来检验。该项目将提供迄今为止关于快速调整在AA中的作用的最系统的调查，潜在地改变目前对AA及其潜在的物理机制的理解。该项目还将更广泛地加强对快速调整的理解，包括二氧化碳和非二氧化碳强迫之间的区别，以及它们如何依赖于定义它们的方法(例如，“Gregory”回归与固定海洋表面温度GCM模拟)。为该项目创建的新的GCM模拟将免费提供给科学界，从而为项目范围外的科学发现做出贡献。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Arctic amplification (AA) refers to the enhanced warming of the Arctic relative to lower latitudes. Understanding the physical processes that give rise to AA is critical, given its impacts on a range of human and natural systems. This project tests the hypothesis that fast atmospheric processes – known as “rapid adjustments” – are fundamental to the occurrence of AA. This represents a new way of thinking about AA, which has traditionally been attributed to much slower processes such as sea-ice loss. The project thus will enhance our understanding of AA and its underlying physical mechanisms, and also has the potential to fundamentally reshape how we view this phenomenon. Broader impacts of the project will include the development of a new curriculum on climate modeling that will be suitable for use in high school Earth science or physics courses.Despite intense scientific scrutiny, the relative importance of different physical processes in driving Arctic amplification (AA) remains uncertain. Most studies to date to understand these processes have focused on long time scales (e.g., multidecadal and longer). This project, in contrast, focuses on the short time scales of AA. More specifically, the project will test the hypothesis that rapid adjustments to external forcing – which are the response to the forcing that is independent of global mean surface temperature change – are fundamental to the occurrence of AA. This hypothesis will be tested by analyzing a series of new and existing global climate model (GCM) simulations. The project will provide the most systematic investigation to date of the role of rapid adjustments in AA, potentially transforming current understanding of AA and its underlying physical mechanisms. The project will also enhance understanding of rapid adjustments more generally, including how they differ between CO2 and non-CO2 forcings, and how they depend on the method used to define them (e.g., “Gregory” regression versus fixed sea surface temperature GCM simulations). The new GCM simulations created for the project will be made freely available to the scientific community, thus contributing to scientific discovery beyond the scope of the project.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.