Assessing and Understanding Extratropical Control on Tropical Climate

人们早就认识到热带气候和变率会受到热带以外地区气候过程的影响。以往关于热带气旋对热带影响的研究基本上是定性的，而且是从完全耦合的海洋-大气角度进行的。因此，热带外气候对热带气候的影响在很大程度上仍未得到探索。该项目的目标是调查热带气候的外部影响，重点是量化热带气候及其变率的外部影响。该项目将使用一种新的建模方法，称为区域耦合数据同化（RCDA）方法，它将耦合数据同化与耦合气候动力学相结合，以评估和了解热带外气候对真实的世界热带气候的影响。在RCDA中，热带外的观测被同化到气候模式中，而热带海洋-大气过程仍然完全耦合。这使得能够定量评估和了解热带气候学和热带气候变异性（如厄尔尼诺/南方涛动）的外部影响。研究小组还将探讨在耦合大气环流模式中热带偏置的外部影响。受资助的研究是对热带气候和热带气候变率的外部影响的系统研究，将耦合数据同化与耦合气候动力学相结合。这项工作将开发一种新的建模策略，以评估和了解热带气候变化对热带气候学和气候变化的影响。这一认识将有助于进一步改进气候模型，用于气候预测、未来气候预测，进而改善其社会影响。该项目将培养两名研究生。

It has long been recognized that tropical climate and variability can be affected by climate processes in the extratropics. Previous studies on the extratropical impact on the tropics have remained largely qualitative in nature and from the fully coupled ocean-atmosphere perspective. As such, the impact of extratropical climate on tropical climate has remained largely unexplored. The goal of this project is to investigate the extratropical impact on tropical climate with the focus on quantifying extratropical influences of tropical climate and its variability. The project will use a novel modeling approach called Regional Coupled Data Assimilation (RCDA) approach, which combines coupled data assimilation with coupled climate dynamics, to assess and understand the extratropical climate impact on tropical climate for the real world. In RCDA, observations in the extratropics are assimilated in climate models while the tropical ocean-atmosphere processes remain fully coupled. This allows the quantitative assessment and understanding of the extratropical impacts on both tropical climatology and tropical climate variability, such as ENSO. The research team will also explore the extratropical impact on the tropical bias in coupled general circulation models. The funded research represents a systematic study of the extratropical impact on tropical climate and tropical climate variability that combines coupled data assimilation with coupled climate dynamics. This work will develop a new modeling strategy to assess and understand the impact of extratropical climate variability on tropical climatology and climate variability. This understanding will help further improve climate models for climate predictions, future climate projections, and, in turn, their societal impacts. This project will train two graduate students.