Sea surface temperature pattern influence on monsoon variability and change

气候变化可能会增加季风降雨量，但会导致更大的变异性和极端情况。然而，全球气候模式(GCM)对热带海面温度(SSTs)的增暖模式以及季风降水的区域变化存在分歧。GCM对当前气候中的季风风和降雨量也有很大的偏差，这增加了它们对未来气候预测的不确定性，尽管它们在很大程度上捕捉到了不同大陆季风强度的相对差异。为了解释气候模型预测，我们需要对季风如何响应不同的SST模式有一个基于物理的理解。以前的研究经常将亚洲季风的相对强度和可靠性(与非洲或北美/南美季风相比)归因于大陆区域、地形或急流或波浪相互作用的动力强迫的差异。该项目将调查诸如印度-太平洋暖池等海温不对称对季风强度的影响。假设是，赤道外某些热带陆地地区较暖的上风海温在增强相应季风的相对强度方面起主导作用，因为它们提供的湿气和近地表湿静态能量允许更多的降雨和更强的季风环流。主要问题：1.纬向海温不对称如何影响不同区域和大陆的季风相对强度？2.气候预测中海温变暖的不同模式对潜在的区域季风变化有什么影响？3.我们能否利用20世纪海温变化的观测模式来告知或约束未来对区域季风的预测？对于这个PHD项目，学生将进行研究，以提高我们对季风降雨如何与水汽来源相互作用以及季风未来可能发生变化的理解。这项工作将涉及进行和分析全球气候模型实验，包括最先进的高分辨率过程模型模拟以及观测和更高分辨率的模拟。这名学生将与埃克塞特气象局的科学家们密切合作，无论是远程访问还是面对面访问。

Climate change will likely increase monsoon rainfall but lead to greater variability and extremes. However, global climate models (GCMs) disagree on the warming pattern of tropical sea surface temperatures (SSTs) as well as regional changes in monsoon rainfall. GCMs also have large biases in monsoon winds and rainfall in the present climate, which increases uncertainty in their climate projections for the future, although they largely capture relative differences in monsoon strength across different continents. To interpret climate model projections, we need a physically based understanding of how monsoons respond to different SST patterns. Previous studies often attributed the relative strength and reliability of the Asian monsoon (compared to African or North/South American monsoons) to differences in continental area, orography, or dynamical forcing from jet or wave interactions. This project will investigate the effects of SST asymmetries such as the Indo-Pacific warm pool on monsoon strength. The hypothesis is that warmer SSTs upwind of certain off-equatorial tropical land regions play a dominant role in increasing the relative strength of a corresponding monsoon because of the moisture and near-surface moist static energy that they supply, which allows for more rainfall and a stronger monsoon circulation.Main questions: 1. How do zonal SST asymmetries affect the relative strength of monsoons in different regions and continents? 2. What implications do different patterns of SST warming in climate projections have for potential regional monsoon changes?3. Can we use observed patterns of 20th-century SST change to inform or constrain future projections of regional monsoons?For this PhD project, the student will undertake research that will lead to improvements in our understanding of how monsoon rainfall interacts with moisture sources and how monsoons might change in the future. The work will involve performing and analysing global climate model experiments, including state-of-the-art of high-resolution process model simulations as well as observations and coarser-resolution simulations. The student will work closely with scientists at the Met Office in Exeter, both remotely and during in-person visits.