Improving the Resolution of Heat Flux Estimates Across Antarctica Using Recent-Generation Seismic Models

第一部分：地球热通量是全世界重要的地球动力学指标，但在世界上最大的冰盖南极洲的家中尤为重要。冰下热通量强烈地影响着基础冰的温度、冰在其熔点时的体积、液态水的范围和分布、冰床物质的性质、冰下湖泊的形成，以及至关重要的是，冰是冻结还是沿着其与固体地球的界面滑动。最终，它决定了冰盖的热状态和机械稳定性。然而，整个南极洲对冰下热通量的了解仍然很少。在过去的15年里，研究人员采用了各种间接措施来估计南极洲的热通量。拟议的研究旨在通过利用地震模型和热流数据库的最新改进来完善和改进其中一种方法。其目标是提供更好的基础热通量估计及其在南极洲大部分地区的不确定性。如果成功的话，这将是对南极冰盖和冰流建模者的一次重要和及时的升级，并可能影响对全球气候变化和海平面上升在21世纪世纪的影响的评估。第二部分：关于南极冰下热通量的空间扩展信息主要来自间接或代理方法，旨在从固体地球或冰川冰的性质推断热通量。PI过去的工作是基于在地壳和上地幔的全球地震模型指导下在世界其他地方获得的热通量测量值的外推。拟议的工作是更新，完善和扩展的早期方法，旨在解决两个主要挑战：提高大陆尺度的精度和区域尺度分辨率的基础热通量在南极洲的大部分地区。拟议的改进是基于最近在区域尺度地震模型和热流数据库的改进。在过去的几年里，美国、中国、欧洲和加拿大以及南极洲的大部分地区已经开发出了更好的、分辨率更高的地壳和上地幔地震模型，这些模型可以用来指导从美国、中国、欧洲和加拿大向南极洲外推热通量测量。改进方法的关键测试将验证它，以推断地球上存在此类测量的地区的热通量，特别是美国，中国，加拿大和欧洲。这种验证实验将为推断南极洲热通量的拟议方法提供重要的测试，并提供关于推断准确性的定量信息。最后产品将是一张区域尺度的热通量图，并附有南极洲中部和西部的不确定性信息。该地图将由提议的南极洲中部和西部热通量分布的平均值和标准差组成，网格间距约为100公里。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Part I: Non-TechnicalGeothermal heat flux is an important geodynamic indicator throughout the world but is uniquely important in the home of the world’s largest ice cap, Antarctica. Subglacial heat flux strongly influences basal ice temperatures, the volume of ice at its melting point, the extent and distribution of liquid water, the properties of glacial bed material, the formation of subglacial lakes, and, crucially, whether the ice is frozen to or slides along its interface with the solid earth. Ultimately, it determines the thermal state and mechanical stability of the ice sheet. Nevertheless, subglacial heat flux remains poorly known across Antarctica. Over the past 15 years, researchers have introduced a variety of indirect measures to estimate heat flux across Antarctica. The proposed research aims to refine and improve one of these methods by leveraging recent improvements in seismic models and heat flow data bases. The goal is to deliver better basal heat flux estimates and their uncertainties across much of Antarctica. If successful, this promises to be an important and timely upgrade for Antarctic ice-sheet and ice-stream modelers and may affect the assessment of the impact of global climate change and sea level rise in the 21st century. Part II: TechnicalSpatially extended information about subglacial heat flux across Antarctica derives mainly from indirect or proxy methods that aim to infer heat flux from properties of the solid earth or glacial ice. Past work by the PI has been based on the extrapolation of heat flux measurements obtained elsewhere in the world guided by a global seismic model of the crust and upper mantle. The proposed work is an update, refinement, and extension of the earlier method designed to address two principal challenges: improving continental-scale accuracy and regional-scale resolution of basal heat flux across a large fraction of Antarctica. The proposed refinements are based on recent improvements in regional-scale seismic models and heat flow data bases. Better and notably higher-resolution seismic models of the crust and uppermost mantle have been developed in the past few years across the US, China, Europe, and Canada, as well as across much of Antarctica, that can be used to guide the extrapolation of heat flux measurements to Antarctica from the US, China, Europe, and Canada. The critical test for the refined method will be validating it to infer heat flux across regions of the earth where such measurements exist, notably the US, China, Canada, and Europe. Such validation experiments will provide crucial tests of the proposed methods to infer heat flux across Antarctica as well as quantitative information about the accuracy of the inferences. The final product will be a regional-scale heat flux map with attendant uncertainty information across central and West Antarctica. The map will be composed of the means and standard deviations of the proposed inferred heat flux distributions across central and western Antarctica with a grid-spacing of about 100 km.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.