Collaborative Research: Atmospheric controls of moisture extremes over Greenland

至少自1979年以来，格陵兰经历了北极地区夏季大气变暖和增湿趋势最大的一些地区。观测到的格陵兰上空气温和大气水分含量的增加对该区域的气候有重大影响。这些变化改变了格陵兰冰盖上降水的频率、类型和总量，增加了极端热浪和融化事件的可能性，这些事件直接影响该地区及其周围的海和陆地冰的增长和损失率。尽管格陵兰岛顶部显著变暖和增湿，但最近这些趋势背后的驱动机制却鲜为人知。到目前为止，关于当地海洋和大气过程、气候系统中更广泛的尺度机制或这些多尺度因素的组合是否可归因于与格陵兰变暖和增湿有关的大气环流模式的维持，研究尚未得出结论。更全面地了解这些复杂的气候系统相互作用，对于改进气候模型物理，更准确地捕捉格陵兰冰盖变化和由此产生的全球影响，如海平面上升，是至关重要的。该项目的总体假设是，低频、高纬度环流变化对多种过程敏感，包括人为、偏远和本地气候强迫。通过对社区地球系统模式(CESM)第1版和第2版的历史、大气数据和气候模式实验以及耦合模式对比项目(CMIP6)第6阶段的模式输出的统计和诊断分析，该项目将严格检验这一假设，同时解决格陵兰水气候研究中的几个知识空白，主要由三个问题指导：1)与当地海洋-大气过程有关的自然气候和人为强迫是格陵兰地区夏季环流变率以及年际到年代际时间尺度上气温和湿度的最强控制因素？2)大尺度环流变率及其相关过程如何调节格陵兰地区天气到季节平均时间尺度的湿度？3)CESM2和CMIP6模式在复制格陵兰上空观测到的环流变化及其对温度和湿度的相关影响方面的可靠性如何？项目成果将通过开发格陵兰各地水分过程的近乎实时的在线可视化，以及组织关于格陵兰周围的大气、海洋和冰冻圈相互作用的工作组或混合研讨会与科学界和公众共享。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。

Greenland has experienced some of the largest summertime atmospheric warming and moistening trends of any region within the Arctic since at least 1979. The observed increases in air temperatures and atmospheric moisture content over Greenland have significant implications for the region’s climate. These changes have altered the frequency, type, and total amount of precipitation falling on the Greenland Ice Sheet and increased the likelihood of extreme heatwaves and melt events that directly affect sea and land ice growth and loss rates in and around the region. Despite the notable warming and moistening atop Greenland, the driving mechanisms behind these recent trends are poorly understood. Research to date has been inconclusive on whether local oceanic and atmospheric processes, broader-scale mechanisms in the climate system, or a combination of these multiscale factors are attributable to sustaining the atmospheric circulation patterns associated with Greenland’s warming and moistening. A more complete understanding of these complex climate system interactions is essential to improving climate model physics and more accurately capturing Greenland’s ice sheet changes and resulting global impacts, like sea-level rise.The overarching hypothesis for this project is that low frequency, high-latitude circulation variability is sensitive to multiple processes, including anthropogenic, remote, and local climate forcings. Through statistical and diagnostic analyses of historical, atmospheric data, and climate model experiments from the Community Earth System Model (CESM) version 1 and 2 and model output from phase 6 of the Coupled Model Intercomparison Project (CMIP6), the project will rigorously test this hypothesis while addressing several knowledge gaps in Greenland hydroclimate research guided by three main questions: 1) what natural climate and anthropogenic forcings associated with local ocean-atmosphere processes are the strongest controls of the Greenland region’s summer circulation variability and air temperature and moisture on interannual-to-interdecadal time scales?; 2) how do large-scale circulation variability and associated processes regulate weather-to-seasonal mean time scale moisture over the Greenland region?; and 3) how reliable are CESM2 and CMIP6 models in replicating observed circulation changes over Greenland and associated impacts on temperature and moisture? Project outcomes will be shared with the scientific community and the public through development of near-real time online visualizations of moisture processes across Greenland and the organization of a working group or hybrid workshop on atmosphere, ocean, and cryosphere interactions around Greenland.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.