Collaborative Research: Atmospheric controls of moisture extremes over Greenland

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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.