Quantifying the Impact of Atmospheric Blocking on the Mean State of the North Atlantic Sector of the Arctic

Recent changes in low-frequency atmospheric circulation in the North Atlantic sector of the Arctic (NAA) have increased sensible heat and moisture advection from the mid-latitudes into this region. This, in turn, has altered the surface energy budget over the Greenland Ice Sheet and adjacent sea ice and contributed to unprecedented melt and freshwater runoff events, as was evident on 08 July 2012 where approximately 40% of the ice sheet's surface had experienced melt. These extreme events have significant and yet unexplored impacts on DoD infrastructure and operations in the NAA. Motivated by such extreme events, we seek to understand and quantify how atmospheric blocking and Rossby wave breaking impact, and are impacted by, the transport of moisture from mid-latitudes into the NAA

This study presents initial findings towards this research objective, via application of a moisture transport and blocking climatology (1980-present) in the NAA region. To ensure a robust result, an ensemble approach using multiple high-quality atmospheric reanalysis products, including NCEP CFSR, ERA-Interim/ERA5, and NASA MERRA-2, is used to identify blocking events. Metrics of moisture transport will include integrated water vapor and vertically integrated horizontal water vapor. Preliminary results will be discussed first using one reanalysis product, then extended to the others.