Importance of Orography for Greenland cloud and melt response to atmospheric blocking
Ummenhofer, Caroline C.
MetadataShow full item record
More frequent high pressure conditions associated with atmospheric blocking episodes over Greenland in recent decades have been suggested to enhance melt through large-scale subsidence and cloud dissipation, which allows more solar radiation to reach the ice sheet surface. Here we investigate mechanisms linking high pressure circulation anomalies to Greenland cloud changes and resulting cloud radiative effects, with a focus on the previously neglected role of topography. Using reanalysis and satellite data in addition to a regional climate model, we show that anticyclonic circulation anomalies over Greenland during recent extreme blocking summers produce cloud changes dependent on orographic lift and descent. The resulting increased cloud cover over northern Greenland promotes surface longwave warming, while reduced cloud cover in southern and marginal Greenland favors surface shortwave warming. Comparison with an idealized model simulation with flattened topography reveals that orographic effects were necessary to produce area-averaged decreasing cloud cover since the mid-1990s and the extreme melt observed in the summer of 2012. This demonstrates a key role for Greenland topography in mediating the cloud and melt response to large-scale circulation variability. These results suggest that future melt will depend on the pattern of circulation anomalies as well as the shape of the Greenland Ice Sheet.
Author Posting. © American Meteorological Society, 2020. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Hahn, L. C., Storelvmo, T., Hofer, S., Parfitt, R., & Ummenhofer, C. C. Importance of Orography for Greenland cloud and melt response to atmospheric blocking. Journal of Climate, 33(10), (2020): 4187-4206, doi:10.1175/JCLI-D-19-0527.1.
Suggested CitationHahn, L. C., Storelvmo, T., Hofer, S., Parfitt, R., & Ummenhofer, C. C. (2020). Importance of Orography for Greenland cloud and melt response to atmospheric blocking. Journal of Climate, 33(10), 4187-4206.
Showing items related by title, author, creator and subject.
Kwon, Young-Oh; Seo, Hyodae; Ummenhofer, Caroline C.; Joyce, Terrence M. (American Meteorological Society, 2019-12-31)Recent studies have suggested that coherent multidecadal variability exists between North Atlantic atmospheric blocking frequency and the Atlantic multidecadal variability (AMV). However, the role of AMV in modulating ...
Blocking statistics in a varying climate: Lessons from a "traffic jam" model with pseudostochastic forcing Paradise, Adiv; Rocha, Cesar B.; Barpanda, Pragallva; Nakamura, Noboru (American Meteorological Society, 2019-09-12)Recently Nakamura and Huang proposed a semiempirical, one-dimensional model of atmospheric blocking based on the observed budget of local wave activity in the boreal winter. The model dynamics is akin to that of traffic ...
Stratus Ocean Reference Station (20˚S, 85˚W), mooring recovery and deployment cruise R/V Revelle cruise dana 03, November 10 - November 26, 2003 Hutto, Lara; Weller, Robert A.; Lord, Jeffrey; Smith, Jason C.; Ryder, James R.; Galbraith, Nancy R.; Fairall, Christopher W.; Stalin, Scott; Andueza, Juan Carlos; Tomlinson, Jason (Woods Hole Oceanographic Institution, 2004-03)The Ocean Reference Station at 20°S, 85°W under the stratus clouds west of northern Chile and Peru is being maintained to provide ongoing, climate-quality records of surface meteorology, of air-sea fluxes of heat, ...