Seasonal and Regional Variations in Arctic Blocking Patterns

Authors: Haylie Mikulak*, University of Georgia, Thomas Mote, University of Georgia, Gina Henderson, United States Naval Academy, Bradford Barrett, United States Naval Academy
Topics: Cryosphere, Climatology and Meteorology, Polar Regions
Keywords: Arctic, Atmospheric Blocking Patterns
Session Type: Guided Poster
Day: 4/4/2019
Start / End Time: 1:10 PM / 2:50 PM
Room: Roosevelt 3.5, Marriott, Exhibition Level
Presentation File: Download

Atmospheric blocking patterns are “quasi-stationary”, large-scale circulation patterns lasting 10-20 days. There are four main regions for blocking in the Northern Hemisphere – North Pacific, Greenland, Europe, and Ural-Siberian – which influence the weather and climate of the Arctic as well as the lower latitudes through sensible and latent heat advection. The advection of heat into the Arctic, in turn, has broader implications, including increased rates of surface melt for snow cover, sea ice, and land ice, including the Greenland ice sheet. Blocking events can be identified using indices based on different atmospheric fields including geopotential height and potential temperature on a constant potential vorticity surface. However, recent research has identified significant differences stemming from the different indices used. This study develops a further understanding of blocking pattern frequency in the Arctic, both spatially and temporally, by comparing two distinct blocking indices. With the use of ERA-Interim reanalysis data, the adjusted Tibaldi and Molteni (1990) index is compared with the Pelly and Hoskins (2003) index to construct a climatology of blocking frequency for four quadrants of the Arctic during all four seasons. Previous findings show that during winter, blocking frequency is greatest over the eastern Atlantic and Europe, while summer blocking frequency is greatest over eastern Europe and central Asia. However, few studies have neither examined the frequency of blocking during the transition seasons, nor examined these features with more than one index, which can be vital for better understanding the relationship between blocking and surface melt.

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