Wintertime Atmospheric Circulation near Southern Greenland

The high topography of Greenland (> 3,000 m) plays a critical role in the atmospheric patterns affecting the western North Atlantic Ocean. In a broad-scale sense the orography of Greenland influences the Icelandic low (e.g. Kristjansson and McInnes 1999; Petersen et al. 2004) and the associated North Atlantic Oscillation, which in turn impacts the state of the sub-polar gyre and its interannual variability (e.g. Dickson et al. 1996; Häkkinen and Rhines 2004). On smaller scales, the topography of Greenland exerts an enormous influence on local weather systems and on the passage of individual storms (e.g. Cappelen et al. 2001; Doyle and Shapiro 1999). Recent advances from improved atmospheric mesoscale models (e.g. MM5, HIRLAM) and high-resolution observations (QuikSCAT) have offered new glimpses into the structure and dynamics of these features. In wintertime, several distinct atmospheric patterns dominate, each of them associated with strong low level winds (>20 m s-1) over different parts of the western Irminger Sea and eastern Labrador Sea. Here we limit the discussion of these patterns to the region near Cape Farewell. One should keep in mind that the length scales of the features in question (often as small as tens of kilometers) make them difficult to detect in the relatively low-resolution global meteorological analyses (e.g. from NCEP or ECMWF). At the same time, proper representation of these features and the associated air-sea heat transfer can be important for short- and medium-term weather prediction. Sensitivity analyses often indicate that the specification of the initial conditions in this region can exert a significant impact on the subsequent forecast.

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