A three-year investigation of Greenland's influence on the atmospheric circulation of the North Atlantic region is proposed. Observational analyses and mesoscale simulations will examine the impact of extremes of the North Atlantic Oscillation (NAO) on Greenland cyclonic activity and describe the casual mechanisms. In particular, the influences of Greenland topography including the role of the katabatic winds are evaluated. The observational analyses will provide details on cyclone climatology in this important, yet little-studied, region. The mesoscale numerical model to be used is the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model version 5 (MM5) modified for ice sheet meteorology. The numerical study will be divided into two parts: a moderately high resolution set of seasonal simulations to produce detailed statistics for both phases of the NAO, and a set of very high resolution simulations of representative cyclonic events to better understand their dynamics.
