The Climatology of Storm Surge-Producing Extratropical Cyclones in Observations and Models

Strong coastal storms can devastate heavily populated areas by producing powerful winds that can create a large storm surge. Both tropical and extratropical cyclones (ETCs) over the northwestern Atlantic Ocean can produce such storm surges at locations in the northeastern United States.  At The Battery in New York City, 17 of the 20 largest storm surge events were a consequence of ETCs, which are more prevalent than tropical cyclones in this region.  We analyze the climatology of surge-producing ETCs along the northeastern coast of the United States.  For a historical analysis, water level data were collected from National Oceanic and Atmospheric Administration (NOAA) tide gauges at three separate locations (Sewell’s Pt., VA, The Battery, NY, and Boston, MA).  We perform a k-means cluster analysis of sea level pressure from the ECMWF 20^th Century Reanalysis dataset (ERA-20c) to explore the natural sets of observed storms with similar characteristics. We then composite cluster results with features of atmospheric circulation to observe the influence of large-scale climate teleconnections such as the North Atlantic Oscillation.  Because extreme surge-producing ETC events are rare in the modern observational record, long simulations with global climate models provide an opportunity to examine a much larger sample of extreme events.  To investigate the suitability of this approach, the capability of a high-resolution coupled climate model to realistically simulate such events will also be assessed.  We employ a tracking algorithm to identify ETCs in a multi-century simulation and compare the spatial and temporal distributions  of cyclolysis, cyclogenesis, and cyclone densities from the model to various reanalysis products.