Survey of Tsunamis Formed by Atmospheric Forcing on the East Coast of the United States
Tuesday, 16 December 2014
High-frequency sea level oscillations along the United States East Coast have been linked to atmospheric pressure disturbances observed during large storm events. These oscillations have periods similar to tsunami events generated by earthquakes and submarine landslides, but are created by moving surface pressure anomalies within storm systems such as mesoscale convective systems or mid-latitude cyclones. Meteotsunamis form as in-situ waves, directly underneath a moving surface pressure anomaly. As the pressure disturbances move off the east coast of North America and over the continental shelf in the Atlantic Ocean, Proudman resonance, which is known to enhance the amplitude of the meteotsunami, may occur when the propagation speed of the pressure disturbance is equal to that of the shallow water wave speed. At the continental shelf break, some of the meteotsunami waves are reflected back towards the coast. The events we studied date from 2007 to 2014, most of which were identified using an atmospheric pressure anomaly detection method applied to atmospheric data from two National Data Buoy Center stations: Cape May, New Jersey and Newport, Rhode Island. The coastal tidal records used to observe the meteotsunami amplitudes include Montauk, New York; Atlantic City, New Jersey; and Duck, North Carolina. On average, meteotsunamis ranging from 0.1m to 1m in amplitude occurred roughly twice per month, with meteotsunamis larger than 0.4m occurring approximately 4 times per year, a rate much higher than previously reported. For each event, the amplitude of the recorded pressure disturbance was compared to the meteotsunami amplitude, while radar and bathymetry data were analyzed to observe the influence of Proudman resonance on the reflected meteotsunami waves. In-situ meteotsunami amplitudes showed a direct correlation with the amplitude of pressure disturbances. Meteotsunamis reflected off the continental shelf break were generally higher in amplitude when the average storm speed was closer to that of the shallow water wave speed, which suggests that Proudman resonance has a significant influence on meteotsunami amplitude over the continental shelf. Through the application of these findings the frequency and severity of future meteotsunamis can be better predicted along the east coast of the United States.