An Historical Perspective of Loop Activity from Nov. 2014 to Oct. 2015

Abstract

This paper compares the Loop activity during a one-year period beginning November 1, 2014 to the historical record derived from the Gulf Eddy Model (GEM) which covers 27 yrs. During our Study period, five anticyclones were generated (Lazarus, Michael, Nautilus I, Nautilus II, and Olympus) or one eddy every two months, far exceeding the 10-month shedding frequency observed in the historical data. Histograms describing the percent occurrence and intensity of ocean currents observed over the Study period are compared to historical statistics at sites in Walker Ridge, Mississippi Canyon, and Green Canyon and show Loop or Eddy (LCE) currents occurred at roughly twice the average historical frequency. At the two sites in Walker Ridge, the peak observed speed was near the 100-yr extreme calculated from GEM. At the Shell Stones site, observed currents exceeded the 100-yr GEM calculation by about 10% when the site was impacted by the combined currents of the Loop and a strong associated cyclone. GEM does not include cyclones so it is not too surprising that it could underestimate the currents in these situations.