Observed ocean thermal response to Hurricanes Gustav and Ike

• Published in: Journal of geophysical research. Oceans 2016-01, Vol.121 (1), p.162-179
• Main Authors: Meyers, Patrick C., Shay, Lynn K., Brewster, Jodi K., Jaimes, Benjamin
• Format: Article
• Language: English
• Subjects: Anomalies; AXBTs; Bathythermographs; Drift; Drifters; Eddy currents; Ekman pumping; Enthalpy; Entrainment; Estimates; field campaign; Geophysics; Heat content; Height anomalies; Hurricanes; In situ measurement; Isotherms; Loop Current; Marine; Mixed layer; ocean heat content; Ocean mixed layer; Oceans; satellite technique validation; Satellites; Sea surface; Sea surface temperature; Storms; Surface temperature; Temperature (air-sea); Thermal response; Thermal structure; Thermocline; Upper ocean; Variation; Wind; XBTs
• ISSN: 2169-9275; 2169-9291
• DOI: 10.1002/2015JC010912

The 2008 Atlantic hurricane season featured two hurricanes, Gustav and Ike, crossing the Gulf of Mexico (GOM) within a 2 week period. Over 400 airborne expendable bathythermographs (AXBTs) were deployed in a GOM field campaign before, during, and after the passage of Gustav and Ike to measure the evolving upper ocean thermal structure. AXBT and drifter deployments specifically targeted the Loop Current (LC) complex, which was undergoing an eddy‐shedding event during the field campaign. Hurricane Gustav forced a 50 m deepening of the ocean mixed layer (OML), dramatically altering the prestorm ocean conditions for Hurricane Ike. Wind‐forced entrainment of colder thermocline water into the OML caused sea surface temperatures to cool by over 5°C in GOM common water, but only 1–2°C in the LC complex. Ekman pumping and a near‐inertial wake were identified by fluctuations in the 20°C isotherm field observed by AXBTs and drifters following Hurricane Ike. Satellite estimates of the 20° and 26°C isotherm depths and ocean heat content were derived using a two‐layer model driven by sea surface height anomalies. Generally, the satellite estimates correctly characterized prestorm conditions, but the two‐layer model inherently could not resolve wind‐forced mixing of the OML. This study highlights the importance of a coordinated satellite and in situ measurement strategy to accurately characterize the ocean state before, during, and after hurricane passage, particularly in the case of two consecutive storms traveling through the same domain. Key Points: Ocean response to two hurricanes were observed during a 2008 field campaign Satellite methods accurately measured prestorm ocean heat content The near‐inertial response could not be captured by the two‐layer model