Arrested development of a tropical cyclone: Measurements from a profiling float array

Shaun Johnston1, Daniel L Rudnick1, Jim Moum2 and Noel Brizuela3, (1)Scripps Institution of Oceanography, La Jolla, CA, United States, (2)Oregon State Univ, Corvallis, OR, United States, (3)University of California San Diego, Scripps Institution of Oceanography, La Jolla, CA, United States
For $>$2 months, a float array obtained $>$20,000 temperature profiles from the surface to 80--200 m every 25--40 minutes before, during, and after Super Typhoons (STY) Mangkhut, Trami, Kong-Rey, and Yutu. One float was within Mangkhut's eye (21 km from the centre), another float approached within 46 km, and 4 (2) other floats were within the radius of storm (gale) force winds. Mangkhut caused mixed layer temperatures/heat content to decrease $>$1$^\circ$C / 200 MJ m$^{-2}$. Further cooling during Trami and Kong-Rey was observed. With 3 STY over 3 weeks, the upper ocean took 5--7 weeks to recover its pre-Mangkhut heat content. The 2 floats closest to Mangkhut tracked cool, subsurface water in the North Equatorial Current (NEC) from 1200--2000 km over the next 6 weeks. Sea surface temperature maps, covering a wider area than the floats measured, also show the cool wake propagated westward in the NEC. This persistent subsurface cool water likely contributed to STY Yutu's downgrade to typhoon before landfall.