Global Observations of the Response of the Upper Ocean to Tropical Cyclones Based on Argo Profiles

The upper ocean's temperature and salinity responses to Tropical Cyclones (TC) between 10˚—30° latitude on both sides of the Equator are observed with Argo float profile pairs between 2001 and 2024. The ocean response is found using across-track composites, generated by normalizing the distance between the profile and cyclone track by the 34-knot wind radius (R₃₄) of each TC. Cooling of up to 1.2°C in the initial mixed layer (ML) extends from the TC center to about 3 R₃₄ and is stronger on the side of the TC track with stronger winds. Subsurface warming between 40 and 80 m depth is observed between 0.5 and 3 R₃₄ on the side of the track with stronger winds. Strong cooling is observed in a distinct core directly under the TC path (between ±0.5 R₃₄), reaching from the surface to 1,000 m depth with upward isopycnal displacements of up to 18 m. Surface cooling and subsurface warming at the base of the ML are positively correlated with TC wind stress on the ocean, quantified by the Local Wind Power Dissipation index (PDi_L), and negatively correlated with the energy required to destratify the upper ocean, defined by the Cooling Inhibition index (CI). Subsurface warming is common with low CI but is not observed with high CI. The typical cross-track thermal response between 30 and 150 m depth is heat loss, but the subsurface ocean can gain heat in low CI cases.