Before PIRATA, no microstructure measurements had been conducted in the open tropical Atlantic. PIRATA service cruises between 2005 and 2010 provided the first direct observations of turbulent mixing, revealing strong equatorial enhancement of vertical cooling linked to vertical shear (Hummels et al., 2013, 2014; Wenegrat & McPhaden, 2015). These studies quantified seasonal and regional variability of diapycnal fluxes, showing maximum turbulent cooling during boreal summer and allowing closure of the mixed-layer heat budget at 10°W. Findings confirmed model results and highlighted the role of turbulence in controlling SST, SSS, and nutrient supply, similar to the Pacific (Lien et al., 2008; Moum et al., 2013). Since 2014, chipods deployed on PIRATA moorings have provided continuous time series of upper ocean mixing, establishing PIRATA as a key source of long-term turbulence observations in the tropical Atlantic (Moum et al., 2022, 2023).
