Lagrangian Scaling and Intermittency of Turbulent CARbon Interface OCean Atmosphere (CARIOCA) Time Series in the Southern Ocean

Abstract In this study, we analyzed a Lagrangian data set composed of observations from 15 CARbon Interface OCean Atmosphere (CARIOCA) drifting buoys deployed in the Southern Ocean. These buoys recorded sea surface temperature (SST), sea surface salinity (SSS), fugacity of , and chlorophyll a fluorescence at a 1‐hr temporal resolution between 2001 and 2012. We investigated the scaling properties of these time series and identified two distinct power‐law spectral regimes, separated by a characteristic timescale of approximately 10 days, likely associated with synoptic‐scale processes. In the high‐frequency regime, SST and SSS exhibited spectral scaling exponents close to 2, consistent with theoretical predictions for three‐dimensional Lagrangian turbulence. For and fluorescence, the mean spectral slopes deviated from 2, with and , respectively, suggesting an influence of biological or biogeochemical activity. Additionally, we detected intermittency in all time series within this regime and estimated a Hurst exponent of and an intermittency coefficient of for , corresponding to a correlated and intermittent random walk. The large‐scale regime, for its part, shows slopes close to 1.3 for all scalars. We further analyzed dependencies between and the other variables using Probability Density Function (PDF) quotient analysis. The results revealed that synoptic‐scale variability plays a key role in governing the interdependence among the variables. Stronger dependencies with SST and SSS were observed at timescales shorter than 10 days, while an asymmetric relationship with fluorescence emerged at longer timescales, likely reflecting primary production processes.