Data used in "The Complex Role of Storms in Modulating Air-Sea CO2 Fluxes in the sub-Antarctic Southern Ocean"

The data included in this repository were used to generate the figures for the paper "The Complex Role of Storms in Modulating Air-Sea CO2 Fluxes in the sub-Antarctic Southern Ocean" in Geophysical Research Letter.

Abstract:

"The intra-seasonal CO₂ flux (FCO₂) variability across the Southern Ocean is poorly understood due to sparse observations at the required temporal and spatial scales. Twinned Waveglider-Seaglider experiments were used to investigate how storms influence FCO₂ through both the gas transfer velocity (k_w) and the air-sea gradient in partial pressure of CO₂ (ΔpCO₂) in the sub-Antarctic zone. Winter-spring storms caused ΔpCO₂ to weaken (by 15-55 μatm) due to mixing/entrainment and weaker stratification. This response in ΔpCO₂ was in phase with k_w resulting in a counteractive weakening in FCO₂ (by 6.6 - 26.5% per storm), despite the wind-driven increase in k_w. Stronger stratification during summer explained the weaker sensitivity of ΔpCO₂ to storms, instead its thermal drivers dominated the ΔpCO₂ variability. These results highlight the importance of observing synoptic-scale variability in ΔpCO₂, the absence of which may propagate significant biases to the mean annual FCO₂ estimates from large-scale observing programmes and reconstructions."

The data collected from the Wave Glider, such as the concentration of CO₂ in the atmosphere (xCO_2air) and in the ocean (xCO_2sea), surface temperature and salinity were used to calculate the different parameters of the bulk CO₂ flux formula (FCO₂ = k_w x ko x ΔpCO₂). Note that the meteorological weather station of one of the Wave Gliders was faulty and the wind speed, wind direction and wind stress data was replaced by hourly ERA5 data provided by ECMWF available at https://doi.org/10.24381/cds.bd0915c6. 

The temperature, pressure and salinity data collected by the Seaglider were used to calculate the Mixed Layer Depth and the Brunt Vaisala Frequency of the first 300m of the ocean.