Wave Glider-based Measurements and Corrections of Near-surface pCO2
Gradients in the Coastal Ocean
Abstract
Carbonate system dynamics are highly variable in coastal and shelf
regions, and poor spatiotemporal measurement resolution leads to
inadequate constraints for global carbon sequestration estimates.
Additionally, conventional pCO2 measurement-based flux calculations
require an assumption of homogeneity in near-surface waters and an
isometric temperature correction that excludes effects such as
biological drivers and air-sea disequilibrium. To quantify the effect of
these drivers, by capturing high resolution measurements during
short-term events, we present the deployment of a Liquid Robotics Wave
Glider equipped with mirrored gas sensor suites at surface and
subsurface during the 2022 spring bloom on the Scotian Shelf in eastern
Canada. The temporal variability in the data reveals biologically driven
diurnal pCO2 behavior that conventional, low-resolution methods may
overlook. Additionally, through direct measurement of surface and
sub-surface pCO2 levels we demonstrate that conventional underway
measurement methods systematically underestimate surface pCO2 values in
this region by 1 – 10 µatm, leading to flux estimation errors of up to
7%. These findings emphasize the value of high-resolution data for
determining drivers of spatial variability and question the capacity of
underway lines to measure true surface pCO2 values. By employing
vehicle-based measurement techniques we can improve our understanding of
carbon dynamics in coastal environments and refine flux estimates for
accurate climate modeling and management strategies.