Statistical Analysis of Spatiotemporal Variations of Air‐Sea CO2 Fluxes in the Kuroshio Region

Abstract

AbstractSpatiotemporal variations in air‐sea CO2 fluxes in the Kuroshio region were evaluated using measurements made by voluntary cargo ships and research vessels. The data were re‐gridded to produce a 1° × 1° horizontal grid and 0.1‐year timesteps. Spatial clustering showed that the area north of approximately 30°N was the strongest atmospheric CO2 sink. The spatial differences were largest in winter and insignificant in summer. The oceanic CO2 uptake in the Kuroshio region increased from 2000 to 2019. Changes in the wind speed and total alkalinity affected the decadal increase in CO2 absorption. The spatial distributions of the air‐sea CO2 fluxes were affected by the Kuroshio large meander (KLM). This effect was likely caused by the change in seawater fCO2 via the change in the Kuroshio Extension Path during the KLM period. The Fourier regression technique used in the data analysis was expected to facilitate analyses of the carbonate system in coastal waters, where comprehensive on‐site measurements and satellite analyses are difficult.