Analysis of the Seasonal and Interannual Variations of Air‐Sea CO₂ Flux in the Chukchi Sea Using a Coupled Ocean‐Sea Ice‐Biogeochemical Model

Abstract

Understanding the responses of air‐sea carbon dioxide (CO2) flux to rapid environmental changes in the highly productive Chukchi Sea is of great significance for the climate prediction in the Arctic Ocean. Through analyzing the 1998–2015 hindcast simulation of a coupled ocean–sea ice–biogeochemical model, this study identifies that the key factors influencing oceanic carbon uptake in the Chukchi Sea vary seasonally. The effects of these seasonal carbon uptakes on the total annual carbon sink vary at different timescales. The model solution suggests that the Chukchi Sea acts as a perennial carbon sink of atmospheric CO2 with the annual mean influx of −3.73 ± 3.90 mmol m−2 d−1. Quantitative analyses reveal that the sea ice concentration predominates the annual cycle of air‐sea CO2 flux, while primary production and wind speed strengthen the capacity for carbon uptake during June–July (melt season) and October–December (freeze season), respectively. The total annual carbon sink shows an increasing trend during 1998–2015 with a multi‐year average of 9.22 ± 1.93 Tg C y−1. The carbon uptakes during June–July and August–September (open water season), which are respectively regulated by primary production and open water area at interannual scale, present significant long‐term increases and jointly determine the secular increase trend of the total annual carbon sink. Interannual CO2 absorption during the freeze season is sensitive to the sea ice concentration and wind conditions, presenting the greatest year‐to‐year variation but insignificant long‐term trend, and modulates the interannual amplitude of the total annual carbon sink.

RETRACTED: Rapid Acidification of the Arctic Chukchi Sea Waters Driven by Anthropogenic Forcing and Biological Carbon Recycling

“…As a result, the cumulative changes from thermal and non‐thermal components in pH and Ω arag are −0.0035 years −1 and −0.0106 years −1 , respectively, which are consistent with the observed long‐term OA trends (accounting for 103% ± 11% for pH and 121% ± 36% for Ω arag ) (Figure 4). In the ACW, the CO 2 sink has increased over the past two decades (Tu et al., 2021; Zheng et al., 2021). The increased vertical flux and respiration of organic matter below the pycnocline introduces more additional CO 2 into the subsurface CSW and PWW waters (aerobic respiration; Stabeno et al., 2018), thereby decreasing pH and Ω arag and enhancing subsurface and near‐bottom acidification over the past 17 years.…”

Spatiotemporal distributions of air-sea CO2 flux modulated by windseas in the Southern Indian Ocean

“…SSS is a product of the NCEP Global Ocean Data Assimilation System, which is forced by the momentum flux, heat flux, and fresh water flux from the NCEP atmospheric reanalysis (GODAS, Behringer et al, 1998). It reproduces observations well and is now the most commonly used dataset for F analysis (e.g., Watson et al, 2020;Monteiro et al, 2020;Zheng et al, 2021). For the DpCO 2 , we employed the observationbased global monthly gridded atmospheric and sea surface CO 2 partial pressure and CO 2 fluxes product by Landschützer et al (2020) from 1982 onwards.…”

Early Wintertime CO2 Uptake in the Western Arctic Ocean

“…Zheng et al. (2021) have found that these factors also control interannual variations of the CO 2 flux but in ways that differ seasonally. Wang et al.…”

“…The reduction of the CO 2 sink in the Chukchi Sea resulted in a relatively small CO 2 sink of the Arctic Ocean in 2012, although the year 2012 recorded an extreme sea-ice loss. Zheng et al (2021) have scrutinized seasonal and interannual variations of the air-sea flux of CO 2 in the Chukchi Sea using outputs from a coupled ocean-sea ice biogeochemical model. The results have demonstrated that the annual cycle of the air-sea flux of CO 2 is regulated primarily by the concentration of sea ice and that primary production and wind speed are crucial to CO 2 uptake in June-July and October-December, respectively.…”

“…The results have demonstrated that the annual cycle of the air-sea flux of CO 2 is regulated primarily by the concentration of sea ice and that primary production and wind speed are crucial to CO 2 uptake in June-July and October-December, respectively. Zheng et al (2021) have found that these factors also control interannual variations of the CO 2 flux but in ways that differ seasonally. Wang et al (2022) have examined summer surface-water CO 2 dynamics in the Bering Sea and Chukchi Shelf using SOCAT fCO 2 and fCO 2 data collected by unmanned surface vehicles.…”