Air–sea CO<sub>2</sub> flux in the Pacific Ocean for the period 1990–2009

Abstract

Abstract. Air-sea CO 2 fluxes over the Pacific Ocean are known to be characterized by coherent large-scale structures that reflect not only ocean subduction and upwelling patterns, but also the combined effects of wind-driven gas exchange and biology. On the largest scales, a large net CO 2 influx into the extratropics is associated with a robust seasonal cycle, and a large net CO 2 efflux from the tropics is associated with substantial interannual variability. In this work, we have synthesized estimates of the net air-sea CO 2 flux from a variety of products, drawing upon a variety of approaches in three sub-basins of the Pacific Ocean, i.e., the North Pacific extratropics • N), the tropical Pacific (18 • S-18 • N), and the South Pacific extratropics (44.5-18 • S). These approaches include those based on the measurements of CO 2 partial pressure in surface seawater (pCO 2 sw), inversions of ocean-interior CO 2 data, forward ocean biogeochemistry models embedded in the ocean general circulation models (OBGCMs), a model with assimilation of pCO 2 sw data, and inversions of atmospheric CO 2 measurements. Long-term means, interannual variations and mean seasonal variations of the regionally integrated fluxes were compared in each of the sub-basins over the last two decades, spanning the period from 1990 through 2009. A simple average of the long-term mean fluxes obtained with surface water pCO 2 diagnostics and those obtained with ocean-interior CO 2 inversions are −0.47 ± 0.13 Pg C yr the North Pacific extratropics, +0.44 ± 0.14 Pg C yr −1 in the tropical Pacific, and −0.37 ± 0.08 Pg C yr −1 in the South Pacific extratropics, where positive fluxes are into the atmosphere. This suggests that approximately half of the CO 2 taken up over the North and South Pacific extratropics is released back to the atmosphere from the tropical Pacific. These estimates of the regional fluxes are also supported by the estimates from OBGCMs after adding the riverine CO 2 flux, i.e., −0.49 ± 0.02 Pg C yr −1 in the North Pacific extratropics, +0.41 ± 0.05 Pg C yr −1 in the tropical Pacific, and −0.39 ± 0.11 Pg C yr −1 in the South Pacific extratropics. The estimates from the atmospheric CO 2 inversions show large variations amongst different inversion systems, but their median fluxes are consistent with the estimates from climatological pCO 2 sw data and pCO 2 sw diagnostics. In the South Pacific extratropics, where CO 2 variations in the surface and ocean interior are severely undersampled, the difference in the air-sea CO 2 flux estimates between the diagnostic models and ocean-interior CO 2 inversions is larger (0.18 Pg C yr −1 ). The range of estimates from forward OBGCMs is also large (−0.19 to −0.72 Pg C yr −1 ). Regarding interannual variability of air-sea CO 2 fluxes, positive and negative anomalies are evident in the tropical Pacific during the cold and warm events of the El Niño-Southern Oscillation in the estimates from pCO 2 sw diagnostic models and from OBGCMs. They are consistent in phase with the Southern Oscillation In...

Anthropogenic CO2 uptake, transport, storage, and dynamical controls in the ocean imposed by the meridional overturning circulation: A modeling study

“…Subdomain boundaries follow the domain decomposition specified by the Regional Carbon Cycle Assessment and Processes (RECCAP) [Canadell et al, 2011] of the Global Carbon Project (black lines in Figure 1 and Table 1). Accordingly, in terms of transport, this study also complements the Pacific synthesis study of Ishii et al [2014] (which served as the Pacific component of the RECCAP project). In the 11-layer coarse graining, examining the impact of STCs on mode waters in the subtropical North Pacific is achieved by further dividing this region into northern and southern domains.…”

“…In addition to the mean value between 1990 and 2007, the standard deviation of the interannual variability is provided as a measure of uncertainty. The period 1990-2007 corresponds to the period considered by Ishii et al [2014]. The robustness of the monthly mean diagnostics is tested through a comparison with those calculated using 5 day means throughout the year 1990.…”

Trends in pCO2 and sea–air CO2 flux over the global open oceans for the last two decades

“…In addition, various products of wind field are available from reanalysis today, and it is usually the case that different wind fields are used with different pCO 2 s algorithms to evaluate a gas transfer velocity across the sea-air interface and then sea-air CO 2 flux. It is therefore important that we quantify how different wind-field products used to calculate the gas transfer velocity give different estimates of sea-air CO 2 flux (e.g., Ishii et al 2014).…”

Ion association in water solution of soil and vadose zone of chestnut saline solonetz as a driver of terrestrial carbon sink

“…Modern non-thermodynamic techniques are used for modeling the associated ion pairs in nanotubes (Izgorodina et al, 2014;Luo et al, 2013), in supercritical water (Chialvo et al, 1995;Plugatyr et al, 2011), and hybrid excitations in solution (Nicholson and Quirke, 2003;Reznikov and Shaposhnik, 2005;Maiti and Rogers, 2011;Lui et al, 2011;Farnum et al, 2011;Kielpinski, 2013). In recent years, the improved methods of direct ion pair study have been used (Westerlund et al, 2011;Besser-Rogac et al, 2011;.…”

“…The CCE in water solution of soil, vadose and saturation zones provides understanding of biogeochemical element cycles, models of anthropogenic emission of greenhouse gases (Peng et al, 2014), and anthropogenic CO 2 sink to the ocean (Ishii et al, 2014).…”