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A compilation of surface water nutrient (phosphate, nitrate, and silicate) and partial pressure of CO2 (pCO2) observations from 1961 to 2016 reveals seasonal and interannual variability in the North Pacific. Nutrients and calculated dissolved inorganic carbon (DIC) reach maximum concentrations in March and minimum in August. Nutrient and DIC variability is in-phase (anti-phase) with changes in the mixed layer depth (sea surface temperature) north of 30 °N, and it is anti-phase (in-phase) with changes in Chl-a north of 40 °N (in 30 °N–40 °N). Seasonal drawdown of nutrients and DIC is larger toward the northwest and shows a local maximum in the boundary region between the subarctic and subtropics. Stoichiometric ratios of seasonal drawdown show that, compared to nitrate, silicate drawdown is large in the northwestern subarctic including the Bering and Okhotsk seas, and drawdown of carbon is larger toward the south. Net community production in mixed layer from March to July is estimated to be more than 6 gC/m2/mo in the boundary region between the subarctic and subtropics, the western subarctic, the Gulf of Alaska, and the Bering Sea. Nutrient and DIC concentrations vary with the Pacific Decadal Oscillation and the North Pacific Gyre Oscillation which cause changes in horizontal advection and vertical mixing. The DIC trend is positive in all analysis area and large in the western subtropics (> 1.0 μmol/l/yr). Averaged over the analysis area, it is increasing by 0.77 ± 0.03 μmol/l/yr (0.75 ± 0.02 μmol/kg/yr). [ABSTRACT FROM AUTHOR]

We used more than 25,000 nutrient samples to elucidate for the first time basin-scale distributions and seasonal changes of surface ammonium (NH ) and nitrite (NO ) concentrations in the Pacific Ocean. The highest NH , NO , and nitrate (NO ) concentrations were observed north of 40°N, in the coastal upwelling region off the coast of Mexico, and in the Tasman Sea. NH concentrations were elevated during May-October in the western subarctic North Pacific, May-December in the eastern subarctic North Pacific, and June-September in the subtropical South Pacific. NO concentrations were highest in winter in both hemispheres. The seasonal cycle of NH was synchronous with NO , NO , and satellite chlorophyll a concentrations in the western subtropical South Pacific, whereas it was synchronous with chlorophyll- a but out of phase with NO and NO in the subarctic regions. [ABSTRACT FROM AUTHOR]