Surface ocean p CO₂ seasonality and sea-air CO₂ flux estimates for the North American east coast

Abstract

[1] Underway and in situ observations of surface ocean pCO 2 , combined with satellite data, were used to develop pCO 2 regional algorithms to analyze the seasonal and interannual variability of surface ocean pCO 2 and sea-air CO 2 flux for five physically and biologically distinct regions of the eastern North American continental shelf: the South Atlantic Bight (SAB), the Mid-Atlantic Bight (MAB), the Gulf of Maine (GoM), Nantucket Shoals and Georges Bank (NSþGB), and the Scotian Shelf (SS). Temperature and dissolved inorganic carbon variability are the most influential factors driving the seasonality of pCO 2 . Estimates of the sea-air CO 2 flux were derived from the available pCO 2 data, as well as from the pCO 2 reconstructed by the algorithm. Two different gas exchange parameterizations were used. The SS, GBþNS, MAB, and SAB regions are net sinks of atmospheric CO 2 while the GoM is a weak source. The estimates vary depending on the use of surface ocean pCO 2 from the data or algorithm, as well as with the use of the two different gas exchange parameterizations. Most of the regional estimates are in general agreement with previous studies when the range of uncertainty and interannual variability are taken into account. According to the algorithm, the average annual uptake of atmospheric CO 2 by eastern North American continental shelf waters is found to be between À3.4 and À5.4 Tg C yr À1 (areal average of À0.7 to À1.0 mol CO 2 m À2 yr À1 ) over the period

Air-sea CO<sub>2</sub> fluxes and the controls on ocean surface <i>p</i>CO<sub>2</sub> seasonal variability in the coastal and open-ocean southwestern Atlantic Ocean: a modeling study

“…This signal is dampened by DIC s , but also by ALK s in the case of the South Brazilian Shelf (SBS). This pattern of seasonal variation of the parameters on continental shelves agrees with the results from Signorini et al (2013) and Turi et al (2014), although with different absolute values. The pattern of diminishing variability towards subtropical continental shelves is also shown by Signorini et al (2013).…”

“…This pattern of opposing contributions of T and DIC was also found along the North American east coast by Signorini et al (2013), who attributed winter mixing and the springsummer biological drawdown as the processes responsible for pCO 2 and DIC variability. In the offshore subtropical region (ST) the pCO 2 anomalies have higher amplitudes than in the adjacent continental shelf (SEBS), and are driven mainly by temperature, with the other variables having minor contributions (Fig.…”

“…In order to assess the impact of different parameters on pCO 2 variability, we decompose pCO 2 with respect to T , S, DIC and ALK, following the approach of Lovenduski et al (2007); Doney et al (2009);Turi et al (2014) and Signorini et al (2013),…”

“…Blue represents a sink of atmospheric CO 2 and red a source. of observations, and PB is the bias normalized by the observations (Dabrowski et al, 2014;Stow et al, 2009). Basically if ME > 0.5, CF < 1 and PB < 20, this indicates that the model is "good/reasonable" when comparing to observations.…”

Hurricane Arthur and its effect on the short-term variability of pCO&lt;sub&gt;2&lt;/sub&gt; on the Scotian Shelf, NW Atlantic

“…The Scotian Shelf is a coastal ocean and these complex, multifactorial interactions result in challenges in determining the processes that control the high degree of variability reported in this region (Shadwick et al, 2010, Signorini et al, 2013, Shadwick and Thomas, 2014.…”