One-dimensional modelling of convective CO2 exchange in the Tropical Atlantic

Jeffery, C. D.; Woolf, David; Robinson, I. S.; Donlon, Craig

doi:10.1016/j.ocemod.2007.07.003

Cited by 48 publications

(53 citation statements)

References 53 publications

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“…The fluxes are estimated using the satellite sea-surface temperature (SST) and the SSTÁpCO 2w relation in Table 1, magnitude indicated by the colour bar. algorithm (Fairall et al, 2000;Jeffery et al, 2007). However, a more accurate description of the behaviour of k during upwelling is needed to implement the effects into the algorithm.…”

Section: Discussionmentioning

confidence: 99%

Influence of coastal upwelling on the air–sea gas exchange of CO2 in a Baltic Sea Basin

Norman

Parampil

Rutgersson

2013

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T During coastal upwelling cold water from the ocean interior with high CO 2 concentration is brought up to the surface, allowing this water to interact with the atmosphere. This sets the stage for events with potentially altered seaÁair CO 2 fluxes. Four upwelling events off the east coast of Gotland in the Baltic Sea were analyzed to assess the impact of upwelling on the airÁsea exchange of CO 2 . For each event, the observed pCO 2 were found to be a function of sea-surface temperature (SST) in the upwelling area, which allowed satellite observations of SST to form a proxy for surface water pCO 2 . A bulk formula was then used to estimate the airÁsea CO 2 flux during the upwelling events. The results show that the CO 2 fluxes in the study area are highly influenced by the upwelling. Comparing with idealized cases without upwelling yields relatively large differences, ranging between 19 and 250% in reduced uptake/increased emission of CO 2 . Upwelling may also influence the CO 2 fluxes on larger scales. A rough estimate indicates that it may also be of significant importance for the average annual CO 2 flux from the Baltic Sea. Including upwelling possibly decreases the Baltic Sea annual average uptake by up to 25%.

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Section: Discussionmentioning

confidence: 99%

Influence of coastal upwelling on the air–sea gas exchange of CO2 in a Baltic Sea Basin

Norman

Parampil

Rutgersson

2013

Tellus B: Chemical and Physical Meteorology

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“…The wind-induced water friction velocity and heatinduced water convective velocity were coupled as total water velocity by Jeffery et al (2007):…”

Section: The Model Derived In This Studymentioning

confidence: 99%

Effects of cooling and internal wave motions on gas transfer coefficients in a boreal lake

Heiskanen¹,

Mammarella²,

Haapanala³

et al. 2014

Tellus B: Chemical and Physical Meteorology

158

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A B S T R A C TLakes and other inland waters contribute significantly to regional and global carbon budgets. Emissions from lakes are often computed as the product of a gas transfer coefficient, k 600 , and the difference in concentration across the diffusive boundary layer at the airÁwater interface. Eddy covariance (EC) techniques are increasingly being used in lacustrine gas flux studies and tend to report higher values for derived k 600 than other approaches. Using results from an EC study of a small, boreal lake, we modelled k 600 using a boundarylayer approach that included wind shear and cooling. During stratification, fluxes estimated by EC occasionally were higher than those obtained by our models. The high fluxes co-occurred with winds strong enough to induce deflections of the thermocline. We attribute the higher measured fluxes to upwelling-induced spatial variability in surface concentrations of CO 2 within the EC footprint. We modelled the increased gas concentrations due to the upwelling and corrected our k 600 values using these higher CO 2 concentrations. This approach led to greater congruence between measured and modelled k values during the stratified period. k 600 has a well-resolved and Âcubic relationship with wind speed when the water column is unstratified and the dissolved gases well mixed. During stratification and using the corrected k 600 , the same pattern is evident at higher winds, but k 600 has a median value of Â7 cm h(1 when winds are less than 6 m s (1 , similar to observations in recent oceanographic studies. Our models for k 600 provide estimates of gas evasion at least 200% higher than earlier wind-based models. Our improved k 600 estimates emphasize the need for integrating within lake physics into models of greenhouse gas evasion.

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“…To overcome this limitation we use the NOAA Coupled Ocean Atmosphere Response Experiment (COARE) gas transfer parameterisation (Fairall et al, 2000) which is physically (rather than empirically) based. We also include a modification to this parameterisation by Jeffery et al (2007) to include the effects of nighttime convective overturn of the water column. A brief description of this method is given below and the variations in k due to wind and tepmerature are shown in Fig.…”

Section: Gas Transfer Velocity Kmentioning

confidence: 99%

“…However, in order to include the increased gas transfer caused by convective overturn, Jeffery et al (2007) modified the expression for u * w to include waterside "gustiness". Thus u * w is newly defined as…”

Section: Gas Transfer Velocity Kmentioning

confidence: 99%

“…Moreover, a field experiment has shown that it is possible for CO 2 fluxes to have only a weak dependence on wind speed but a strong dependence on the diurnal heating cycle (e.g., GasEx-2001 in the Equatorial Pacific; McGillis et al, 2004). Therefore, in this study we use a more complex physically-based parameterisation that includes buoyancy driven, as well as wind driven, gas transfer, by Fairall et al (2000) with modifications by Jeffery et al (2007); along with a slightly different formulation for the flux (Eq. 4).…”

Section: Introductionmentioning

confidence: 99%

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The impact of diurnal variability in sea surface temperature on the central Atlantic air-sea CO2 flux

et al. 2009

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Abstract. The effect of diurnal variations in sea surface temperature (SST) on the air-sea flux of CO 2 over the central is evaluated for [2005][2006]. We use high spatial resolution hourly satellite ocean skin temperature data to determine the diurnal warming ( SST). The CO 2 flux is then computed using three different temperature fields -a foundation temperature (T f , measured at a depth where there is no diurnal variation), T f plus the hourly SST and T f plus the monthly average of the SSTs. This is done in conjunction with a physically-based parameterisation for the gas transfer velocity (NOAA-COARE). The differences between the fluxes evaluated for these three different temperature fields quantify the effects of both diurnal warming and diurnal covariations. We find that including diurnal warming increases the CO 2 flux out of this region of the Atlantic for 2005-2006 from 9.6 Tg C a −1 to 30.4 Tg C a −1 (hourly SST) and 31.2 Tg C a −1 (monthly average of SST measurements). Diurnal warming in this region, therefore, has a large impact on the annual net CO 2 flux but diurnal covariations are negligible. However, in this region of the Atlantic the uptake and outgassing of CO 2 is approximately balanced over the annual cycle, so although we find diurnal warming has a very large effect here, the Atlantic as a whole is a very strong carbon sink (e.g. −920 Tg C a −1 Takahashi et al., 2002) making this is a small contribution to the Atlantic carbon budget.

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One-dimensional modelling of convective CO2 exchange in the Tropical Atlantic

Cited by 48 publications

References 53 publications

Influence of coastal upwelling on the air–sea gas exchange of CO<sub>2</sub> in a Baltic Sea Basin

Influence of coastal upwelling on the air–sea gas exchange of CO<sub>2</sub> in a Baltic Sea Basin

Effects of cooling and internal wave motions on gas transfer coefficients in a boreal lake

The impact of diurnal variability in sea surface temperature on the central Atlantic air-sea CO<sub>2</sub> flux

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One-dimensional modelling of convective CO2 exchange in the Tropical Atlantic

Cited by 48 publications

References 53 publications

Influence of coastal upwelling on the air–sea gas exchange of CO<sub>2</sub> in a Baltic Sea Basin

Influence of coastal upwelling on the air–sea gas exchange of CO<sub>2</sub> in a Baltic Sea Basin

Effects of cooling and internal wave motions on gas transfer coefficients in a boreal lake

The impact of diurnal variability in sea surface temperature on the central Atlantic air-sea CO&lt;sub&gt;2&lt;/sub&gt; flux

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The impact of diurnal variability in sea surface temperature on the central Atlantic air-sea CO<sub>2</sub> flux