Parameterizing bubble‐mediated air‐sea gas exchange and its effect on ocean ventilation

Liang, Jun‐Hong; Deutsch, Curtis; McWilliams, James C.; Baschek, Burkard; Sullivan, Peter P.; Chiba, David

doi:10.1002/gbc.20080

Cited by 122 publications

(227 citation statements)

References 69 publications

(148 reference statements)

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“…The TMM has been applied to a wide range of problems, including simulating anthropogenic carbon uptake and radiocarbon by the ocean (Graven et al, 2012), simulating noble gases to improve the parameterization of air-sea gas transfer (Nicholson et al, 2011;Liang et al, 2013) and investigate ocean ventilation (Nicholson et al, 2016), studying ocean proxy (Siberlin and Wunsch, 2011) and radiocarbon (Koeve et al, 2015) timescales, investigating the mechanisms controlling nutrient ratios (Weber and Deutsch, 2010), modeling the cycling of particle reactive geochemical tracers Siddall et al, 2008;Vance et al, 2017), estimating respiration in the ocean from oxygen utilization rates (Duteil et al, 2013;Koeve and Kähler, 2016), demonstrating the utility of atmospheric potential oxygen measurements to constrain ocean heat transport , modeling the ocean's CaCO 3 (Koeve et al, 2014) and nitrogen (Kriest and Oschlies, 2015) cycles; studying the impact of the Southern Ocean on global ocean oxygen (Keller et al, 2016), estimating the flux of organic matter (Wilson et al, 2015), and biogeochemical parameter sensitivity (Khatiwala, 2007;Kriest et al, 2010Kriest et al, , 2012 and optimization (Priess et al, 2013b, a;Kriest et al, 2017).…”

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confidence: 99%

Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers

et al. 2017

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Abstract. Conventional integration of Earth system and ocean models can accrue considerable computational expenses, particularly for marine biogeochemical applications. "Offline" numerical schemes in which only the biogeochemical tracers are time stepped and transported using a precomputed circulation field can substantially reduce the burden and are thus an attractive alternative. One such scheme is the "transport matrix method" (TMM), which represents tracer transport as a sequence of sparse matrix-vector products that can be performed efficiently on distributed-memory computers. While the TMM has been used for a variety of geochemical and biogeochemical studies, to date the resulting solutions have not been comprehensively assessed against their "online" counterparts. Here, we present a detailed comparison of the two. It is based on simulations of the state-of-the-art biogeochemical sub-model embedded within the widely used coarse-resolution University of Victoria Earth System Climate Model (UVic ESCM). The default, non-linear advection scheme was first replaced with a linear, third-order upwind-biased advection scheme to satisfy the linearity requirement of the TMM. Transport matrices were extracted from an equilibrium run of the physical model and subsequently used to integrate the biogeochemical model offline to equilibrium. The identical biogeochemical model was also run online. Our simulations show that offline integration introduces some bias to biogeochemical quantities through the omission of the polar filtering used in UVic ESCM and in the offline application of time-dependent forcing fields, with high latitudes showing the largest differences with respect to the online model. Differences in other regions and in the seasonality of nutrients and phytoplankton distributions are found to be relatively minor, giving confidence that the TMM is a reliable tool for offline integration of complex biogeochemical models. Moreover, while UVic ESCM is a serial code, the TMM can be run on a parallel machine with no change to the underlying biogeochemical code, thus providing orders of magnitude speed-up over the online model.

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confidence: 99%

Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers

et al. 2017

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“…For oxygen Woolf and Thorpe (1991) report this value to be 9 m s −1 . Liang et al (2013) argue that bubble supersaturation effects at a given temperature differ significantly among parametrisations, and their comparison between Stanley et al (2009), Woolf andThorpe (1991), and their own parametrisation demonstrates differences in the order of 50 % for argon. The Woolf and Thorpe (1991) parametrisation does not account for any temperature or solubility dependence and is derived from calculated bubbled fields; implementation is however straightforward and the large relative uncertainties in the bubble term will be accounted for in the sensitivity analysis outlined below.…”

Section: Model Implementationmentioning

confidence: 95%

“…The injection of bubbles into the mixed layer through wave action can supersaturate the surface waters even if net gas exchange is zero (Liang et al, 2013). Here we utilise a modern k w parametrisation with an explicit bubble equilibrium fractional supersaturation parametrisation B, which enables the influence of the two elements on the NCP estimate to be quantified independently.…”

Section: Model Implementationmentioning

confidence: 99%

“…Water bath calibrations have confirmed the SmartBuoy temperature sensors to be accurate to within ±0.1 • C. García and Gordon (1992) provide an uncertainty estimate for the measurement of their oxygen solubility parameterisation of 0.3 %. We have selected a 50 % uniform uncertainty distribution for B, the equilibrium bubble supersaturation term, based on the assessment of parametrisations by Liang et al (2013).…”

Section: Uncertainty Distributionsmentioning

confidence: 99%

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Uncertainty and sensitivity in optode-based shelf-sea net community production estimates

et al. 2016

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Abstract. Coastal seas represent one of the most valuable and vulnerable habitats on Earth. Understanding biological productivity in these dynamic regions is vital to understanding how they may influence and be affected by climate change. A key metric to this end is net community production (NCP), the net effect of autotrophy and heterotrophy; however accurate estimation of NCP has proved to be a difficult task. Presented here is a thorough exploration and sensitivity analysis of an oxygen mass-balance-based NCP estimation technique applied to the Warp Anchorage monitoring station, which is a permanently well-mixed shallow area within the River Thames plume. We have developed an opensource software package for calculating NCP estimates and air-sea gas flux. Our study site is identified as a region of net heterotrophy with strong seasonal variability. The annual cumulative net community oxygen production is calculated as (−5 ± 2.5) mol m −2 a −1 . Short-term daily variability in oxygen is demonstrated to make accurate individual daily estimates challenging. The effects of bubble-induced supersaturation is shown to have a large influence on cumulative annual estimates and is the source of much uncertainty.

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“…The observed SF 6 and CFC-12 supersaturations are consistent with injecting and completely dissolving a few cc's of modern air (SF 6 = 7.7 ppt and CFC-12 = 526 ppt) into each kilogram of nearsurface seawater. According to Liang et al (2013), it can be assumed that bubble effects lead to elevated surface tracer concentrations during heavy wind conditions. The degree of supersaturation depends on the gas solubility; i.e., less soluble gases are more affected than soluble ones.…”

Section: Saturation Effectsmentioning

confidence: 99%

Perspectives of transient tracer applications and limiting cases

2015

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Abstract. Currently available transient tracers have different application ranges that are defined by their temporal input (chronological transient tracers) or their decay rate (radioactive transient tracers). Transient tracers range from tracers for highly ventilated water masses such as sulfur hexafluoride (SF 6 ) through tritium ( 3 H) and chlorofluorocarbons (CFCs) up to tracers for less ventilated deep ocean basins such as argon-39 ( 39 Ar) and radiocarbon ( 14 C). In this context, highly ventilated water masses are defined as water masses that have been in contact with the atmosphere during the last decade. Transient tracers can be used to empirically constrain the transit time distribution (TTD), which can often be approximated with an inverse Gaussian (IG) distribution. The IG-TTD provides information about ventilation and the advective/diffusive characteristics of a water parcel.Here we provide an overview of commonly used transient tracer couples and the corresponding application range of the IG-TTD by using the new concept of validity areas. CFC-12, CFC-11 and SF 6 data from three different cruises in the South Atlantic Ocean and Southern Ocean as well as 39 Ar data from the 1980s and early 1990s in the eastern Atlantic Ocean and the Weddell Sea are used to demonstrate this method. We found that the IG-TTD can be constrained along the Greenwich Meridian south to 46 • S, which corresponds to the Subantarctic Front (SAF) denoting the application limit. The Antarctic Intermediate Water (AAIW) describes the limiting water layer in the vertical. Conspicuous high or lower ratios between the advective and diffusive components describe the transition between the validity area and the application limit of the IG-TTD model rather than describing the physical properties of the water parcel. The combination of 39 Ar and CFC data places constraints on the IG-TTD in the deep water north of the SAF, but not beyond this limit.

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Parameterizing bubble‐mediated air‐sea gas exchange and its effect on ocean ventilation

Cited by 122 publications

References 69 publications

Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers

Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers

Uncertainty and sensitivity in optode-based shelf-sea net community production estimates

Perspectives of transient tracer applications and limiting cases

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