Air-sea gas exchange in Antarctic waters

Abstract

Abstract:The flux of gases between the atmosphere and the oceans can be calculated from the product of the concentration difference across the sea surface and a kinetic term, often called a transfer velocity. The transfer velocity is frequently parameterized in terms of wind speed, although the actual exchange process is also affected by waves, bubbles, wind fetch, and less certainly by surfactants and chemical reactivity. There is currently an uncertainty of about a factor of two in using the wind speed parameterization. In view of the windiness of the Southern Ocean, transfer velocities will often be high, although there are few published in situ measurements of transfer rates made in the region. Data for gas concentration fields in the Southern Ocean are generally sparse compared to other better studied oceanic areas. In this paper we discuss what is known for the region for carbon dioxide, including the oceanic sink for man-made inputs to the atmosphere; dimethyl sulphide, where there appears to be a substantial source, which has the potential for a significant climatic effect due to the low particulate loading in the region; and organo-halogen and alkyl nitrate gases, where marine emissions may play an important role in controlling the oxidation capacity of the Antarctic atmosphere.

340 years of atmospheric circulation characteristics reconstructed from an eastern Antarctic Peninsula ice core

“…Important factors in justifying such a link are that the easterly trajectories originate further south than the westerlies and that the Weddell Sea generally has a more northerly sea ice extent than to the west of the AP. Therefore, the easterly trajectories are much less likely to have tracked over open sea water, which is one of the sources of nitrate in precipitation [ Liss et al , 2004]. The opposite is true for the westerlies and the link is compounded by the fact that the other major source of nitrate ‐ transported from the stratosphere via the polar vortex [ Legrand and Mayewski , 1997] ‐ will also deliver nitrate from the west.…”

Air‐sea exchange of carbon dioxide in the Southern Ocean and Antarctic marginal ice zone

“…Between 30°S and 50°S, high winds and cold, productive waters contribute to strong carbon uptake. Global ocean circulation models show that the uncertainty in the Southern Ocean carbon budget is larger than the rest of the world oceans combined, partially due to use of different parameterizations of the gas transfer velocity [Liss et al, 2004]. The net Southern Ocean carbon budget calculated from the Takahashi et al [2009] (hereinafter T09) ΔpCO 2 climatology suggests a flux of À0.8 PgC yr À1 (a sink), while inversion models infer fluxes of À0.6 to À1.3 PgC yr À1 [Gloor et al, 2003;Patra et al, 2005].…”

“…The net Southern Ocean carbon budget calculated from the Takahashi et al [2009] (hereinafter T09) ΔpCO 2 climatology suggests a flux of À0.8 PgC yr À1 (a sink), while inversion models infer fluxes of À0.6 to À1.3 PgC yr À1 [Gloor et al, 2003;Patra et al, 2005]. Global ocean circulation models show that the uncertainty in the Southern Ocean carbon budget is larger than the rest of the world oceans combined, partially due to use of different parameterizations of the gas transfer velocity [Liss et al, 2004]. Reducing uncertainty in the gas transfer velocity used in models requires field measurements in harsh Southern Ocean conditions.…”

Wave Attenuation and Gas Exchange Velocity in Marginal Sea Ice Zone

“…Constraining the magnitude of the gas exchange velocity (k) at the air-sea interface in the Marginal Ice Zone (MIZ) has implications on estimating the fluxes of biogenic and anthropogenic gases such as carbon dioxide (Bates, 2006;Evans et al, 2015;Liss et al, 2004;Smedsrud et al, 2013;Takahashi et al, 2009) and methane (Elliott et al, 2011;Uhlig & Loose, 2017;Wåhlstr€ om & Meier, 2014). Gas exchange in the MIZ is complex and the relationship between sea ice concentration and carbon sink is poorly understood (Parmentier et al, 2013).…”