Wave Attenuation and Gas Exchange Velocity in Marginal Sea Ice Zone

Abstract

The gas transfer velocity in marginal sea ice zones exerts a strong control on the input of anthropogenic gases into the ocean interior. In this study, a sea state‐dependent gas exchange parametric model is developed based on the turbulent kinetic energy dissipation rate. The model is tuned to match the conventional gas exchange parametrization in fetch‐unlimited, fully developed seas. Next, fetch limitation is introduced in the model and results are compared to fetch limited experiments in lakes, showing that the model captures the effects of finite fetch on gas exchange with good fidelity. Having validated the results in fetch limited waters such as lakes, the model is next applied in sea ice zones using an empirical relation between the sea ice cover and the effective fetch, while accounting for the sea ice motion effect that is unique to sea ice zones. The model results compare favorably with the available field measurements. Applying this parametric model to a regional Arctic numerical model, it is shown that, under the present conditions, gas flux into the Arctic Ocean may be overestimated by 10% if a conventional parameterization is used.

The FuGas 2.3 Framework for Atmosphere–Ocean Coupling: Comparing Algorithms for the Estimation of Solubilities and Gas Fluxes

“…Our findings corroborate recent conclusions that the wave state is fundamental for accurate estimates of gas transfer velocities at the fetch-limited coastal ocean [50,57]. Furthermore, our conclusions also agree with Jackson et al [88] and Shuiqing and Dongliang [49] when inferring about the open ocean.…”

“…With the optional coupling of the sea state and wind velocity forcings (through the iWLP joint estimate of z 0 and u * ), the FuGas enables an enhanced representation of local conditions that was demonstrated to be fundamental for the estimation of transfer velocities in fetch-limited situations [50,55,57]. This coupling agrees with observations that k w scales with the turbulent kinetic energy dissipation at the sea surface (ε), and that ε is better reflected by the sea state [54,56].…”

“…Also, we coupled the Weather Research and Forecasting (WRF) atmospheric model to the WaveWatch III (WW3)-NEMO oceanographic model using simulated data from the European coastal ocean. These new tests are particularly relevant given recent findings that the sea state in fetch-limited locations (as is the coastal ocean) has an influence on the transfer velocity, by contrast with that from the fetch-unlimited open ocean [50,55,57].…”

“…Such are the formulations proposed by Carini et al [30] or Raymond and Cole [31], accounting only for u 10 , or by Borges et al [32], adding current drag with the bottom. Meanwhile, new evidence emerged for the effects of the sea surface cool-skin and warm-layer [33][34][35][36][37][38], atmospheric stability [39,40], wave-breaking [41][42][43][44][45][46][47][48][49][50], water surface renewal [28,[51][52][53][54][55][56][57], surfactants [28,[58][59][60] and rain [61][62][63][64], just to mention a few examples from an extensive list of published works. In addition to their single influence, these factors also interact.…”

A Structure Function Model Recovers the Many Formulations for Air‐Water Gas Transfer Velocity

“…DMS is not impacted by bubble‐mediated transfer and is thus an ideal tracer for exploring k L in the absence of bubbles at high U 10 . Few experiments support the decline of k L for DMS with increasing U 10 (Bell et al, , ; Huebert et al, ), while others do not offer such strong evidence (Bigdeli et al, ). Some laboratory studies suggest a saturation behavior of k L with u ∗ at very high u ∗ (Komori et al, ; Vlahos & Monahan, ).…”