Air–sea gas fluxes are commonly estimated using wind-based parametrizations of the gas transfer velocity. However, neglecting gas exchange forcing mechanisms – other than wind speed – may lead to large uncertainties in the flux estimates and the carbon budgets, in particular, in heterogeneous environments such as marginal seas and coastal areas. In this study we investigated the impact of including relevant processes to the air–sea CO${}_2$ flux parametrization for the Baltic Sea. We used six parametrizations of the gas transfer velocity to evaluate the effect of precipitation, water-side convection, and surfactants on the net CO${}_2$ flux at regional and sub-regional scale. The differences both in the mean CO${}_2$ fluxes and the integrated net fluxes were small between the different cases. However, the implications on the seasonal variability were shown to be significant. The inter-annual and spatial variability were also found to be associated with the forcing mechanisms evaluated in the study. In addition to wind, water-side convection was the most relevant parameter controlling the air–sea gas exchange at seasonal and inter-annual scales. The effect of precipitation and surfactants seemed negligible in terms of the inter-annual variability. The effect of water-side convection and surfactants resulted in a reduction of the downward fluxes, while precipitation was the only parameter that resulted in an enhancement of the net uptake in the Baltic Sea.

通常使用基于风的气体传输速度参数化来估计海气通量。然而，忽略风速以外的气体交换强迫机制可能会导致通量估计和碳预算的巨大不确定性，特别是在边缘海和沿海地区等异质环境中。在这项研究中，我们调查了包括相关过程对海气 CO2 的影响${}_2$波罗的海的通量参数化。我们使用了气体传输速度的六个参数来评估沉淀、水侧对流和表面活性剂对净 CO2 的影响${}_2$区域和次区域尺度的通量。平均 CO 的差异${}_2$不同情况下的通量和积分净通量较小。然而，对季节性变化的影响被证明是显着的。还发现年际和空间变化与研究中评估的强迫机制有关。除风外，水侧对流是控制季节和年际尺度海气交换的最相关参数。就年际变化而言，降水和表面活性剂的影响似乎可以忽略不计。水侧对流和表面活性剂的影响导致向下通量的减少，而降水是导致波罗的海净吸收增加的唯一参数。