Air‐sea gas transfer: Its dependence on wind stress, small‐scale roughness, and surface films
Air‐sea gas transfer: Its dependence on wind stress, small‐scale roughness, and surface films
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气海气体传递：其对风应力、小尺度粗糙度和表面薄膜的依赖性
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
B. Jähne
中科院分区：
文献类型：
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作者：
N. Frew;E. J. Bock;U. Schimpf;T. Hara;H. Haussecker;J. Edson;W. McGillis;R. Nelson;S. P. McKenna;B. M. Uz;B. Jähne
[1]研究了在低到中等风速（<10 m s-1）下风应力、小尺度波浪和表面膜对海-气气体交换的影响。1997年7月，在新英格兰科德角以南的沿海和近海沃茨进行了风应力、传热速度、表面波斜率和表面膜富集的同时观测，作为NSF-CoOP沿海海气化学通量研究的一部分。气体传输速度已外推水热传递速度来自红外图像和直接协方差和散装热通量估计。气体传输速度被发现遵循二次关系与风速，占75%-77%的方差，但高估了传输速度的存在下的表面膜。由摩擦速度代表的风应力的依赖性也是非线性的，反映了波场依赖的限制运输制度之间的过渡。相比之下，在40-800 rad m−1的波数范围内计算的均方斜率的依赖性被发现是线性的，并且与以前的实验室风浪研究结果一致。在表面膜的存在下，小尺度波的斜率谱和气体传输速度被衰减。大规模梯度的生物生产力和溶解有机物的观测表明，坡度和传输速度的减少更明显地与表面膜富集比与散装有机物浓度。均方斜率参数化解释了观测到的数据方差的1089 -95%，并且不会过度预测存在薄膜的传输速度。虽然气体传递速度与风速或均方斜率之间的特定关系随着用于将传热速度换算成气体传递速度的施密特数指数的选择而略微变化，但传热或气体传递速度与均方斜率的相关性始终优于与风速的相关性。
[1] The influence of wind stress, small-scale waves, and surface films on air-sea gas exchange at low to moderate wind speeds (<10 m s−1) is examined. Coincident observations of wind stress, heat transfer velocity, surface wave slope, and surface film enrichments were made in coastal and offshore waters south of Cape Cod, New England, in July 1997 as part of the NSF-CoOP Coastal Air-Sea Chemical Fluxes study. Gas transfer velocities have been extrapolated from aqueous heat transfer velocities derived from infrared imagery and direct covariance and bulk heat flux estimates. Gas transfer velocity is found to follow a quadratic relationship with wind speed, which accounts for ∼75–77% of the variance but which overpredicts transfer velocity in the presence of surface films. The dependence on wind stress as represented by the friction velocity is also nonlinear, reflecting a wave field-dependent transition between limiting transport regimes. In contrast, the dependence on mean square slope computed for the wave number range of 40–800 rad m−1 is found to be linear and in agreement with results from previous laboratory wind wave studies. The slope spectrum of the small-scale waves and the gas transfer velocity are attenuated in the presence of surface films. Observations over large-scale gradients of biological productivity and dissolved organic matter show that the reduction in slope and transfer velocity are more clearly correlated with surface film enrichments than with bulk organic matter concentrations. The mean square slope parameterization explains ∼89–95% of the observed variance in the data and does not overpredict transfer velocities where films are present. While the specific relationships between gas transfer velocity and wind speed or mean square slope vary slightly with the choice of Schmidt number exponent used to scale the heat transfer velocities to gas transfer velocities, the correlation of heat or gas transfer velocity with mean square slope is consistently better than with wind speed.