论文标题
近地表海洋动能从漂流者观测和全球高分辨率模型的频率依赖性
Frequency dependence of near-surface oceanic kinetic energy from drifter observations and global high-resolution models
论文作者
论文摘要
近地表海洋动能(KE)的地理变异性,频率含量和垂直结构对于空气相互作用,海洋生态系统,操作海洋学,污染物跟踪以及解释远程感知的速度测量很重要。在这里,与来自未经停滞和droged表面脱落器的KE相比,在海面(0 m)和15 m处的高分辨率全球模拟(Hycom和Massachusetts通用循环模型; MITGCM)的KE分别是在海面(0 m)和15 m处的KE。计算出低频($ <$ 0.5 cpd),近惯性,昼夜和半统一频段的全球地图和区域平均值。两种模型均表现出相对于漂流者值低的低频赤道KE。 Hycom近惯性KE高于MITGCM,并且更接近漂流者值,这可能是由于更频繁地更新的大气强迫。 HYCOM半抑制KE低于MITGCM,并且更接近漂流者值,这可能是由于包含参数化的地形内波力阻力。昼夜带中并发的潮汐谐波分析表明,大部分昼夜流是非潮汐的。我们计算了一个简单的近表面垂直结构的代理,在模型输出中,0 m ke与0 m ke加15 m ke的比例,以及未折叠的ke do droged ke plus droged ke在漂流者观测中。在大多数纬度和频带上,模型比率跟踪了误差线内的漂移比率。该比率的值表明除半任频带以外的所有频段中都有明显的垂直结构。在昼夜和低频带中,比率的纬度依赖性最大。
The geographical variability, frequency content, and vertical structure of near-surface oceanic kinetic energy (KE) are important for air-sea interaction, marine ecosystems, operational oceanography, pollutant tracking, and interpreting remotely sensed velocity measurements. Here, KE in high-resolution global simulations (HYbrid Coordinate Ocean Model; HYCOM, and Massachusetts Institute of Technology general circulation model; MITgcm), at the sea surface (0 m) and 15 m, are respectively compared with KE from undrogued and drogued surface drifters. Global maps and zonal averages are computed for low-frequency ($<$ 0.5 cpd), near-inertial, diurnal, and semi-diurnal bands. Both models exhibit low-frequency equatorial KE that is low relative to drifter values. HYCOM near-inertial KE is higher than in MITgcm, and closer to drifter values, probably due to more frequently updated atmospheric forcing. HYCOM semi-diurnal KE is lower than in MITgcm, and closer to drifter values, likely due to inclusion of a parameterized topographic internal wave drag. A concurrent tidal harmonic analysis in the diurnal band demonstrates that much of the diurnal flow is non-tidal. We compute a simple proxy of near-surface vertical structure, the ratio of 0 m KE to 0 m KE plus 15 m KE in model outputs, and undrogued KE to undrogued KE plus drogued KE in drifter observations. Over most latitudes and frequency bands, model ratios track the drifter ratios to within error bars. Values of this ratio demonstrate significant vertical structure in all frequency bands except the semidiurnal band. Latitudinal dependence in the ratio is greatest in diurnal and low-frequency bands.