| 摘要: |
| 基于黄海上连续14 d 的浮标观测资料, 采用多尺度分解法确定了海气通量涡相关法计算中的截断时间尺度, 并分析了该截断时间尺度的特征及其对感热通量计算的影响。研究结果是: 由多尺度分解法获得的湍通量截断时间尺度可将总通量中湍通量和中尺度通量分离开来, 截断时间尺度随着湍流强度或水平风速的增加而增加, 且感热通量的截断时间尺度大于动量通量的截断时间尺度; 在弱湍流状态下(σw<0.3 m/s), 动量通量和感热通量的截断时间尺度主要分布在100 s 左右, 湍通量和总通量之间差别较大; 在湍流较强时(σw>0.3 m/s), 动量通量和感热通量的截断时间尺度主要分布在800 s 左右,湍通量和总通量之间差别较小; 通过计算和分析不同截断时间尺度下感热通量的平均值和不确定性,可以看出截断时间尺度对感热通量的平均值的影响较小, 但对感热通量的不确定性有很大的影响, 这两种影响之间的差别会随着湍流强度的增加而减小。海气通量涡相关法计算中, 正确的截断时间尺度的选取可以获得真实可靠的海气通量数据, 也为进一步认识和了解上层海洋与大气之间的相互作用提供重要的科学依据。 |
| 关键词: 平均时间尺度 海气通量 谱隙 多尺度分解法 截断时间尺度 |
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| 基金项目:国家重点基础研究发展计划(2011CB403501); 国家自然科学基金(40876012); 国家基金委创新群体项目(40821004) |
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| On the average time scale used in the calculations of the air-sea fluxes by eddy covariance method |
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| Abstract: |
| Based on data collected at a moored buoy located in the Yellow Sea for a period of 14 days, the cutoff time scale (CTS), a parameter in the calculations of the air-sea fluxes by the eddy covariance method was determined by the multiresolution decomposition method, and could be used in separating turbulent fluxes and mesoscale fluxes from the total air-sea fluxes. The CTS increased with the crease of turbulence intensity or wind velocity.The CTS of the sensible heat flux was always longer than that of the momentum flux. When the turbulence intensity was less than 0.3 m/s, most of CTS of the momentum and sensible heat fluxes were around 100 s and the difference between the turbulent and total fluxes was large; when the turbulence intensity is larger than 0.3 m/s, most of CTSs were around 800 s and the turbulent fluxwas similar to that of total fluxes. The calculation and analysis of the average and uncertainty of sensible heat flux indicated the CTS has more influence on the average value than on the uncertainty of the flux and such a difference became smaller as the turbulence intensity increases. The choice of CTS is important to get the air-sea fluxes, providing a scientific basis for further understanding the interaction between the ocean and atmosphere. |
| Key words: average time scale air-sea fluxes spectral gap multiresolution decomposition cutoff time scale |
