摘要
１９９８年淮河流域能量和水循环试验（ＨＵＢＥＸ）期间曾进行了１个月的近地面层湍流观测。分析不稳定条件下湍流的统计特性和谱特征，并与Ｍｏｎｉｎ－Ｏｂｕｋｈｏｖ相似理论进行了比较。结果表明，不稳定的时候各湍流量的统计特征与相似理论的预期相符。虽然不稳定条件下温度和湿度涨落的相关系数很高，谱的式样也相近．但湿度谱的峰值频率高于温度谱。协谱曲线的形状显示感热通量的谱峰较宽，表现出ｗ和Ｔ在较宽范围的强相关性，而水汽通量谱在高频段下降很快，说明水汽的输送更多地出现在低频部分。从谱相关系数可见，在近中性的时候，各尺度湍流涡的热量输送效率普遍较低，随着不稳定性增强而显著提高。分析还发现，不论不稳定性的程度如何，小尺度湍流的水汽输送效率都较低。水汽通量谱的相关系数随稳定度的变化不如热通量的谱相关系数大，表明近中性时除小尺度湍流外其他湍流涡的水汽输送效率高于热量输送。
Turbulent data for wind, temperature and humidity were collected in surface layer over paddy field during HUBEX 1998 field campaign. The turbulent statistics and the spectral characteristics under unstable conditions are presented in this paper and compared with Monin-Obukhov similarity (MOS) theory. The results show that normalized standard deviations and correlation coefficients for the turbulent fluctuations are in good agreement with the predictions of the MOS. The dimensionless frequency at spectral Peak of water vapor is higher than that for temperature at the same stability range. However, the spectral curves are similar and the correlation coefficient between T' and q' is large. The cospectrum of heat flux exhibits a flatter peak than the humidity flux. The analyses of the spectral correlation coefficients have found that the heat transfer efficiency for all turbulence components is relative low in near neutral conditions and dramatically increases in stronger unstable conditions. Quick drop of the spectral correlation coefficients for humidity flux at high frequency side shows the low transfer efficiency in the small scale turbulence. The dependency of the spectral correlation coefficients on the stability is somewhat weaker than the heat flux. It concludes that low frequency eddies are more efficient in water vapor transfer than in heat transfer under near neutral conditions.
出处
《气候与环境研究》
CSCD
2001年第2期221-227,共7页
Climatic and Environmental Research
基金
国家自然科学基金资助项目49675253和49794030
中国科学院大气物理研究所大气边界层物理与大气化学国家重点实验室(
