https://scholars.lib.ntu.edu.tw/handle/123456789/372900
標題: | Evaluation of the relaxed eddy accumulation coefficient at various wetland ecosystems | 作者: | Tsai, J.-L. Tsuang, B.-J. Kuo, P.-H. Tu, C.-Y. Chen, C.-L. Hsueh, M.-T. CHENG-SHANG LEE Yao, M.-H. Hsueh, M.-L. |
關鍵字: | Relaxed eddy accumulation method; Scalar similarity; Trace gas flux; Wetlands; Wind deadband | 公開日期: | 2012 | 卷: | 60 | 起(迄)頁: | 336-347 | 來源出版物: | Atmospheric Environment | 摘要: | Field measurements at various wetland ecosystems were conducted to investigate the coefficients b for different scalars in the relaxed eddy accumulation method. These measurements were performed at paddy, marsh and lagoon fields using the eddy covariance system to collect data with a sampling rate of 10 Hz. Without the application of a wind deadband, the mean median values of b were found to be 0.55 for paddy, 0.57 for marsh and 0.56 for lagoon for all scalar quantities under unstable and near-neutral conditions. However, the median values of b under stable conditions steadily increase with stability. The results of estimated b were well described by proposed relationships as a function of the dimensionless stability parameter z/L. Scalar similarity between carbon dioxide, temperature and water vapor showed a distinct diurnal pattern and change within the day where good scalar correlations were observed at paddy and marsh during daytime, but poor scalar correlations were observed at lagoon. With the application of wind deadband, the reductions of the normalized b factors, b REA, related to the increase of deadband values were evaluated and the results were compared with the reported relationships in the literature. The relative minimal variability of the normalized b REA was found when the wind deadband was equal to 0.8. From the diurnal variation of b REA, the relative maximum values of b REA factors occurred around noon, and lower values were observed in the early morning and late afternoon. Daily median b 0 values for various scalars under unstable and neutral conditions over paddy from the beginning to the end of the study period were used to verify the independence of the variations in surface roughness. © 2012 Elsevier Ltd. |
URI: | http://www.scopus.com/inward/record.url?eid=2-s2.0-84864151656&partnerID=MN8TOARS http://scholars.lib.ntu.edu.tw/handle/123456789/372900 |
DOI: | 10.1016/j.atmosenv.2012.06.081 | SDG/關鍵字: | Deadbands; Diurnal pattern; Diurnal variation; Eddy covariance systems; Field measurement; Maximum values; Median value; Near-neutral conditions; Neutral conditions; Relaxed Eddy accumulation; Sampling rates; Scalar quantities; Scalar similarity; Stability parameters; Trace gas; Wetland ecosystem; Carbon dioxide; Ecosystems; Lakes; Surface roughness; Wetlands; carbon dioxide; carbon dioxide; data acquisition; dimensionless number; diurnal variation; eddy covariance; gas exchange; lagoon; marsh; paddy field; parameterization; sampling; surface roughness; temperature profile; trace gas; water vapor; wetland; wind profile; wind velocity; article; circadian rhythm; ecosystem; lagoon; land use; marsh; priority journal; surface property; temperature; water vapor; wetland; wetland ecosystem; wind |
顯示於: | 大氣科學系 |
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