Turbulent Variance Characteristics of Temperature and Humidity over a Non-uniform Land Surface for an Agricultural Ecosystem in China

• Published in: Advances in atmospheric sciences Vol. 23; no. 3; pp. 365 - 374
• Main Author: 高志球 卞林根 谌志刚 Michael SPARROW 张佳华
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.05.2006; Chinese Academy of Meteorological Sciences, Beijing 100081; State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029%Chinese Academy of Meteorological Sciences,Beijing,100081%Guangzhou Central Meteorological Observatory,Guangzhou,510080%International CLIVAR Project Office, Southampton Oceanography Centre, Southampton, U.K
• Subjects: Agricultural ecosystems; Agriculture; Atmospheric sciences; Ecosystems; Fluctuations; Humidity; Latent heat; Sensible heat; Studies; Temperature; Water vapor; 农业生态系统; 协方差; 土地覆盖率; 通量方差; China, People's Rep; non-uniform land surface; flux variance; turbulent fluxes; eddy covariance
• ISSN: 0256-1530; 1861-9533
• DOI: 10.1007/s00376-006-0365-y

This paper describes the application of the variance method for flux estimation over a mixed agricultural region in China. Eddy covariance and flux variance measurements were conducted in a near-surface layer over a non-uniform land surface in the central plain of China from 7 June to 20 July 2002. During this period, the mean canopy height was about 0.50 m. The study site consisted of grass （10% of area）, beans （15%）, corn （15%） and rice （60%）. Under unstable conditions, the standard deviations of temperature and water vapor density （normalized by appropriate scaling parameters）, observed by a single instrument, followed the Monin-Obukhov similarity theory. The similarity constants for heat （CT） and water vapor （Cq） were 1.09 and 1.49, respectively. In comparison with direct measurements using eddy covariance techniques, the flux variance method, on average, underestimated sensible heat flux by 21% and latent heat flux by 24%, which may be attributed to the fact that the observed slight deviations （20% or 30% at most） of the similarity ＂constants＂ may be within the expected range of variation of a single instrument from the generally-valid relations.