海气CO_2通量与涡动相关法应用研究进展

Advances in Air-Sea CO_2 Flux Study and the Application of Eddy Covariance Technique

海气CO2交换速率及通量的测定、估算是碳循环研究的重要内容。测定、估算海气CO2交换速率及通量有多种方法,但都有其局限性,准确定量海气碳通量的大小仍是碳循环研究的热点问题。当前应用最广泛的海气界面分压差法需要通过间接手段测定海气交换速率,交换速率和风速的关系基于经验公式,不确定性较大;而涡动相关法(eddy covariance/eddy correlation)是一种直接测量方法,理论上不需要任何经验参数,在近年来取得较大进展。综述了近年来国内外CO2海气交换速率及通量的测定、估算方法的研究进展,并对各种方法的原理、应用、优缺点进行了分析,着重介绍了涡动相关法测量CO2通量的原理、国内外研究现状、相对传统方法的优缺点以及发展前景等,对未来海气CO2交换速率及通量研究发展趋势和研究方法作了展望。

Determination of air-sea CO2 transfer velocity and flux is a key to constrain the global carbon fluxes. A widely used method to estimate air-sea CO2 flux has been based on so-called ＂ bulk＂ CO2 method. This method requires the determination of the difference between air and sea surface CO2 partial pressure and the gas transfer velocity. The latter is typically obtained through the empirical relationship between transfer velocity and wind speed. Such a simplification would potentially induce uncertainties in the flux estimation due to for instance, the lack of on site gas transfer velocity data. Eddy covariance method is a direct measurement method, which in theory does not require any empirical parameters. During the past decade, significant progress has been achieved in the application of eddy covariance method in measuring air-sea CO2 fluxes. This paper is attempting to provide an overview and a comparison between various techniques available for the measurement of air-sea CO2 transfer velocity and for the estimates of fluxes. Principle, merit and demerit of each method will be briefly introduced. Our special attention is given to the eddy covariance technique, one of the potentially promising micrometeorological method.