海-气界面气体交换速率和全球海洋CO_2通量的初步研究

A Preliminary Study on Sea-Air Gas Transfer Velocity and Global Ocean CO_2 Flux

在全球气候变暖的背景下,准确估计海-气界面CO_2通量显得非常重要。海-气界面CO_2通量通常利用块体公式,由气体交换速率与大气和海洋的CO_2分压差(ΔpCO_2)的乘积来计算。影响气体交换速率的因素很多,但一般经验性地与风速相联系,其测量方法通常有物质平衡法和涡相关法,后者给出的结果比前者大。基于前人的两类观测数据,提出了一个以风速为函数的气体交换速率新方案。在此基础上,基于最新的SOCATv2(Surface Ocean CO_2Atlas version 2)的ΔpCO_2数据集,计算了1982—2011年海洋对CO_2的净吸收量及其年变化,发现2001年海洋净吸收量存在一个最小值,2001年之后,海洋净吸收量迅速增加,而这一年变化特征主要由ΔpCO_2的年变化特征所决定,风速的影响可以忽略。

The accurate estimate of the sea-air CO_2 fluxes becomes more important on the context of global warming.It is usually adopted the bulk formula in which the gas transfer velocity and CO_2 partial pressure difference between sea and air（ΔpCO_2）are needed.Although many factors influence on gas transfer velocity,it is traditionally related to wind speed only with empirical formula.Gas transfer velocity is usually determined by the substance equilibrium and eddy correlation methods.Based on the previous studies,it is found that gas transfer velocities by the former method are smaller than those by the latter method,and a new parameterization of gas transfer velocity as a function of wind speed is proposed.Applied the latest dada set ofΔpCO_2 called SOCAT v2（Surface Ocean CO_2 Atlas version 2）,the sea-air CO_2 fluxesand net uptakes by ocean from 1982 to 2011 are calculated.It is found that the net uptake by ocean has a minimum value in 2001,and increases quickly from 2001.Furthermore,this annual variability is mainly dominated by the feature ofΔpCO_2,and the effect of wind speed can be ignored.