北太平洋对人为二氧化碳吸收的数值模拟

Numerical simulations of uptake of anthropogenic CO_2 in the North Pacific

采用一个开边界海盆尺度环流模式研究人为CO2在北太平洋的吸收和分布,并与闭边界模式的模拟结果进行了比较.模拟结果表明,西北太平洋和赤道东太平洋是两个重要的人为CO2汇.使用较大的等密度面扩散系数使得西北太平洋人为CO2通量增大,而赤道海区通量减小(RUN2).与闭边界模式相比,开边界模式中该两个区域的人为CO2通量都增加了.1800~1997年间,北太平洋共吸收人为CO223.75GtC(1Gt=1×1015g,RUN1).副极地海区是人为CO2的一个重要输出区,能输出人为CO2吸收量的38%~54%,而20°N^30°N海区是人为CO2的一个重要贮存区,占整个北太平洋的24%.开边界对于10°N以南太平洋吸收和贮存人为CO2有很大影响.与基于观测资料的估计相比,虽然模式低估了西北太平洋的人为CO2的穿透,高估了东北太平洋的人为CO2的穿透,但总的说来,模式比较好地估计了人为CO2在北太平洋的贮存.

A basin-wide ocean general circulation model with the open southern boundary condition is employed to study the uptake and distribution of anthropogenic CO2 in the North Pacific, which is compared with the simulated results from the rigid boundary model. Simulated results show that the both western North Pacific and eastern equatorial Pacific are two important sinks of anthropogenic CO2. larger isopycnal diffusivity produces larger exchange fluxes of anthropogenic CO2 in the western North Pacific but smaller fluxes in the equatorial region. Compared with the results from the rigid boundary model, the air-sea exchange flux of anthropogenic CO2 is larger in these two regions in the open boundary model. During the period 1800- 1997, the North Pacific has taken up 23.75 GtC of anthropogenic CO2 in RUN1. The subpolar region is an important export region of absorbed anthropogenic CO2, where 38 % - 54 % of the absorbed anthropogenic CO2 is transported to other regions, whereas the region of 20°N - 30°N is an important storing region, which amounts to 24% of the total storage in the North Pacific. The open boundary has a .significant impact on the uptake and storage of anthropogenie CO2 in the area south of 10°N. Compared with the data-based estimate, although the model underestimates the penetration of anthropogenie CO2 in the western North Pacific and overestimates the penetration in the eastern North Pacific, the model generally well estimates the storage of anthropogenie CO2 in the North Pacific.