海洋对人为CO2吸收的三维模式研究

文中用包含海洋化学过程和一个简单生物过程的三维碳循环模式模拟了海洋对大气CO₂的吸收,并分析了碳吸收的纬度分布。模拟工业革命以来海洋对大气CO₂的吸收表明:海洋碳吸收再加上大气CO₂的增加只占由化石燃料燃烧、森林砍伐和土地利用的变化而释放到大气中的CO₂的2/3。1980～1989年期间海洋年平均吸收2.05GtC。海洋人为CO₂的吸收有明显的纬度特征。模式计算的海洋CO₂的吸收在总量与纬度分布上与观测结果比较相符。     

印度洋二维碳循环模式中表层CO2分压分布对物理和生化过程的敏感性试验

利用二维印度洋碳循环模式的模拟结果,集中对表层海洋中的CO2分压分布及其控制因子、海洋生物对海气CO2交换的影响、海洋营养物含量的改变和海洋环流的改变对大气CO2浓度的影响等进行了深入的分析和讨论,并与实际的GEOSECS观测数据的分析结果做比较;研究了与表层海洋CO2分压相关的海洋条件,较详细讨论了形成海洋表层CO2源与汇系统的决定因素及其相对重要性,得到了海洋热力因子和海洋环流对海洋表层的CO2化学过程起着决定性作用而生物过程仅处于次要地位的重要结论。此外,还利用建立的海洋碳模式进行了一些有意义的数值试验,详细讨论了海洋的物理化学因子改变对大气CO2浓度的可能影响。       

二维的大气CO2——大西洋碳循环模式

本文描述了一个二维（纬度×深度）的大西洋碳循环模式，模拟了大气和海洋间CO2的交换以及碳在海洋中的输送过程。模式在运行时使用了一个12层的三维动力学模拟的海洋环流的结果。大西洋被划分成397个网格箱，每个箱子中各种形式的碳的含量、总碱度、溶解的无机营养物和溶解氧的浓度以及几种14C(碳14)同位素的值分别得到求解。模式稳定状态的计算采用解大型稀疏线性方程组的直接解法。计算结果与“地球化学的海洋研究（GEOSECS）”的实际观测数据对比，表明模式较好地再现了实际大西洋中几种化学量的分布。     

带生物泵三维全球海洋碳循环模式

建立了一个带生物泵的三维全球海洋碳循环模式,该模式在海气界面上与一个CO2充分混合的大气箱进行CO2交换,模式积分1 200年达到准稳定态的海水总CO2、碱度及溶解氧的浓度、表层新生产力、海气分压差等的分布与实测相接近。通过带生物泵和不带生物泵的对比实验,表明海洋生物过程在海洋吸收大气中CO2能力上起着重要作用。     

海洋碳循环模式(Ⅱ)——对印度洋的模拟结果分析

把建好的海洋碳模式应用于印度洋区域，模拟得到了印度洋中与碳有关各化学量的表层分布、垂直分布和沿子午线面的等值线分布。与实测的GEOSECS(Geochemical Ocean－Section Study)数据作对比，模式较好地再现了印度洋上营养盐浓度、总碳浓度、总碱度和溶解氧的二维分布。通过模拟还发现，在稳定状态下，大气和海洋中总碳含量的分布依赖于发生在海洋中的各种物理化学过程及边界条件，水平扩散系数Kh和光合作用常数率Kg对各化学量的分布有较大影响(以前有学者认为不太重要，如Baes[1])；南印度洋中纬地区10°S至30°S是14C的重要向下渗透区域，人为排放的CO2可通过这片渗透区从海洋的表层输入海洋的深层。     

全球二氧化碳循环的一维模式研究

本文用一个全球碳循环的一维模式重建了1860年以来的大气二氧化碳浓度。结果表明:(1) 模拟结果与冒纳罗亚（Mauna Loa）的观测结果之间存在极好的一致性；(2) 海洋虽然是人类活动释放的CO2的最重要的汇，但其作为碳汇的能力受到海洋缓冲效应的限制。海洋吸收CO2的速率还与某些响应过程密切相关；(3) 在全球碳循环中，生态系统的作用是双重的:人类活动对它的破坏使它成为CO2的源，而其对过量CO2的响应又使其成为CO2的一个汇。工业革命以来，人类对生态系统的破坏与其自身的恢复大致是同量级的；(4) 陆地生物圈缩短了整个碳循环系统对人为扰动的响应时间。     

海洋碳循环模式（I）——一个包括海洋动力学环流、化学过程和生物过程的二维碳模式的建立

利用一个全球海洋动力学环流模式所模拟的海洋环流场,建立了一个全面的二维海洋碳循环模式。此模式摒弃了传统箱模式的缺陷,充分考虑了诸如大气与海洋间的碳交换、光合作用和氧化分解、碳酸钙的产生和溶解、悬浮颗粒物的下沉等过程,尤其是在模式中耦合进了以往甚少考虑的海洋生物过程对碳循环的影响,引入了详尽合理的参数化方案。通过模拟发现：在稳定状态下,大气和海洋中总碳含量分布依赖于发生在海洋中的各种物理化学过程及边界条件,水平扩散系数和光合作用常数率对各化学量的分布有很大影响。     

海洋碳循环模式（Ⅰ）一个包括海洋动力学环流、化学过程和生物过程的二维碳模式的建立

利用一个全球海洋动力学环流模式所模拟的海洋环流场,建立了一个全面的二维海洋碳循环模式。此模式摒弃了传统箱模式的缺陷,充分考虑了诸如大气与海洋间的碳交换、光合作用和氧化分解、碳酸钙的产生和溶解、悬浮颗粒物的下沉等过程,尤其是在模式中耦合进了以往甚少考虑的海洋生物过程对碳循环的影响,引入了详尽合理的参数化方案。通过模拟发现：在稳定状态下,大气和海洋中总碳含量分布依赖于发生在海洋中的各种物理化学过程及边界条件,水平扩散系数和光合作用常数率对各化学量的分布有很大影响。     

生物泵在海洋碳循环中的作用

生物过程在海洋碳的自然分布中起着重要的作用,它使海洋中碳的储量大大增加.作者用包含海洋化学过程和一个简单生物过程的三维碳循环模式模拟了生物泵在海洋碳循环中的作用.模式计算的结果表明:生物过程产生的海-气通量的量级非常大;在高纬度和赤道它的量级与因溶解度泵产生的碳的海-气通量差不多.在高纬度地区这两个通量符号相反,使组合模式中的通量大小比只有溶解度泵时的通量小,而在赤道两者的符号相同,使组合模式在赤道的通量大于只有溶解度泵时的通量.在稳态条件下生物泵对海洋吸收人为CO2的直接影响很小.     

一个地球系统模式模拟的气候变化对海洋碳循环的影响

使用维多利亚大学的地球系统模式进行模拟,选取1800-2500年间较高的CO₂浓度情景（RCP8.5）,分析由于CO₂增加引起的气候变化对海洋碳循环的影响。当气候敏感度为3.0 K时,相对于无气候变化,到2100年,由于大气CO₂增加造成的气候变化导致海表面温度升高2.7 K,北大西洋深水流量减少4.5 Sv,海洋对人为碳的年吸收减少0.8 Pg C;比较人为溶解无机碳在海洋中的垂直累积分布,发现气候变化对海洋吸收大气CO₂的影响在北大西洋区域最明显。1800-2500年,相对于不考虑气候变化的情景,模式模拟的气候变化导致整个海洋对人为碳的累积吸收总量减少23.1%,其中北大西洋减少32.0%。此外,比较不同气候敏感度（0～4.5 K,间隔为0.5 K）的模拟结果发现,气候敏感度越高,气候变化对海洋吸收CO₂能力的抑制作用越明显。     

A SIMULATION OF CO2 UPTAKE IN A THREE DIMENSIONAL OCEAN CARBON CYCLE MODEL*

A three-dimensional ocean carbon cycle model which is a general circulation model coupled with simple biogeochemical processes is used to simulate CO₂ uptake by the ocean.The OGCM used is a modified version of the Geophysical Fluid Dynamics Laboratory modular ocean model(MOM2).The ocean chemistry and a simple ocean biota model are included.Principal variablesare total CO₂,alkalinity and phosphate.The vertical profile of POC flux observed by sediment traps is adopted,the rain ratio,a ratio of production rate of calcite against that of POC,and the bio-production efficiency should be 0.06 and 2 per year,separately.The uptake of anthropogenic CO₂ by the ocean is studied.Calculated oceanic uptake of anthropogenic CO₂ during the 1980s is 2.05×10¹⁵g(Pg)per year.The regional distributions of global oceanic CO₂ are discussed.     

海洋中碳及营养物自然分布的数值模拟

用海洋生物化学环流模式（Ｂ－ ＧＣＭ） 模拟了工业化前碳及营养物在海洋中的分布, 并得到了较为合理的结果。模式考虑了海洋表面化学和一个简单的生物过程。模式的主要预报变量有总ＣＯ２ 、碱度和磷酸盐。决定生物化学物质分布的三个参数的取值为： ＰＯＣ 通量的垂直廓线的指数ａ 取观测值０－８５８ 、生物生产效率ｒ ＝ ２／ 年和下落比Ｒ＝ ０－０６ 。用Ｂ－ＧＣＭ 模拟出的结果与ＧＥＯＳＥＣＳ观测值基本相符。     

Estimates of Anthropogenic CO_2 Uptake in a Global Ocean Model

A global ocean general circulation model (L30T63) is employed to study the uptake and distribution of anthropogenic CO2 in the ocean. A subgrid-scale mixing scheme called GM90 is used in the model. There are two main GM90 parameters including isopycnal diffusivity and skew (thickness) diffusivity. Sensitivities of the ocean circulation and the redistribution of dissolved anthropogenic CO2 to these two parameters are examined. Two runs estimate the global oceanic anthropogenic CO2 uptake to be 1.64 and 1.73 ...     

A global ocean biogeochemistry general circulation model and its simulations

An ocean biogeochemistry model was developed and incorporated into a global ocean general circulation model (LICOM) to form an ocean biogeochemistry general circulation model (OBGCM). The model was used to study the natural carbon cycle and the uptake and storage of anthropogenic CO2 in the ocean. A global export production of 12.5 Pg C yr-1 was obtained. The model estimated that in the pre-industrial era the global equatorial region within 15o of the equator released 0.97 Pg C yr-1 to the atmosphere, which was balanced by the gain of CO2 in other regions. The post-industrial air-sea CO2 flux indicated the oceanic uptake of CO2 emitted by human activities. An increase of 20－50 mol kg-1 for surface dissolved inorganic carbon (DIC) concentrations in the 1990s relative to pre-industrial times was obtained in the simulation, which was consistent with data-based estimates. The model generated a total anthropogenic carbon inventory of 105 Pg C as of 1994, which was within the range of estimates by other researchers. Various transports of both natural and anthropogenic DIC as well as labile dissolved organic carbon (LDOC) were estimated from the simulation. It was realized that the Southern Ocean and the high-latitude region of the North Pacific are important export regions where accumulative air-sea CO2 fluxes are larger than the DIC inventory, whereas the subtropical regions are acceptance regions. The interhemispheric transport of total natural carbon (DIC+LDOC) was found to be northward (0.11 Pg C yr-1), which was just balanced by the gain of carbon from the atmosphere in the Southern Hemisphere.     

A two-dimensional zonally averaged ocean carbon cycle model

An ocean carbon cycle model driven by a constant flow field produced by a two-dimensional thermohaline circu-lation model is developed. Assuming that the biogenic carbon in the oceans is in a dynamic equilibrium, the inorganic carbon cycle is investigated. Before the oceanic uptake of CO2 is carried out, the investigation of 14C distributions in the oceans, including natural and bomb-produced 14C, is conducted by using different values of the exchange coefficient of CO2 for different flow fields (different vertical diffusivities) to test the performance of the model. The suitable values of the exchange coefficient and vertical diffusivities are chosen for the carbon cycle model. Under the forcing of given preindustrial atmospheric CO2 concentration of 280 ppmv, the carbon cycle model is integrated for seven thousand years to reach a steady state. For the human perturbation, two methods including the prescribed at-mospheric pCO2 and prescribed industrial emissions are used in this work. The results from the prescribed atmospher-ic pCO2 show that the oceans take up 36% of carbon dioxide released by human activities for the period of 1980-1989, while the results from the prescribed industrial emission rates show that the oceans take up 34% of car-bon dioxide emitted by industrial sources for the same period. By using the simple method of subtracting industrial emission rate from the total atmosphere+ocean accumulating rate, it can be deduced that before industrial revolution a non-industrial source exists, while after 1940 an extra sink is needed, and that a total non-industrial source of 45 GtC is obtained for the period of 1790-1990.     

IPCC确定的几种未来大气CO2浓度水平对人为CO2排放的限制

用三维海洋碳循环模式和一个简单的陆地生物圈模式计算了IPCC(政府间气候变化委员会)未来大气CO2情景中海洋和生物圈的吸收,并结合土地变化的资料得出燃料的排放值。结果表明：尽管在所有的构想下,为了使大气中CO2浓度达到稳定必须减少排放,但对应不同的IPCC未来大气CO2情景,对人为CO2排放的限制是很不相同的。     

Simulation of ~(14)C in IAP/LASG L30T63 Ocean Model

1. Introduction14C is a radioactive isotope of carbon, whose halftime is about 5730 yr. Under natural circumstance,14C comes into being in the stratosphere because of thenitrogen explosion of cosmic radial. 14C is mixed inthe atmosphere, absorbed by oceans, and then trans-ported into deep ocean. 14C radioactively reduces asits age increases. The reduction process of 14C canuncover the evolvement process of sea water's age andrenewal time.14 C content is usually described with one in athousan…     

Estimates of anthropogenic CO<Subscript>2</Subscript> uptake in a global ocean model

A global ocean general circulation model (L30T63) is employed to study the uptake and distribution of anthropogenic CO₂ in the ocean. A subgrid-scale mixing scheme called GM90 is used in the model. There are two main GM90 parameters including isopycnal diffusivity and skew (thickness) diffusivity. Sensitivities of the ocean circulation and the redistribution of dissolved anthropogenic CO₂ to these two parameters are examined. Two runs estimate the global oceanic anthropogenic CO₂ uptake to be 1.64 and 1.73 Pg C yr^-1 for the 1990s, and that the global ocean contained 86.8 and 92.7 Pg C of anthropogenic CO₂ at the end of 1994, respectively. Both the total inventory and uptake from our model are smaller than the data-based estimates. In this presentation, the vertical distributions of anthropogenic CO₂ at three meridional sections are discussed and compared with the available data-based estimates. The inventory in the individual basins is also calculated. Use of large isopycnal diffusivity can generally improve the simulated results, including the exchange flux, the vertical distribution patterns, inventory, storage, etc. In terms of comparison of the vertical distributions and column inventory, we find that the total inventory in the Pacific Ocean obtained from our model is in good agreement with the data-based estimate, but a large difference exists in the Atlantic Ocean, particularly in the South Atlantic. The main reasons are weak vertical mixing and that our model generates small exchange fluxes of anthropogenic CO₂ in the Southern Ocean. Improvement in the simulation of the vertical transport and sea ice in the Southern Ocean is important in future work.