【作者】 许苏清；

【导师】 陈立奇；

【作者基本信息】 厦门大学 ， 海洋化学， 2008， 博士

【摘要】 南大洋在全球碳循环自然源和人为源CO₂与大气之间的交换中起着关键的作用。本研究选取了中国南极科学考察第16航次和第21航次在两个航次相应时间内（1999年12月～2000年1月,2004年12月～2005年1月）,在中山站和长城站往返航线覆盖的海域,为50°S到75°S,60°W到80°E之间的南极海域。通过分析南大洋表层海水pCO₂时空变异的主要调控因子,利用雪龙船现场走航观测的海表层水pCO₂和叶绿素,海表层水水温数据,推导出pCO₂与调控因子之间的经验关系。根据遥感叶绿素和SST数据推导出研究海区的pCO₂数据,并利用从QuikSCAT卫星遥感风速数据得到海气交换系数K,AVHRR卫星遥感海表层水水温数据和由NOAA全球海洋数据中心提供的大气CO₂观测数据,海表层水盐度数据,建立一维网格模型,进一步估算该海区的海气碳通量周平均和月平均变化情况。从大面积宏观的角度上分析了南极海域夏季碳通量时空分布的区域特征,并且从定量上提高了南极海域对CO₂吸收的精确性。从模式计算的结果分析了南极海域不同海区pCO₂的调控因子。主要结果如下:1.南极海域夏季叶绿素浓度分布呈现随时间变化的向岸梯度分布的特征。在南半球高生产力季节的12月份和1月份,叶绿素高值区主要出现在冰边缘,岛屿附近和陆架海域。南极海域夏季水温由南向北呈现明显的随时间变化梯度递增分布趋势。在南极辐散带（73°E,64°S）和0经度断面上（0°E,65.5°S）两处有明显的SST涌升高值区。南极海域夏季表层水盐度的分布呈现不规则的空间分布,盐度值或高或低的块状分布。在1月份,表层海水盐度值有所下降。南极海域夏季为全年风场最弱的季节,在整个40°S以南海域以偏西风为主。2.南极海域60°W到80°E之间海区夏季基本是大气CO₂的净汇区,pCO₂的分布特征具有明显的时空变异。CO₂的源汇强弱情况为:南大西洋＞南乔治亚岛和马尔维纳斯群岛＞南极半岛＞普里兹湾湾内＞南印度洋＞威德尔海＞普里兹湾湾外。3.本研究计算得出在1999年12月份,2000年1月份,2004年12月份和2005年1月,50°S以南的南极海域碳吸收能力分别为:0.068GtC,0.072GtC,0.071 GtC,0.074 GtC。并估算出在1999年,2000年,2004年和2005年,南极海域年平均碳吸收能力为:0.476 GtC,0.489 GtC,0.511GtC,0.518 GtC。南极海域对大气CO₂吸收的贡献为25%。南极海域对大气CO₂的吸收呈逐年增加趋势。在威德尔海,南乔治亚岛、马尔维纳斯群岛和南极半岛,南大西洋海区的碳吸收能力逐年增加,是大气CO₂的强汇区,而南印度洋海区的碳吸收能力却呈下降趋势。更多还原

【Abstract】 The southern ocean plays a key role in the exchange process with atmosphere of natural and anthropogenic CO₂.In this study,we applied remote sensing data in comparison with the in situ investigation data to quantitatively express air-sea fluxes of pCO₂ in the region,from 50°S to 75°S and from 60°W to 80°E in the Southern Ocean.The empirical relationships between underway measured pCO₂ and shipboard Chl-a,sea surface temperature（SST） on board RV Xuelong were used to calibrate Chl-a and SST to create pCO₂ field in the remotely sensing datasets.Weekly and monthly maps of the air-sea CO₂ flux in the interested regions were further developed using the remotely sensed wind speed data from QuikSCAT dependence of the CO₂ gas transfer velocity of Wanninkhof,remotely sensed SST data from AVHRR and observed marine salinity data,atmospheric CO₂ data offered by the World Ocean Atlas by NOAA during the period CHINARE（Chinese Antarctic Research Expeditions）-ⅩⅥ（1999.12～2000.1） and CHINARE-ⅩⅪ（2004.12～2005.1） respectively.The results show regional spatial and temporal variabilities of air-sea flux of pCO2 in the Southern Ocean（south of 50°S） in the austral summer,and improve the accuracy of estimating the uptake of atmospheric CO₂ in the Southern OceanResults can be mainly summarized as the followings:1.The result reveals the pattern of chlorophyll accumulation gradiently alongshore over the summer,with lower concentrations offshore.Large phytoplankton blooms occur particularly in waters around ice edges and islands as well as in polynyas and continental shelves.Sea surface temperature increases gradiently from south to north associated with time when summer coming.The strongest upwelling of the Circumpolar Deep Water is expected to occur at the Antarctic Divergence（73°E,64°S） and in the region center with（0°E,65.5°S）.The sea surface salinity shows an irregular spatial patch distribution with higher or lower value.In January,the sea surface salinity decreases for the melted fresh water.In the austral summer,wind speed 10 meters above the sea surface turn to the lowest in the whole year.West wind is dominant in the austral summer south of 40°S in the southem ocean.2.The waters from 60°W to 80°E in the Southern Ocean is a sink of CO₂ from atmosphere during austral summer,pCO₂ distribution shows spatial and temperal variability.The sink magnitude can be sequenced as:the south Atlantic sector＞south Georgia and the Falkland island＞the Antarctic peninsula＞inner part of the Prydz bay＞south Indian sector＞Weddell sea＞outer part of the Prydz Bay.3.Using a model of CO₂ flux,the net uptake of atmospheric CO₂ in the Antarctic Ocean is 0.068GtC,0.072 GtC,0.071 GtC,0.074 GtC in Dec,1999, Jan,2000,Dec,2004 and Jan,2005 respectively.The annual net uptake in the Antarctic Ocean is 0.476 GtC,0.489 GtC,0.511 GtC,0.518 GtC in 1999, 2000,2004 and 2005 respectively,which contributes 25%to the total uptake in the global ocean.The net uptake of CO₂ in the Antarctic Ocean increases annually especially in the region as a strong sink,the Weddell sea,south Georgia,Falkland islands,the Antarctic Peninsula and the south Atlantic sector,while in the south Indian sector,the net uptake of CO₂ decreases.更多还原