Variations and trends of CO2 in the surface seawater in the Southern Ocean south of Australia between 1969 and 2002
Variations and trends of CO2 in the surface seawater in the Southern Ocean south of Australia between 1969 and 2002
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DOI：
10.3402/tellusb.v57i1.16773
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发表时间：
2005-01
期刊：
影响因子：
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通讯作者：
H. Yoshikawa‐Inoue;Masao Ishii
中科院分区：
文献类型：
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作者：
H. Yoshikawa‐Inoue;Masao Ishii
在1969年1月至2月、1983年12月至1984年1月、1994年12月至1995年1月和2002年1月的四次航行中，在澳大利亚以南的南大洋测量了表层海水中的CO2分压（pCOsw 2）。四次巡航的pCOsw 2的空间分布在亚南极锋（SAF）以北显示出相同的模式，而在SAF以南则出现了逐年变化。我们评估的pCOsw 2代表海洋锋之间的区域的长期趋势，考虑到pCOsw 2的季节变化和南半球的海表温度（SST）的长期增加的变化。观测到的pCOsw 2增长率最低为0.7 ± 0.1 µatm yr−1，在副热带锋（STF）以北15 °C的SST观测到，在STF和SAF之间的亚南极区（SAZ）观测到1.0 ± 0.5 µatm yr−1，SAF和极锋（PF）之间的极锋区（PFZ）为1.5 ± 0.4 µatm yr−1，PF和62°S之间的极区（PZ）为1.8 ± 0.2 µatm yr−1，根据表面盐度和卫星图像，确定为季节性海冰区（SSIZ）的北方边缘。这些增加是由于吸收人为CO2以及热力学温度效应、海洋迁移和生物活动的变化造成的。在62至66.5°S之间的SSIZ中，由于2002年1月生物活动导致二氧化碳显着下降，我们无法清楚地评估pCOsw 2的长期趋势。在STF附近和SAZ中pCOsw 2相对较低的增长率可能与在其各自的区域中形成亚热带模式水和亚南极模式水有关。在STF北部和PZ之间，总溶解无机碳的增长率通过缓冲因子计算为约0.5-0.8 µmol kg−1 yr−1。
Measurements of the partial pressure of CO2 in surface seawater (pCOsw2) were made in the Southern Ocean south of Australia during four cruises in January to February 1969, December 1983 to January 1984, December 1994 to January 1995 and January 2002. The spatial distribution of pCOsw2 for the four cruises showed the same pattern north of the Sub-Antarctic Front (SAF), while year-to-year changes were noted south of the SAF. We evaluated the long-term trend of the pCOsw2 representative of the zone between oceanographic fronts by taking into account changes in the seasonal variation in pCOsw2 and the long-term increase of the sea-surface temperature (SST) of the Southern Hemisphere. The observed growth rate of pCOsw2 was 0.7 ± 0.1 µatm yr−1 at its minimum, which was observed at the SST of 15 °C north of the Subtropical Front (STF), 1.0 ± 0.5 µatm yr−1 in the Sub-Antarctic Zone (SAZ) between STF and SAF, 1.5 ± 0.4 µatm yr−1 in the Polar Frontal Zone (PFZ) between SAF and the Polar Front (PF) and 1.8 ± 0.2 µatm yr−1 in the Polar Zone (PZ) between PF and 62°S, determined as the northern edge of the Seasonal Sea Ice Zone (SSIZ) on the basis of surface salinity and satellite images. These increases were caused by the uptake of anthropogenic CO2 as well as variations in the thermodynamic temperature effect, ocean transport and biological activity. In the SSIZ between 62 and 66.5°S, we could not clearly evaluate the long-term trend of pCOsw2 due to the remarkable CO2 drawdown due to biological activity in January 2002. The relatively low growth rates of pCOsw2 close to the STF and in the SAZ are probably associated with the formation of Subtropical Mode Water and Sub-Antarctic Mode Water in their respective zones. Between the north of the STF and the PZ, the growth rate of total dissolved inorganic carbon was calculated to be about 0.5–0.8 µmol kg−1 yr−1 via the buffer factor.