An evaluation of tracer fields and anthropogenic carbon in the equatorial and the tropical North Atlantic
An evaluation of tracer fields and anthropogenic carbon in the equatorial and the tropical North Atlantic
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DOI：
10.1016/j.dsr.2012.05.007
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发表时间：
2012-09-01
影响因子：
2.4
通讯作者：
Wallace, D. W. R.
中科院分区：
文献类型：
--
作者：
Schneider, A.;Tanhua, T.;Wallace, D. W. R.
在2006年至2009年期间，将过境时间分布法应用于四次前往热带北大西洋的航行中二氯二氟甲烷和六氟化硫的测量，以估计人为碳（C-ant）浓度。通过假设过境时间分布的反高斯分布，获得了与数据的最佳拟合，平均年龄与宽度之比为1。赤道带（5°S-5°N）和几内亚穹丘区（5°N -15°N）的平均年龄和C-ant浓度存在显著差异。几内亚穹隆区的平均年龄比赤道带相同深度或密度的平均年龄高，C-ant浓度低。赤道带在1200 m以上的平均柱存量比几内亚穹隆地区高约3 mol m（-2）。在热带大西洋的整个水柱中，c -蚂蚁的平均柱存量为32.2 mol m(-2)（误差范围：30.6-45.2 mol m(-2)），这明显低于以前的估计。东热带大西洋的c -蚂蚁总库存为2.5 Pg（误差范围：2.3-3.5 Pg），面积为6 x 10(6) km(2)，包括几内亚穹丘地区和赤道带。赤道带的C-ant储量比几内亚穹球区高40%，这反映了赤道存在相对年轻的深水，人为碳含量高。我们基于示踪剂的c -蚂蚁估计值与1999年使用TrOCA方法计算的c -蚂蚁浓度进行了比较。基于TrOCA的估计明显高于我们基于示踪剂的C-ant估计。1999年与2006-2009年的示踪测量结果对比显示，上层水柱的通风可能加快，该深度范围内的c -蚂蚁浓度以更快的速度增加，热带地表水的c -蚂蚁增加了12.1 mu mol kg（-1）。(c) 2012 Elsevier Ltd.版权所有。
The transit time distribution method was applied to dichlorodifluoromethane and sulfur hexafluoride measurements from four cruises to the tropical North Atlantic between 2006 and 2009 in order to estimate anthropogenic carbon (C-ant) concentrations. By assuming an Inverse Gaussian distribution of the transit time distribution the best fit to the data was achieved with the ratio of mean age to width equals 1. Significant differences in the mean age and C-ant concentrations between the equatorial belt (5 degrees S-5 degrees N) and the Guinea dome area (5 degrees-15 degrees N) was found. Mean ages are higher and C-ant concentrations are lower in the Guinea dome area than at same depths, or densities, in the equatorial belt. The mean column inventories in the upper 1200 m are higher by about 3 mol m(-2) in the equatorial belt compared to the Guinea dome area. The mean column inventory of C-ant, for the whole water column, in the tropical Atlantic is 32.2 mol m(-2) (error range: 30.6-45.2 mol m(-2)), which is significantly lower than the previous estimates. The total C-ant inventory in the eastern tropical Atlantic is 2.5 Pg (error range: 2.3-3.5 Pg) for an area of 6 x 10(6) km(2), comprising the Guinea dome region and the equatorial belt. The equatorial belt has 40% higher storage of C-ant compared to the Guinea dome area which reflects the occurrence of relatively young deep waters at the equator, being high in anthropogenic carbon. Our tracer based C-ant estimates were compared to C-ant concentrations calculated with the TrOCA method applied to measurements conducted in 1999. The TrOCA based estimates are significantly higher than our tracer based C-ant estimates. Comparison between tracer measurements in 1999 and the 2006-2009 time-frame revealed possible speed-up of ventilation in the upper water column, increasing the C-ant concentration in this depth range at a faster rate and a C-ant increase of 12.1 mu mol kg(-1) in the tropical surface water was found. (c) 2012 Elsevier Ltd. All rights reserved.