Analysis of the Guiana Abyssal Gyre Experiment [GAGE] Dataset

0241505麦卡特尼圭亚那深海回转实验(GAGE)在圭亚那盆地放置了一组系泊的海流计，以测量深层边界流，并试图探测和量化假设的向东向北的流。在实施时，阵列放置在16 N，持续27个月，Gage通过与德国的子午线颠覆可变性实验合作进行增强。(Move，总部设在英国基尔大学)。Gage/Move计划总共部署了10个系泊设备，72个海流计(测量温度和海流)和48个系泊温度/盐度仪器(CTD)。在圭亚那盆地进行了大量的船上CTD测量，同时进行了系泊部署和回收。Gage于2002年5月完成了现场工作，但有一艘Gage系泊设备未能解锁，将于2003年3月找回。首先看一看系泊仪器的结果，证实了冈比亚深海回旋假说。北纬16度的深层西部边界流很强，估计有38个斯维尔德鲁普。在水文地理学和实测流上，它有一个出人意料的两种流型结构：岸上流型在1600m附近有强南向流，在4000m附近随深度下降到弱流；近海流型在3600-4600m附近有强流，强度向上下降，在1600m处反转为北向流。紧邻西部深水边界流的近海，1600米至5400米之间的整个水柱向北流动。在圭亚那盆地的另一侧，毗邻中大西洋海脊，向北流动从5400米到3600米的海底延伸。所有横跨盆地的阵列仪器在3600米或更低的地方，除了一个在深边界流中的仪器外，都显示出向北的流动。这产生了一股令人惊讶的强劲水流，即所谓的南极底层水，这是最冷的深海水。这些向北的流动要素加在一起，初步估计为19-23个斯维尔德鲁普，产生15-19个斯维尔德鲁普的净输送，这是翻转环流冷端的预期幅度。大型的Gage/Move数据集将与MOVE科学家合作进行研究。测量的海流和测量的水文图将结合在一起，以产生16北纬的深水流动的完整定量特征，包括其幅度和结构的变化。有了这一强大的限制，将重新审查圭亚那盆地内的完整水文数据集，以充分描述圭亚那深海环流的特征，并确定其在经向翻转环流的寒冷部分中的作用。

0241505 McCartneyThe Guiana Abyssal Gyre Experiment (GAGE) placed a moored array of current meters across the Guiana Basin, to measure the deep boundary current and to attempt to detect and quantify the hypothesized northward flow to its east. As implemented the array was placed at 16 N for 27 months, and GAGE was enhanced through collaboration with a German .Meridional Overturning Variability Experiment. (MOVE, based at U. Kiel). Together the GAGE/MOVE program fielded 10 moorings with 72 current meters (measuring temperatures and currents) and 48 moored temperature/salinity instruments (CTDs). Considerable shipboard CTD measurements were made in the Guiana Basin in concert with mooring deployments and recoveries. GAGE completed its fieldwork in May 2002, with the exception of one GAGE mooring that failed to release and will be recovered in March of 2003. A first look at the results from the moored instruments, confirms the Gambia Abyssal Gyre hypothesis. The deep western boundary current at 16 N is strong, estimated as 38 Sverdrups. It has an unexpected two-regime structure in hydrography and in measured currents: an onshore regime with strong southward flow near 1600 m, declining with depth to weak flow near 4000 m, and an offshore regime with strong flow near 3600-4600 m, declining in strength upwards and reversing to northward flow at 1600 m. The hypothesized northward recirculation is found in three regimes. Immediately offshore and adjacent to the deep western boundary current the entire water column between 1600 m and 5400 m flows northward. On the opposite side of the Guiana Basin adjacent to the Mid-Atlantic Ridge northward flow extends from the seafloor at 5400 m to 3600 m. All array instruments across the Basin at or below 3600 m, except one in the deep boundary current, exhibit northward flow. This yields a surprisingly strong flow of what is called Antarctic Bottom Water, the coldest abyssal water. Together these northward flow elements are preliminarily estimated as 19-23 Sverdrups, yielding a net transport of 15-19 Sverdrups, the expected amplitude for the cold limb of the overturning circulation. The large GAGE/MOVE datasets will be worked up in collaboration with the MOVE scientists. The measured currents and the measured hydrography will be combined to produce a complete quantitative characterization of deep flow at 16 N, including its variabilities in amplitude and structure. With that as a powerful constraint, the full hydrographic dataset within the Guiana Basin will be reexamined to fully characterize the Guiana Abyssal Gyre and establish its role in the cold limb of the meridional overturning circulation.