Analysis of the Guiana Abyssal Gyre Experiment [GAGE] Dataset

[0241505 .麦卡特尼]圭亚那深海环流实验（GAGE）在圭亚那盆地上放置了一组系泊的海流仪，以测量深海边界洋流，并试图探测和量化假想的向北流向其东部的洋流。在实施过程中，该阵列被放置在16°N处27个月，并通过与德国人的合作增强了GAGE。经向翻转变率试验。（MOVE，总部设在基尔大学）。GAGE/MOVE项目总共部署了10个系泊点，配备了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载CTD测量，以配合系泊部署和回收。GAGE在2002年5月完成了现场工作，除了一个GAGE系泊未能释放外，将于2003年3月恢复。对系泊仪器的初步观测结果证实了冈比亚深海环流假说。在北纬16度的深层西部边界流较强，估计为38 Sverdrups。在水文学和实测洋流中，它具有意想不到的两区结构：在1600米附近有一个向南流动强的陆上区，随着深度下降到4000米附近的弱流动；在3600-4600米附近有一个强流动区，在1600米附近向上减弱并逆转为向北流动。假设的向北再环流存在于三种情况中。紧靠近海并毗邻西部深层边界流，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，与大西洋中脊相邻，向北流动从海底5400米延伸到3600米。除深边界流中的一台外，整个盆地3600m及以下的所有阵列仪器均呈现北流。这就产生了一股令人惊讶的强大水流，被称为南极底水，最冷的深海水。这些向北的气流要素加在一起，初步估计为19-23个Sverdrups，产生15-19个Sverdrups的净输送，这是翻转环流冷分支的预期振幅。大型GAGE/MOVE数据集将与MOVE科学家合作完成。将测量到的水流和测量到的水文结合起来，产生16 N深流的完整定量表征，包括其振幅和结构的变化。在此基础上，对圭亚那盆地内的完整水文数据集进行了重新研究，以充分表征圭亚那深海环流，并确定其在经向翻转环流冷分支中的作用。

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.