Gulf Stream Upper Ocean Studies

在离开哈特拉斯角后不久，墨西哥湾流的输送量增加到150 SV以上，是佛罗里达流的五倍多，这是内部斯维德鲁普平衡所必需的。对于造成输送增加的再循环系统的结构或其变异性的性质所知甚少。海面上的高度计测量表明，变化的频谱是多种多样的，包括墨西哥湾流中快速的、可能是正压的变化，其时间尺度为一个月或更短，到年际变化，可能是正压的，也可能是斜压的，后者与质量场有关。我们建议将墨西哥湾流的重复船载测量（主要使用XBT和声学多普勒剖面）与卫星红外图像和GEOSAT高度计数据相结合，研究这一时间尺度范围。船上的测量将对墨西哥湾流系统及其垂直结构在800米深处的快速变化提供一些估计，特别强调从科德角以南的大陆架到百慕大的一条线。结合船上数据的不同子集的反向计算可以评估快速变率模式对该地区大规模预算的最终解决方案的影响程度。在墨西哥湾暖流到达其位置和运输的气候极端的时候，计划进行两次巡航，每次持续17天。与高度计数据一起，每次巡航都将提供一个独立的地面大地水准面估计值，沿着与GEOSAT高度计相一致的轨道，以及巡航时墨西哥湾流系统的三维结构。高程测量将用于扩展巡航的空间和时间采样，以涵盖曲流和年/年际变化的尺度。所采用的方法类似于海洋环流地形实验（TOPEX和法国POSEIDON）和世界海洋环流实验（WOCE）期间的现场数据。

Soon after it leaves Cape Hatteras, the Gulf Stream transport increases to values in excess of 150 SV, over five times that of the Flordia Current and what is necessary for the interior Sverdrup balance. Little is known about the structure of the recirculation regime responsible for the transport increase or the nature of its variability. Altimeter measurements at the sea surface suggest that the spectrum of variability is brood, encompassing rapid, possibly barotropic shifts in the Gulf Stream with time scales of order a month or less, to annual and interannual variations, which may be both barotropic and baroclinic, the latter associated with the field of mass. We propose to investigate this range of time scales by combining repeated shipboard measurements of the Gulf Stream, mainly using XBT and acoustic Doppler sections, with satellite infraed images and GEOSAT altimeter data. The shipbopard measurements will provide some estimates of the rapid variability of the Gulf Stream system and its vertical structure to depths of 800 m with special emphasis on a line from the continental shelfff south of the Cape Cod to Bermuda. Inverse calculations combining varying subsets of the shipboard data can assess the degree to which the rapid mode of variability affects resulting solutions for mass budgets of the region. Two cruises are envisioned, each of 17-day duration, at times of the year when the Gulf Stream reaches its climatological exetrmes of position and transport. Together with the altimeter data, each cruise will provide an independent estimate of the surface geoid along a track coincident with the GEOSAT altimeter as well as the three dimensional structure of the Gulf Stream system at the time of the cruises. The altimetric measurements will be used to extend the spatial and temproal sampling from the cruises to encompass scales of meanders and annual/interannual variability. The methods employed are analogous to those envisioned for the Topography Experiment for Ocean Circulation (TOPEX and French POSEIDON) and in situ data during the World Ocean Circulation Experiment (WOCE).