Vertical alignment of the Gulf Stream

• Published in: Tellus. Series A, Dynamic meteorology and oceanography Vol. 57; no. 4; pp. 691 - 700
• Main Authors: RATSIMANDRESY, A. W., PELEGRÍ, J. L.
• Format: Journal Article
• Language: English
• Published: 9600 Garsington Road , Oxford OX4 2DQ , UK , USA Munksgaard International Publishers 01.08.2005; Blackwell
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Marine; Physics of the oceans; Thermohaline structure and circulation. Turbulence and diffusion; North Atlantic; Gulf Stream; ANW, USA, North Carolina, Cape Hatteras; A, Atlantic, Gulf Stream; ocean currents; Adjustment(atmosphere, ocean); Alignment; density; Atlantic Ocean; Depth profile; Isentropic surface; Jet(atmosphere, ocean); Bathythermograph; Velocity distribution; Western boundary current; ocean circulation
• ISSN: 0280-6495; 1600-0870
• DOI: 10.1111/j.1600-0870.2005.00115.x

ABSTRACT A historical set of expendable bathythermograph (XBT) and Pegasus sections across the Gulf Stream in natural coordinates is examined to investigate the isopycnic structure of the current off Cape Hatteras. In isopycnic‐natural coordinates, the axis of the Stream remains vertically aligned, in contrast to its well‐known offshore tilting when plotted as a function of depth. These results are confirmed using the geostrophic velocities obtained from a synthetic temperature field for the Gulf Stream. We prove that a baroclinic current aligned with density cannot be aligned with depth, and vice versa, and we show that the density alignment of the Gulf Stream results from the distortion of the density field and has negligible dependence on the choice of reference level. The invariable character of intense geophysical jets is supported through analogous representations for the upper level atmospheric jet stream in isentropic coordinates. These show that the atmospheric jet, when plotted on to a section normal to the direction of its maximum velocity core, is vertically aligned with potential temperature.