2019-03-24T16:29:10Z
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oai:digital.csic.es:10261/129737
2019-03-05T13:16:06Z
com_10261_123
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col_10261_376
Diagnosing Mesoscale Vertical Motion from Horizontal Velocity and Density Data
Pallàs-Sanz, Enric
Viúdez, Álvaro
19 pages, 22 figures, 1 appendix
The mesoscale vertical velocity is obtained by solving a generalized omega equation (ω equation) using density and horizontal velocity data from three consecutive quasi-synoptic high-resolution surveys in the Alboran Sea. The Atlantic Jet (AJ) and the northern part of the Western Alboran Gyre (WAG) were observed as a large density anticyclonic front extending down to 200-230 m. The horizontal velocity uh in the AJ reached maxima of 1.2 m s-1 for the three surveys, with extreme Rossby numbers of ζ/f ≈ -0.9 in the WAG and +0.9 in the AJ (where ζ is the vertical vorticity and f is the Coriolis parameter). The generalized ω equation includes the ageostrophic horizontal flow. It is found that the most important >forcing> term in this equation is (fζph + ∇h e) · ∇h 2uh, where ζ ph is the horizontal (pseudo) vorticity and e is the buoyancy. This term is related to the horizontal advection of vertical vorticity by the vertical shear velocity, uhz · ∇hζ. Extreme values of the diagnosed vertical velocity w were located at 80-100 m with max[w] ⊂ [34, 45] and min{w} ⊂ [-64, -34] m day-1. Comparison with the quasigeostrophic (QG) ω equation shows that, because of the large Rossby numbers, non-QG terms are important. The differences between w and the QG vertical velocity are mainly related to the divergence of the ageostrophic part of the total Q vector (Qh ≡ ∇ huh · ∇h e) in the ω equation. © 2005 American Meteorological Society
Peer Reviewed
2005-10
2016-03-04T07:53:59Z
Artículo
doi: 10.1175/JPO2784.1
issn: 0022-3670
e-issn: 1520-0485
Journal of Physical Oceanography 35(10): 1744-1762 (2005)
10261/129737
10.1175/JPO2784.1
eng
Publisher's version
http://dx.doi.org/10.1175/JPO2784.1
Sí
openAccess
https://www2.ametsoc.org/ams/index.cfm/publications/authors/journal-and-bams-authors/author-resources/copyright-information/copyright-policy/
American Meteorological Society