Observing deep convection in the Labrador Sea during winter 1994/95
Rez.: A 12-month mooring record (May 1994-June 1995), together with accompanying PALACE float data, is used to describe an annual cycle of deep convection and restratification in the Labrador Sea. The mooring is located at 56.75 degree N, 52.5 degree W, near the former site of Ocean Weather Station...
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| Veröffentlicht in: | Journal of physical oceanography |
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| Format: | UnknownFormat |
| Sprache: | eng |
| Veröffentlicht: |
1999
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Tag hinzufügen | Zusammenfassung: | Rez.: A 12-month mooring record (May 1994-June 1995), together with accompanying PALACE float data, is used to describe an annual cycle of deep convection and restratification in the Labrador Sea. The mooring is located at 56.75 degree N, 52.5 degree W, near the former site of Ocean Weather Station Bravo, in water of similar to 3500 m depth. This is a pilot experiment for climate monitoring, and also for studies of deep-convection dynamics. Mooring measurements include temperature (T), salinity (S), horizontal and vertical velocity, and acoustic measurement of surface winds. The floats made weekly temperature-salinity profiles between their drift level (near 1500 m) and the surface. With moderately strong cooling to the atmosphere ( similar to 300 W/m super(2) averaged from November to March), wintertime convection penetrated from the surface to about 1750 m, overcoming the stabilizing effect of upper-ocean low-salinity water. The water column restratifies rapidly after brief vertical homogenization (in potential density, salinity, and potential temperature). Both the rapid restratification and the energetic high-frequency variations of T and S observed at the mooring are suggestive of a convection depth that varies greatly with location. Lateral variations in T and S exist down to very small scales, and these remnants of convection decay (with e-folding time similar to 170 day) after convection ceases. Lateral variability at the scale of 100 km is verified by PALACE profiles. The Eulerian mooring effectively samples the convection in a mesoscale region of ocean as eddies sweep past it; the Lagrangian PALACE floats are complementary in sampling the geography of deep convection more widely. This laterally variable convection leaves the water column with significant vertical gradients most of the year. Convection followed by lateral mixing gives vertical salinity profiles the (misleading) appearance that a one-dimensional diffusive process is fluxing freshwater downw |
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| Beschreibung: | 34 |
| ISSN: | 0022-3670 |