The atmospheric boundary layer above the Agulhas current during alongcurrent winds

Citation
M. Rouault et al., The atmospheric boundary layer above the Agulhas current during alongcurrent winds, J PHYS OCEA, 30(1), 2000, pp. 40-50
Citations number
40
Categorie Soggetti
Aquatic Sciences","Earth Sciences
Journal title
JOURNAL OF PHYSICAL OCEANOGRAPHY
ISSN journal
00223670 → ACNP
Volume
30
Issue
1
Year of publication
2000
Pages
40 - 50
Database
ISI
SICI code
0022-3670(200001)30:1<40:TABLAT>2.0.ZU;2-V
Abstract
The response of the marine atmospheric boundary layer to the strong sea sur face temperature (SST) gradient across the warm Agulhas Current was studied in the Agulhas Current Air-Sea Exchange Experiment. south of Port Alfred, South Africa. Shipboard meteorological and oceanographic measurements and r adiosonde ascents are used to describe this response for wind regimes that are approximately parallel to the current. Surface hear fluxes increased by over 200 w m(-2) from the shelf to the current while the sensible heat flu x reversed sign. A characteristically stable boundary layer over the cool s helf waters was replaced by an unstable convective boundary layer over the current. The mean specific humidity and potential temperature of the bounda ry layer increased significantly over the current by 25% and 10% with a con comitant boundary layer deepening of 40 m (degrees C)(-1) SST In the presen ce of alongcurrent winds an atmospheric moisture and thermal front develope d over the inshore SST front, This is attributed to the horizontal gradient in the surface heat fluxes. The strong SST front owes its presence here to the juxtaposition of the warm current and an inshore kinematically driven subsurface upwelling cell whose surface expression is modulated by the wind stress.