Minimize Current Fronts

Back to Oceanic Phenomena

Current fronts become visible on SAR images through several mechanisms:

  1. The current shear at the boundary between the water masses having different velocities modulates the Bragg waves due to wave-current interaction
  2. The two water masses often have different temperatures which results in a smaller wind stress on the colder side where the boundary layer above the sea surface is more stable. Consequently the water surface is less rough on the colder side than on the warmer side of the front.
  3. Under a uniform wind field the velocity of the air relative to the water surface is different on both sides of the current front which also gives rise to different wind stresses at both sides of the front
  4. Material floating on the sea surface often accumulates at the front. This can, e.g., be biogenic surface films or sea grass, which also modifies the sea surface roughness.
Australia Australia

Latitude: 32° 10' N - Longitude: 153° 02' E

SAR strip of three ERS-1 SAR frames acquired over the coastal waters at the east coast of Australia. The East-Australian Current, which is the western boundary current of the South Pacific, is clearly visible as a broad bright band.

Noteworthy are the V-shaped features visible in the northern section of this image. Their origin is unknown to us.
Orbit Frame(s) Satellite Date Time Location
08019 4239-4257-4275 ERS-1 26-Jun-1993 23:43

If you have any comments on this image please write an e-mail to alpers@ifm.uni-hamburg.de.

References

  • Church, J.A. & Craig, P.D., Australia's shelf seas: Diversity and complexity (30,W-S). In: The Sea, 11, edited by A.R. Robinson and K.H. Brink, John Wiley & Sons, Inc., Chapter 33, 933-964 (1998).
  • Nilsson, C.S. & Tildesley, P.C., Imaging of oceanic fronts by ERS 1 synthetic aperture radar. J. Geophys. Res., 100, No. C1, 953-967 (1995).
  • Nilsson, C.S. & Cresswell, G.R., The formation and evolution of East Australian Current warm-core eddies. In: Progress in Oceanography. Vol. 9. (M.V. Angel and J. O'Brien, editors). Pergamon Press, Oxford, Frankfurt, pp. 133-183 (1982).