Antarctic Circumpolar Current response to zonally averaged winds
Gille, Sarah T.
Stevens, David P.
Tokmakian, Robin T.
Heywood, Karen J.
MetadataShow full item record
Coherence analysis techniques are used to compare Southern Ocean wind forcing with Antarctic Circumpolar Current transport. Winds are derived from five different products: ERS winds that have been bin-averaged, weekly gridded ERS winds produced by the Centre ERS d'Archivage et de Traitement, 5 day winds from the Special Sensor Microwave Imager, analysis winds from the European Centre for Medium-Range Weather Forecasts, and reanalysis winds from the National Centers for Environmental Prediction. Barotropic transport is estimated from the pressure difference between bottom pressure gauges deployed on either side of Drake Passage by Proudman Oceanographic Laboratory as part of the World Ocean Circulation Experiment. Surface transport is estimated from TOPEX altimetry. Results indicate that transport and wind forcing are coherent over a broad range of frequencies, corresponding to time periods of roughly 10-256 days. Highest coherences occur for winds at latitudes on the south side of Drake Passage. Barotropic ocean transport lags wind forcing not by a constant time interval but by a constant phase lag of about one eighteenth of a cycle at a broad range of frequencies, suggesting that the oceanic response to wind is controlled by both the tendency term and a frequency dependent viscous process. Surface transport lags by a longer phase interval. Wind stress curl north of Drake Passage is more coherent with transport than is wind stress curl in the latitudes of Drake Passage. Ocean transport lags wind stress curl, suggesting that transport fluctuations are not governed by a simple Sverdrupian vorticity balance. Like the observations, general circulation model transports from the Parallel Ocean Program and from the Parallel Ocean Climate Model are coherent with wind stress from the south side of Drake Passage and with wind stress curl from latitudes north of Drake Passage. Unlike the observations, model transport and bottom pressure vary almost simultaneously with the wind and do not replicate the observed phase lags, implying that the effective model viscosity may be too large.
Paper number 1999JC900333
Showing items related by title, author, creator and subject.
Semtner, Albert J. Jr.; Chervin, Robert M. (American Geophysical Union, 1992-04-15);A concerted effort has been made to simulate the global ocean circulation with resolved eddies, using a highly optimized model on the best available supercomputer. An earlier 20-year spin-up has been extended for 12.5 ...
Evolution of the stratospheric aerosol in the northern hemisphere following the June 1991 volcanic eruption of Mount Pinatubo: Role of tropospheric-stratospheric exchange and transport Jonsson, H.H.; Wilson, James, C.; Brock, Charles A.; Dye, J.E.; Ferry, G.V.; Chan, K.R. (1996-01);Since the eruption of Mount Pinatubo in June 1991, measurements of particle size and concentration have intermittently been carried out from an ER-2 aircraft at altitudes of up to 21 km at midlatitudes and high latitudes ...
Challenor, P.G.; Tokmakian, R.T. (1999);From in situ measurements it has been inferred that the variability of flow through the Drake Passage down to 250&n does not depend upon depth (barotropic flow). By making this assumption it is possible to calculate the ...