A study of currents in the Southern Ocean using satellite altimeter and model data

• Main Author: Snaith, Helen Mary
• Format: Thesis
• Language: English
• Published: University of Southampton 1992
• Subjects: Antarctic; Southern Ocean; The Antarctic; Pacific; Antarc*
• Online Access: https://eprints.soton.ac.uk/461961/; https://eprints.soton.ac.uk/461961/1/368547.pdf

The aims of the project are outlined and the satellite altimeter is introduced as a new method for the physical oceanographer to study ocean dynamics. The principles of the satellite altimeter are explained and a description of the sources of error found in the data is given, together with two possible methods for removal of residual errors. The principles of primitive equation ocean circulation models are outlined and the Fine Resolution Antarctic Model (FRAM) is introduced. Methods of hydrographic data collection are discussed and historical data on the circulation of the Southern Ocean are reviewed. The methods for Geosat data extraction, quality control and error correction used in the study are discussed. Data processed by collinear techniques have been used to obtain height profiles along tracks in two regions of the Southern Ocean; South of Africa and in the Central South Pacific. Mesoscale variability fields calculated from the along track altimeter data are presented and explained in terms of historical in situ current data and bottom topography. Geostrophic current speeds calculated from the residual height profiles yield velocity anomalies of the order of 20 cm s"1 for the Antarctic Circumpolar Current (ACC) and up to 1.38 m s1 for the Agulhas Current System, similar to values obtained by in situ measurements. Autocorrelation function calculations show that the characteristic length scales of height anomalies in the ACC are smaller than those of the Agulhas Current System. The FRAM data set is used as a source of artificial sea surface heights to give model altimeter data which are processed and analyzed for the Geosat study regions. The resultant variability fields are compared with the Geosat results. The effects of Geosat's sampling strategy and altimeter processing on the FRAM data are analyzed and are given as an indication of the possible reliability of Geosat variability fields. The results of feature recognition and autocorrelation function analyses are compared to those from Geosat both as a ...