Abstract's details
Validation of altimetry by using in situ observations of pressure and acoustic travel time in the Southern Ocean
CoAuthors
Event: 2022 Ocean Surface Topography Science Team Meeting
Session: Quantifying Errors and Uncertainties in Altimetry data
Presentation type: Type Poster
Contribution: PDF file
Abstract:
In large parts of the Southern Ocean stratification and dynamics are relatively uniform and allow the application of the “Gravest Empirical Mode” (GEM) concept. Among other characteristics, the concept describes how variations of heat content are linearly related to those of salt content and steric height. The slope of the function depends on the local stratification. Furthermore heat content variations are a function of vertical acoustic travel time. This leads to the conclusion that measuring ocean bottom pressure (OBP) and vertical travel time with pressure inverted echo sounders (PIES) allows us to calculate sea surface height anomalies. The concept has been developed during the Sub-Antarctic Flux and Dynamics Experiment (SAFDE) experiment south of Australia (Sun et al., 2001). Its validity has been confirmed south of Africa (Behnisch et al., 2013).
In previous studies GEM was primarily applied by using altimetry and learn about the stratification of the ocean. Here we turn the question around and try to use in situ observations to predict and explain altimetry using GEM. An array of 13 PIES deployed south of Africa was used to generate oceanic sea surface height variability estimates. These are compared to multi satellite altimetry analysis produced by AVISO, and along track estimates from the Radar Altimetry Database (RADS). We present variances, correlations and patterns of variability of the measured signals and their differences.
Sun, C., and D.R. Watts, 2001: A circumpolar gravest empirical mode for the Southern Ocean hydrography. J. Geophys. Res. - Oceans, 106, 2833-2855.
Behnisch, M. , Macrander, O. , Boebel, O. Wolff, J. O. and Schröter, J., 2013: Barotropic and deep‐referenced baroclinic SSH variability derived from Pressure Inverted Echo Sound-ers (PIES) south of Africa, Journal of Geophysical Research-Oceans, 118 (6), pp. 3046-3058. doi:10.1002/jgrc.
In previous studies GEM was primarily applied by using altimetry and learn about the stratification of the ocean. Here we turn the question around and try to use in situ observations to predict and explain altimetry using GEM. An array of 13 PIES deployed south of Africa was used to generate oceanic sea surface height variability estimates. These are compared to multi satellite altimetry analysis produced by AVISO, and along track estimates from the Radar Altimetry Database (RADS). We present variances, correlations and patterns of variability of the measured signals and their differences.
Sun, C., and D.R. Watts, 2001: A circumpolar gravest empirical mode for the Southern Ocean hydrography. J. Geophys. Res. - Oceans, 106, 2833-2855.
Behnisch, M. , Macrander, O. , Boebel, O. Wolff, J. O. and Schröter, J., 2013: Barotropic and deep‐referenced baroclinic SSH variability derived from Pressure Inverted Echo Sound-ers (PIES) south of Africa, Journal of Geophysical Research-Oceans, 118 (6), pp. 3046-3058. doi:10.1002/jgrc.