18.104.22.168.6. Inverse barometer
The Inverse Barometer (IB) is the correction for variations in sea surface height due to atmospheric pressure variations (atmospheric loading). It can reach about ±15 cm and it is calculated from meteorological models.
Amplitude in metres of Inverse Barometer correction computed from ECMWF
atmospheric pressures during the Jason-1 cycle 223. This map is drawn using the Basic Radar Altimetry Toolbox from the Jason-1 GDR products. A Loess filter (value of 20) is applied to obtain a fully coloured plot but it makes some artificial data on coastal areas.
The response of the sea surface to changes in atmospheric pressure has a large effect on measured surface height. The simplest form for this correction is a purely local response of the sea surface to atmospheric pressure at the measurement point. The inverse barometer correction can be easily computed from the dry troposphere correction, by first computing sea level pressure Po:
IB (mm) = -9.948 * ( ΔRdry (mbars) - 1013.3 ) [from Aviso and PoDaac User Handbook - IGDR and GDR Jason-1 Product, 2008].
At a 1 mbar atmospheric pressure change corresponds to a linear response of the sea level about 1 cm.
- C. Wunsch and D. Stammer, Atmospheric loading and the oceanic inverted barometer effect, Reviews of Geophys., 35(1), 79-107, 1997.
- J. Willebrand, S.. Philander, R.. Pacanowski, The oceanic response to large-scale atmospheric disturbances, J. Phys.Oceanography 10, 411-429, 1980
- R.M. Ponte, P. Gaspar, Regional analysis of the inverted barometer effect over the global ocean using Topex/Poseidon data and model results, J. Geosphys. Res., 104 (C7), 15587-15601, 1999.
- D. Stammer, C. Wunsch, R.M. Ponte, De-aliasind of global high frequency barotropic motions in altimeter observations, Geosphys.Res.Lett., 27(8), 1175-1178, 2000.
- L. Carrère, F. Lyard, Modelling the barotropic response of the global ocean to atmospheric wind and pressure forcing - comparisons with observations , Geosphys.Res.Lett., 30(6), pp 1275, 2003.
All rights reserved, copyright © 2006-2011
Tutorial produced by CLS under contract to ESA and CNES