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Estimation of Mean Dynamic Height from Altimeter Profiles and Hydrography

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  • 1 National Institute of Water and Atmospheric Research, Kilbirnie, Wellington, New Zealand
  • | 2 James Rennell Division for Ocean Circulation, Southampton Oceanography Centre, Southampton, United Kingdom
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Abstract

The mean dynamic height of the ocean surface is estimated along a subsatellite track of TOPEX/Poseidon crossing the East Auckland Current system northeast of New Zealand. Repeated hydrographic surveys along the track, together with surface elevation anomalies deduced from TOPEX altimeter data, enable four independent estimates of the mean dynamic height. From these estimates a more stable mean is calculated in which the uncertainty is estimated as less than 5 cm. The result can be applied as a reference profile for calibrating a long series of TOPEX passes so that cross-track geostrophic currents can be calculated. The scatter in the individual estimates indicates sufficient sampling variability to caution against using single hydrographic surveys as a basis for calibrating the satellite data.

Corresponding author address: Dr. Andrew K. Laing, NIWA Ltd., 301 Evans Bay Parade, Greta Point, P.O. Box 14-901, Kilbirnie, Wellington 14-901, New Zealand.

Email: a.laing@niwa.cri.nz

Abstract

The mean dynamic height of the ocean surface is estimated along a subsatellite track of TOPEX/Poseidon crossing the East Auckland Current system northeast of New Zealand. Repeated hydrographic surveys along the track, together with surface elevation anomalies deduced from TOPEX altimeter data, enable four independent estimates of the mean dynamic height. From these estimates a more stable mean is calculated in which the uncertainty is estimated as less than 5 cm. The result can be applied as a reference profile for calibrating a long series of TOPEX passes so that cross-track geostrophic currents can be calculated. The scatter in the individual estimates indicates sufficient sampling variability to caution against using single hydrographic surveys as a basis for calibrating the satellite data.

Corresponding author address: Dr. Andrew K. Laing, NIWA Ltd., 301 Evans Bay Parade, Greta Point, P.O. Box 14-901, Kilbirnie, Wellington 14-901, New Zealand.

Email: a.laing@niwa.cri.nz

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