Velocities continued

Our GEM's are look-up maps relating tau800 values to water column profiles of T and specific volume anomaly. They cannot be directly used with the IES data because an IES measures fluctuations in tau (designated tau') referenced to the bottom, instead of total tau referenced to 800 dbar.

We use the hydrographic data for converting both bottom-referenced tau' to tau'800, and tau'800 to tau800. High correlation between tau values for various pressure levels allow calculation, from the hydrographic data, of coefficients to convert the bottom-referenced tau' to tau'800 (figure). At a given IES site, all local (i.e., within 10 km) hydrocasts taken during the IES operation time were used to compute values of total tau800 at the times of these hydrocasts. By offsetting the IES tau800 time series to minimize the squared difference between these hydrographic tau800 and the simultaneous IES tau'800 values, we obtained the desired IES tau800 time series. tau800 mean values for each mooring were calculated from these time series (figure).

After these conversions, the IES data can be directly used with the GEM maps. Time series of specific volume anomaly sections were found by applying the specific volume anomaly GEM to the IES tau800 time series. Using the geostrophic method, a relative-velocity section time series was then derived from this specific volume anomaly section time series. A correspondingly located T section time series was found by averaging IES tau800 time series between adjacent IES sites and applying the T GEM to these averages.

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Abstract

Introduction

Dynamic Heights

Velocities

Transports

Conclusions

References

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