ATLAS/TOPEX POSEIDON MOORINGS - SEACAT AND MINI- TEMPERATURE RECORDER DATA

J. Picaut (ORSTOM, New Caledonia)

Announced availability: 1 May 1994

Data Access

SeaCat and Mini-Temperature Recorder (MTR) data for two Atlas moorings located at TOPEX/POSEIDON cross-over points are available from the COARE Moored Data Archive at NOAA/PMEL's Tropical Atmosphere-Ocean Array (TAO) Project Office, (http://www.pmel.noaa.gov/coare/coare-data.html), along with other COARE mooring data.

The original data have also been archived at NOAA's National Oceanographic Data Center (NODC) in Silver Spring, Maryland (http://www.nodc.noaa.gov), the repository for COARE oceanographic data, and at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado (http://dss.ucar.edu/pub/toga_coare/), the site of the TOGA COARE deep archive.

Background

During the verification phase of the TOPEX/POSEIDON radar altimeter mission a rigorous open-ocean validation experiment was conducted in the western equatorial Pacific ocean. From August/September 1992 to February/March 1993, two TOGA-TAO moorings at 2S 156E (1739 m depth) and 2S, 164.4E (4400 m depth) were enhanced with additional temperature, conductivity and pressure sensors to measure precisely the dynamic height from the surface to the bottom at 5 min intervals directly beneath two TOPEX/POSEIDON crossovers.

Enhanced instrumentation on the Atlas mooring at 2S 156E included 16 Seacats (SB-16, two with pressure sensors), 5 MTRs, and 1 Aanderaa recorder (pressure and temperature). At 2S 164.4E, 11 Seacats (two with pressure sensors), 12 MTRs, and 2 Aanderaa recorders were added.

Enhanced bottom measurements were made within one mile of each Atlas. One Bottom Pressure Recorder (BPR) and two IES were located near 2S 156E and one BPR and one IES near 2S 164.4E.

Data File Information

SeaCat and MTR data are sampled every 5 min. Some SeaCats have an original sample rate of 10, 20 or 30 min; all have been interpolated every 5 min (see technical report).

The reference time at 2S-156E is 12 September 1992 at 8h00 (time=1); the reference time at 2S-164E is 26 August 1992 at 3h00 (time=1).

For seacat files, data are either interpolated at a fixed depth (*pf files) or not (*pv).

To read the data, the file format is: 

>seacat files:
>      k=1
>  12  read (10+i,*,end=1111) time,temperature,salinity,pressure
>      k=k+1
>      goto12
> 1111 continue
>       k=k-1
>
> mtr  files:
>      k=1
>  12  read (10+i,*,end=1111) time,temperature,pressure
>      k=k+1
>      goto12
> 1111 continue
>      k=k-1

Data Acquisition, Processing and Calibration

SeaCat data were recorded internally on RAM in ASCII format. Data from 26 SeaCats were processed at ORSTOM, Noumea and the University of Hawaii. Please note that along the 2S, 156E line, no data were returned by one SEACAT (45 m), and two series were interrupted after two months of measurements (5 m and 30 m). Along the 2S, 164 24'E line, one series was interrupted after two months (137 m) and the temperature sensor of the SeaCat at 400 m failed after one month. All Aanderaa data were lost due to a battery drain problem.

Pre- and post-calibrations were performed by the manufacturer (SeaBird Inc.) for all SeaCats.

MTR data were also recorded internally on RAM in ASCII format. No data were returned by two of the 17 MTRs deployed. The 15 remaining MTRs were originally processed at PMEL/NOAA and transferred to Noumea for further processing. Root mean square (RMS) differences between pre- and post-deployment calibrations were 0.006 deg C.

For more information, please contact:

Joel Picaut
Centre ORSTOM de Noumea
Groupe SURTROPAC
BP A5
Noumea Cedex
New Caledonia

email: picaut@noumea.orstom.nc
Phone: (68) 726-3243
FAX: (68) 726-4326

Reference

Gourdeau, L., J. Picaut, M.J. Langlade, A. Busalacchi, E. Hackert, M. McPhaden, P. Freitag, F. Gonzalez, M. Eble, R. Weller, 1995: Traitements des donnees pour la validation en plein ocean du niveau de la mer de TOPEX/POSEIDON dans le Pacifique equatorial ouest (Data preparation for the open-ocean validation of TOPEX/POSEIDON sea level in the western equatorial Pacific). Notes Techniques, Sciences de la Mer, Oceanographie Physique, No. 12, ORSTOM, Centre de Noumea, 43 pp.

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