Nathaniel B. Palmer 0209 - underway geophysical data

This data set contains underway geophysical data collected on a transit cruise between Lyttelton, New Zealand and McMurdo Base, Antarctic during December of 2002. We collected gravity data using a shipboard Lacoste-Romberg gravimeter, magnetic field data, a proton precession magnetometer towed behind the ship, swath bathymetry with a Simrad EM120 multibeam system, centerbeam depth (bathymetry beneath the ship), and single channel seismics. IGRF2000, calculated for the appropriate date and location, was subtracted from the observed magnetic field to yield the total field magnetic anomaly. The major scientific objectives of the cruise were: a) a small survey of the axis of the Pacific-Antarctic ridge along the southwesternmost extension of the ridge, providing constraints on the Euler pole, b) a survey of the magnetic anomalies in southern part of the Adare Basin, just north of the Northern Basin in the Ross Sea, showing the continuity of structures between the Adare Basin and Northern basin, c) single channel seismic reflection lines on the western side of the Adare Basin imaging the structures associated with the opening of this basin, d) and collection of ADCP, temperature and salinity data along the track. Related data sets that cannot currently be archived at the National Data Centers include ODEC Bathy2000 3.5 kHz echo sounder files with up to 100 m subbottom penetration, which are available in SEG-Y format from the chief scientist. There is no currently open national archive for these data. When one becomes available in the future we plan to archive the data there. The Simrad EM120 data will be sent to NGDC and have already been sent to the RIDGE bathymetric data base at Lamont-Doherty Earth Observatory. They are available in hourly files in raw and edited formats suitable for use with the MB-systemsoftware. The Simrad EM120 data and the ODEC Bathy2000 3.5 kHz data were collected continuously throughout the cruise.