Shipboard Acoustic Doppler Current Profiling

on RVIB Nathaniel B. Palmer and RVIB Laurence M. Gould

The US National Science Foundation (NSF) Office of Polar Programs (OPP) funds the operation of two Research Vessel Ice Breakers (RVIB) in the Antarctic: the Nathaniel B. Palmer and the Laurence M. Gould. Both ships now have two shipboard ADCPs, an RD Instruments narrowband VM-150 profiler, and an Ocean Surveyor (phased array) 38 KHz profiler. The ADCP system is made up of these two instruments along with with precision (PPS, or P/Y-code) GPS navigation and with heading corrections provided by Seapath or Ashtech ADU-2 GPS attitude sensors. These systems offer the prospect of routine high-resolution current profile measurements in the top 300 m and lower resolution profiling as deep as 1200m, along a variety of cruise tracks through otherwise rarely sampled waters of the Southern Ocean.

Dr. Teresa Chereskin at Scripps Institution of Oceanography and Eric Firing at University of Hawaii are funded by the NSF OPP to oversee the operation of these ADCP systems.

At sea, data from two ADCPs are collected by a single Linux computer. Data streams logged by the Linux machine include roughly one-second gyro heading, Ashtech (or Seapath) heading, gps position, speed of sound, and single-ping adcp data from each instrument. The Linux computer averages the single-ping data into 5-minute averages and processes these averaged data creating a regularly updated, preprocessed and edited dataset. Once a day, it emails us a report with system information, data quality parameters, and a sample of recent data. Figures are generated at University of Hawaii upon reciept of the email. Throughout the day, the on-board Linux system updates figures on a ship's website. (This example is from the Gould, heading north over the Patagonia shelf). The onboard website is accessible to anyone on the ship's network, and contains links to recently generated figures, the data used to create them, and adcp logging system documentation. Access to the data is also provided through shared disks for Microsoft or Linux machines on the ship's network.

As part of this project, summary plots for N.B.Palmer cruises will be available on this web site. Go here to see the cruises which are ready.

The data collected on the L.M.Gould undergoes a similar treatment; daily plots are posted here.

Processed data are archived by the NODC JASADCP. The present list of online NB Palmer data sets is here.

Status of the project and more plots of the resulting measurements will be added to this page.

These data were processed at the University of Hawaii with support from NSF (OCE9816483).