AOML receives position data computed from Doppler measurements from Argos-tracked drifters or from GPS installed in all Iridium and some Argos drifters. Historically, these data are irregularly distributed in time and they also contain erroneous positions and/or bad Sea Surface Temperature values, therefore not suited for many kinds of analysis or displays. The Drifter Data Assembly Center (DAC) at AOML applies quality control procedures to edit these data (position and temperature) and interpolates them to 6-hour intervals using an optimum interpolation procedure called kriging, which is commonly used for two and three-dimensional analyses. Some drifters have other sensors attached such as barometric pressure, salinity, wind speed and direction, but these data are stored in their raw form and kept in the archives, with no further editing done at the present time. See Hansen, D.V. and Poulain, P.M., 1996, [PDF] for a complete description of the quality controlled and interpolation procedures applied to the drifter data in this database.
To FTP all data files (ASCII text ASCII compressed format):
Login as an 'anonymous' user to ftp.aoml.noaa.gov and proceed as follows:
At the system (e.g. unix) prompt, enter commands shown below:
unix> ftp ftp.aoml.noaa.gov
ftp> cd phod/pub/buoydata
ftp> prompt off
ftp> mget *
Or go directly to:
ftp://ftp.aoml.noaa.gov/pub/phod/buoydata/ and download all desired files.
Drifter data is broken into four smaller files for easy download.
These data files are accompanied by Metadata Files (sometimes referred to as the "directory file") containing the initial transmission time and position, drogue off date, final time and position, death code, etc. for each drifter. The directory file for each dataset can be found below: