PhOD - Global Drifter Program

Six-Hourly Interpolated Data

Please cite the following if you use these data: Lumpkin, Rick; Centurioni, Luca (2019). Global Drifter Program quality-controlled 6-hour interpolated data from ocean surface drifting buoys. [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/7ntx-z961. Accessed [date].

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. Hourly interpolated data is also available for a subset of the drifters.

Interpolated ERDDAP Database

Advanced queries, like getting data in a desired format (i.e., ASCII, NetCDF, Matlab, etc.), selecting specific drifters, isolating drifter data within a particular time period and/or region are made possible using the AOML GDP ERDDAP. For instructions how to navigate the ERDDAP server, establish machine to machine (m2m) requests, and customize your data request, variant_date_to_timestamp 6-Hour Interpolated Data Request Instructions. For additional resources and step-by-step guidance, visit the AOML GDP ERDDAP Tutorial on

To plot and view quality controlled interpolated data from a specific drifter or a batch of drifters spanning a particular time period and/or region, visit the 6-Hour Interpolated Data Graphing ERDDAP and follow the 6-Hour Interpolated Data Graphing Instructions, or visit the AOML GDP ERDDAP Tutorial on YouTube.

Additional Options for Downloading QC Drifter Data

To access all data files (ASCII text ASCII compressed format):

Please note: We now have 4 separate data and directory files, since we exceeded 20,000 records and the original file was getting too large. Some modifications were made to older files, so if you downloaded data prior to May 2016, reload all updated files.
A list of fields, their respecitive format, units, and a brief description can be found here.

Choose the desired file:

File buoydata_1_5000.dat.gz contains data from the earliest 5,000 drifters.
This file was last revised in May, 2016.

File buoydata_5001_10000.dat.gz contains drifters 5,001 through 10,000.
This file was last revised on May, 2016.

File buoydata_10001_15000.dat.gz contains drifters 10,001 through 15,000.
This file was last revised on May, 2016.

File buoydata_15001_current.dat.gz is updated quarterly.
Download the most recent version of this file.

Visit www.aoml.noaa.gov/ftp/phod/buoydata/ and select the desired file(s).

Or, using a secure FTP client, such as FileZilla, go directly to:

ftp://ftp.aoml.noaa.gov/pub/phod/buoydata/ and download the desired file(s).

Metadata

These data files are accompanied by Metadata Files (sometimes referred to as the "directory file"). For a list of fields, their respecitive format, units, and a brief description, visit Metadata Field Description. The directory file for each dataset can be found below.

buoydata_1_5000.dat.gz -- dirfl_1_5000.dat
buoydata_5001_10000.dat.gz -- dirfl_5001_10000.dat
buoydata_10001_15000.dat.gz -- dirfl_10001_15000.dat
buoydata_15001_MMMYY.dat.gz -- dirfl_15001_current.dat

Ragged Array files

The 6-hourly dataset is also available through FTP as single files containing contiguous ragged arrays, one for each data variable, as well as all metadata.

Two file formats are available, NetCDF and Apache Parquet.

NetCDF

Visit www.aoml.noaa.gov/ftp/pub/phod/buoydata/gdp6h_ragged_sep23.nc for the NetCDF file.

Or, using a secure FTP client, such as FileZilla, go directly to:

ftp://ftp.aoml.noaa.gov/pub/phod/buoydata/gdp6h_ragged_sep23.nc.

Apache Parquet

Visit www.aoml.noaa.gov/ftp/pub/phod/buoydata/gdp6h_ragged_sep23.parquet for the parquet file.

Or, using a secure FTP client, such as FileZilla, go directly to:

ftp://ftp.aoml.noaa.gov/pub/phod/buoydata/gdp6h_ragged_sep23.parquet.