This page contains instructions to download global hourly location and velocities from GDP surface drifters tracked by Argos or GPS, as described in Elipot et al. (2016), "A global surface drifter dataset at hourly resolution", J. Geophys. Res. Oceans,121 doi:10.1002/2016JC011716. These data are a subset of the historical 6h data when hourly resolution became possible.
Version 1.04, released October 2020
Release notes for version 1.04:
The data are provided as Matlab files and as NetCDF files.
The data from Argos-tracked drifters are in the files containing the acronym WMLE (Weighted Maximum Likelihood Estimation), referring to the interpolation method used for Argos fixes. The data from GPS-tracked drifters are in the files containing the acronym GPS. Please refer to the accompanying README file, using a secure FTP client, such as FileZilla.
For the NetCDF files please refer to the metadata within these files.
To download the Matlab files, click the links below:
To download the NetCDF files,
using a secure FTP client, such as FileZilla, go directly to :
ftp://ftp.aoml.noaa.gov/pub/phod/lumpkin/hourly/v1.04/netcdf/ and download the files you need.
Queries, questions, comments, and the reporting of issues with these products should be directed to Drs. Rick Lumpkin or Shane Elipot. If you would like to receive notifications of updates to the hourly data set, email your request to Rick Lumpkin.
If you use this dataset in your studies and publications, please cite:
Elipot, S., R. Lumpkin, R. C. Perez, J. M. Lilly, J. J. Early, and A. M. Sykulski (2016), "A global surface drifter dataset at hourly resolution", J. Geophys. Res. Oceans, 121, doi:10.1002/2016JC011716.
Preliminary analyses of the drifter velocity variance showed that this dataset is a valuable new tool for the study of relatively small-scale and high-frequency, oceanic processes. In particular, velocity rotary spectra suggest that high frequency tidal and internal wave motions are detectable globally. Below is a figure adapted from Elipot et al. (2016) which illustrate that the new dataset exhibits more velocity variance compared to the 6-hourly velocity product.
Figure caption: (a) zonally averaged drifter rotary velocity spectra in 1 degree latitude bins from 2048-hour (~85 days) trajectory segments at 1-hour resolution, overlapping by 50 percent, from the new global hourly product. (b) same as in (a) but zoomed in for frequencies in the range +/- 3.2 cpd. The black dashed curve indicates the inertial frequency (-f/(2*pi) cpd) and the white dashed curve the Coriolis frequency (f/(2*pi) cpd). Note that the color scales indicate different ranges of values and are both saturated. (c) same as in (b) but calculated from the post-2005 6-hourly Kriged global product for the same trajectories.