Looper trajectory segments in Global Drifter Program data

Looper trajectory segments

Version number: 0.1. Most recent data included: 30 December 2014. Created on: 2 November 2015. Documentation: Lumpkin (2015), manuscript submitted to J. Geophys. Res.

On this page, you'll find looper trajectory segments identified from Global Drifter Program data, using the methodology documente in Lumpkin (J. Geophys. Res., submitted). NOTE: results are subject to change, pending potential necessary revisions.

Three versions of these data are available. The first version ( is a self-explanatory NetCDF file which contains the same variables as the Matlab file described below. The second version is an ASCII metadata file with drifter IDs, dates and times when looping started and ended, the median period and radius of looping, and whether the looping was cyclonic (+1) or anticyclonic (-1). The third version (loopers.mat) is a Matlab file with 6-h values of the following variables:

T_L: integral time scale from velocity correlation function (days).
drogue: drogue presence (1=drogued, 0=undrogued, .5=uncertain).
id: unique identification number.
lat: latitude (degrees; negative = south).
lon: longitude (degrees; negative = west).
omega: spin omega (s^-1)
period: period of rotation (days; =2 pi / omega).
perFit: period from velocity correlation function (days).
persist: persistence of looping (days).
radius: orbital radius (m).
t: time (days since 1/1/1979).
u: zonal velocity (m/s).
v: meridional velocity (m/s).