Title: Transport by Lagrangian Vortices in the Eastern Pacific,
Abstract: Rotationally coherent Lagrangian vortices (RCLVs) are identified from
satellite-derived surface geostrophic velocities in the Eastern Pacific
(180$^\circ$-130$^\circ$ W) using the objective (frame-invariant) finite-time
Lagrangian-coherent-structure detection method of Haller et al. (2016) based on
the Lagrangian-averaged vorticity deviation. RCLVs are identified for 30, 90,
and 270 day intervals over the entire satellite dataset, beginning in 1993. In
contrast to structures identified using Eulerian eddy-tracking methods, the
RCLVs maintain material coherence over the specified time intervals, making
them suitable for material transport estimates. Statistics of RCLVs are
compared to statistics of eddies identified from sea-surface height (SSH) by
Chelton et al. 2011. RCLVs and SSH eddies are found to propagate westward at
similar speeds at each latitude, consistent with the Rossby wave dispersion
relation. However, RCLVs are uniformly smaller and shorter-lived than SSH
eddies. A coherent eddy diffusivity is derived to quantify the contribution of
RCLVs to meridional transport; it is found that RCLVs contribute less than 1%
to net meridional dispersion and diffusion in this sector, implying that eddy
transport of tracers is mostly due to incoherent motions, such as swirling and
filamentation outside of the eddy cores, rather than coherent meridional
translation of eddies themselves. These findings call into question prior
estimates of coherent eddy transport based on Eulerian eddy identification
methods.