The contribution of eddies to striations in absolute dynamic topography

Distinct 4 year averages of absolute dynamic topography reveal striations in all ocean basins during 1993–2008. Striations are alternating mesoscale jet‐like structures observed in time‐averaged zonal geostrophic velocity, . They are characterized by speeds O (1 cm s –1 ) and are nominally separated by 200 km in the meridional direction. Similar patterns have been observed in sea level anomaly, mean dynamic topography, and Argo float measurements. Use of a tracked‐eddy database in concert with a contour identification and eddy removal algorithm demonstrates that eddies are a dominant source of striations in in the South Pacific (20°S–50°S, 200°E–280°E). Eddies with lifetimes ≥ 4 weeks account for 46–57% of the variance in and correlation coefficients between total and eddy‐only are 0.90–0.93. Attention is given to the ability of the algorithm to correctly identify eddies and suggests that a more appropriate bound on the variance due to eddies is ∼ 30–70%. This permits the existence of latent zonal jets and/or β ‐plumes. Additional findings of the study include (1) a large number of eddies having a broad range of amplitudes and scales contribute most to the eddy‐induced patterns and (2) the standard deviation of does not decay inversely with averaging period as proposed by a model of random eddies.