On the factors influencing the development of sporadic upwelling in the Leeuwin Current system

Vincent Rossi*, Ming Feng, Charitha Pattiaratchi, Moninya Roughan, Anya M. Waite

*Corresponding author for this work

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

While there is no persistent upwelling along the West-Australian (WA) coastline, sporadic upwelling events have been documented primarily in summer. By analyzing comparatively the variability of both Ekman and geostrophic cross-shore transports over a seasonal cycle, we show that the situation is more contrasted. Based on a composite index computed from satellite data over a 15 year period, calibrated with well documented events, we investigate the factors influencing the development of sporadic upwelling in the region. Overall, the occurrence of transient upwelling events lasting 3-10 days varies largely in space and time. Shelf regions at 31.5 and 34°S are favored with up to 12 upwelling days per month during the austral spring/summer. Although being generally favored from September to April, sporadic upwelling events can also occur at any time of the year at certain locations north of 30°S. On average over 1995-2010, the Ningaloo region (22.5°S) cumulates the highest number of upwelling (∼140 days per year) and is characterized by longer events. The intensity of intermittent upwelling is influenced by the upwelling-favorable winds, the characteristics of the Leeuwin Current (e.g., onshore geostrophic flow, mesoscale eddies and meanders, stratification and nitracline) and the local topography. This suggests that short-living nutrient enrichment of variable magnitude may occur at any time of the year at many locations along the WA coast.

Original languageEnglish
Pages (from-to)3608-3621
Number of pages14
JournalJournal of Geophysical Research: Oceans
Volume118
Issue number7
DOIs
Publication statusPublished - 2013
Externally publishedYes

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