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Humboldt Current System

Humboldt Current System. Holly Gonzales December 4, 2013. Characteristics. Eastern boundary of subtropical South Pacific Gyre B ordering Chile and Peru Cold water current Mean surface speed: 6 cm/s Shallow: ~100 m Driven by alongshore equatorward winds

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Humboldt Current System

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  1. Humboldt Current System Holly Gonzales December 4, 2013

  2. Characteristics Eastern boundary of subtropical South Pacific Gyre Bordering Chile and Peru Cold water current Mean surface speed: 6 cm/s Shallow: ~100 m Driven by alongshore equatorward winds Ekman offshore transport creates upwelling zone High primary productivity

  3. Current System • ACC = Antarctic Circumpolar Current • splits north and south • HC = Humboldt Current • Subantarctic Water (SAAW) • Chile Coastal Current • CHC = Cape Horn Current • PC = Peru Countercurrent • Warmer, saltier transported south (Subtropical Water) • PCU = Peru-Chile Undercurrent • 150-300m depth • subsurface salinity maximum (Equatorial Subsurface Water) N. Silva et al., 2009

  4. T-S Plot of Region N. Silva Et al., 2009 Subtropical Water (STW) – Salty and warm Subantarctic Water (SAAW) – Fresher and cold Equatorial Subsurface Water (ESSW) – Salinity maximum and cold Antarctic Intermediate Water (AAIW) – Fresher and very cold Pacific Deep Water (PDW) – very cold and saltier

  5. Water Masses Water mass percentages (A) Longitudinal Section (B) Latitudinal Section at 28° S (C) Latitudinal Section at 43° S STW=Subtropical Water, SAAW=Subantarctic Water, ESSW=Equatorial Subsurface Water, AAIW=Antarctic Intermediate Water, PDW=Pacific Deep Water N. Silva Et al., 2009

  6. Seasonal Variability – Chile Coastal Current Spring and summer - coastal jet structure Fall – Jet moves farther from shore Winter – Weak equatorward flow Winter, South of 36° S -poleward flow, downwelling AGUIRRE ET AL.: SEASONAL DYNAMICS OF THE ALONGSHORE FLOW

  7. El Niño Water temperatures increase by 2 to 3° C Sea level rises 40 to 50 cm Weakened upwelling Reduced nutrient availability Anchovy and other fish populations collapse

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