Ocean climate variaibility

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Interannul time scale- e.g. El Nino souther oscillation 2-7years

Decadal time scales- Ocean Basin wide variability-e.g. Pacific decadal oscillation; North Atlantic oscillation. 

Pacific Decadal Oscillation:

Long term climate shifts affect populations of the species within the ecosystem e.g. Seabirds and Sardines in the pacific ocean.

Off the coast of California- sardines supported a fishery Montery bay, California- can see that ocean temperatures are strongly correlated with abundance of sardine eggs- concentrated in the cooler waters- upwellings. (Checkley et al, 2000). 

Regional indices reflect large-scale climatic variations. In the pacific- Pacific Decadal Oscillation- principle component- one value ( a type of multi-varient analysis- a way of summarising many variables). 

Negative/ Anomaly NDP:- less pronounced low pressure in the N. Pacific compared the the average

Positive/ Anomaly PDO: -more pronounced low presure in the N. Pacific compared to the average

This affects the sea surface temperatures:

  • Negative-warmer than usual in the central N. Pacific but cooler alon American coast
  • Positive-cooler than usual in the central N. Pacific but warmer along the American coast

Sardines in +ve phase: Higher primary production + salmon in the far North but much lower off coast of California- weak californian curret- low nutrients etc.

Sardines in -ve phase: Higher primary productivity + Salmon off coast of Caifornia- stronger upwelling but less in the far North. (Chavez et al, 2003)

Atlantic:

Icelandic low + Azores High

Seesaw/shifting pattern of atmospheric mass- alternates between the polar and subtropical regions

Changes in the mass and pressure fields=variability in strenth and pathway of storm systems crossing the Atlantic from the US East coast to Europe.

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