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)
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.