Index Value Plot: PDO Index

Source: http://wattsupwiththat.com/2009/08/17/evidence-that-ocean-net-heat-flow-is-connected-with-climate-shifts-co2-not-correlated/

Index value plots are very similar to line graphs except they can compare more than one variable of data and the index value is the variable that is plotted on the graph instead of the absolute value of the information. In the map above the monthly value of the PDO value in the Pacific Ocean is being depicted from 1900-2013.