The correlations…


This shows correlations of peak season snow depth at Spencers Creek (near Charlotte Pass, from Snowy Hydro Limited) with four well known short-term climate variation modes — three oceanic and one polar. 2012 is shown in bold.

The modes are:

Southern Oscillation Index (SOI) is the difference between Tahiti and Darwin surface atmospheric pressures expressed as monthly standard deviations x10.  It is an indicator of the El Niño Southern Oscillation (ENSO), an east-west quasicycle in equatorial Pacific Ocean surface temperature and wind patterns which correlates with precipitation across much of Australia, including with alpine snow.  A positive SOI is associated with more (and some say wetter) Australian snow.

Pacific Decadal Oscillation (PDO) is a long-cycle, mostly north-south variation in the western Pacific Ocean, closely related (but not equivalent) to yet another claimed mode called the Inter-decadal Pacific Oscillation (IPO).  Negative long-average PDO is weakly correlated with more snow.  (2012 was the second “best” 2-year PDO on record…)

Indian Ocean Dipole (IOD) is an ENSO-like variation in the smaller Indian Ocean, which correlates with precipitation across southern Australia, including with alpine snow.

Antarctic Oscillation (AAO; also called “Southern Annular Mode” or SAM) is a measure of how tightly the circumpolar winds (“polar vortex” in one usage) blow around the pole.  A loose pattern (negative AAO) leads to more polar storms reaching southern Australia, and more snow.