Westgarth-Smith, Leroy, and Collins established that it is highly correlate
Westgarth-Smith, Leroy, and Collins established that it is highly correlated with populations of P. aegeria, P. icarus, and other butterfly species in Britain. It has an analogue in the southern hemisphere, the Southern Annular Mode, which similarly acts as a source of stochastic noise in the climate system reddened by interactions with the ocean. It has been found that one to two years after it reaches a peak, the Gulf Stream is displaced northward. In its negative phase, moisture moves more toward the Mediterranean basin and leaves the UK drier and cooler, while its positive phase means a warm and wet winter and autumn in the UK. For 10 points, what is this phenomenon measured as a difference in air pressure between Iceland and the Azores, Lisbon, or Gibraltar, and named for its geographic location?
Westgarth-Smith, Leroy, and Collins established that it is highly correlated with populations of P. aegeria, P. icarus, and other butterfly species in Britain.
North Atlantic Oscillation (or NAO index)