A unique stratospheric warming event in November 2000

Abstract

Stratospheric sudden warmings frequently influence temperatures and circulation in the Arctic winter stratosphere. A unique stratospheric warming in Nov 2000 was characterized by wave 1 amplification with little phase tilt with height, a large displacement of the vortex off the pole, a warm pool at high latitudes, and a modest polar temperature increase, all of which are characteristic of early winter “Canadian” warmings. Unlike most Canadian warmings, the Nov 2000 event led to a strong zonal mean wind reversal for ∼9 days in the mid and lower stratosphere. Wind reversals during Canadian warmings occurred only three times before in the last 23 years. Midstratospheric minimum temperatures continued to decrease during the warming, but lower stratospheric temperatures increased substantially. The Nov 2000 warming was unique in its timing, intensity and duration, and in its impact on the development of the polar vortex, especially in the lower stratosphere.