PROPOSED INDICES CHARACTERIZING STRATOSPHERIC CIRCULATION AND TEMPERATURE FIELDS

Abstract

Two indices are proposed that characterize and quantify the circulation and temperature fields at stratospheric constant-pressure levels. The circulation index is calculated at 60° N. latitude as a normalized difference of the squared amplitudes of wave numbers 2 and 1 of the height field. The temperature index is the mean temperature gradient hetween the North Pole and 60° N. Comparisons of values of these parameters during several stratospheric warming episodes are utilized to show the difference between small-scale and large-scale warming events. Comparisons of values at different levels lead to the possibility of studying tropospheric-stratospheric interactions during periods of stratospheric warming.