Areas where the —— are significant at/above the 95% level are stippled.
The tropospheric waves that can propagate into the stratosphere are the predominant wavenumber-1 and wavenumber-2 waves
Charney, J. G. & Drazin, P. G. Propagation of planetary-scale disturbancesfrom the lower into the upper atmosphere.J. Geophys. Res.66,83–109 (1961).
the strengthening of the SAV is indeed closely related to the weakening of the upward propagation of the wavenumber-1 planetary wave.
The polar cap height (PCH) anomaly is a good indicatorof the variability of the polar vortex. Here, the sign-reversed geopotential height (NPCH) anomalies averaged over 65°N–90°N at 50 hPa are used to describe the strength of the SAV, i.e., apositive (negative) NPCH anomaly corresponds to a strengthened(weakened) SAV.
Baldwin, M. P. & Thompson, D. W. J. A critical comparison of stratosphere-troposphere coupling indices.Quart. J. Roy. Meteor. Soc.135, 1661–1672 (2009).
The gridded data of the vertical component (EPz) of EP flux were weighted by the square root of the cosine of latitude to ensure that equal areas were afforded equal weight in the analyses.
We regressed the wintertime unweighted anomaly fields upon the standardized principal component (PC) time series and plotted the resulting regression coefficients. Thus, the val-ues in the regression maps corresponded to anomaly values that were associated with one standard deviation anomaly in the PC time series. The linear correlation coefficients were calculated between time series. A two-tailed Student’s t-test was employed to test the significance of the results.
Wei, K., Ma, J., Chen, W., Vargin, P., 2021. Longitudinal peculiarities of planetary waves-zonal flow interactions and their role in stratosphere-troposphere dynamical coupling. Climate Dynamics 57, 2843–2862.. doi:10.1007/s00382-021-05842-5