Aspects of interannual and intraseasonal variability of the tropopause and lower stratosphere

Abstract

AbstractRadiosonde and National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data are utilized to consider aspects of large‐scale variability in tropopause height, temperature and pressure. This variability is related to coherent dynamical fluctuations in the troposphere and lower stratosphere through the use of linear correlation and regression. On interannual time‐scales, significant global‐scale tropopause fluctuations are tied to variability in sea surface temperature (SST) associated with the El Niňo/Southern Oscillation phenomenon. When SST is anomalously high in the central tropical Pacific, tropopause height (pressure) is high (low) throughout the Tropics, with largest perturbation amplitudes in the subtropical Pacific. At the same time, the tropopause is cold over the tropical and subtropical Pacific sector but warm elsewhere in the Tropics. Over the extratropics, wave‐like perturbations in the tropopause are seen, with anomalous cyclonic flow corresponding to a lower tropopause height and higher tropopause temperature and pressure, and vice versa. The sign of the temperature anomalies in the lower stratosphere tends to match that at the tropopause over much of the globe, with opposite‐signed anomalies in the upper troposphere. The vertical structure of these perturbations is consistent with the expected potential‐vorticity anomalies induced by quasi‐stationary Rossby waves and vertically propagating gravity waves forced by displacements of tropical convection. Similar relationships are associated with the eastward propprotion of tropical convection due to the Madden‐Julian Oscillation on intraseasonal time‐scales.