The Influence of Localization of Positive SST Anomalies in the Equatorial Pacific Ocean on Tropospherestratospheric Dynamics in Idealized Modeling

The paper shows the features of the dynamics of the Arctic stratospheric polar vortex (SPV) in winter under various large-scale ocean surface temperature (SST) anomalies in the equatorial zone of the Pacific Ocean. Based on the analysis of idealized modeling data, it was shown that positive SST anomalies in the Niño 3 (canonical El Niño) and Niño 4 (El Niño Modoki) regions lead to SPV weakening of varying degrees. In the experiments, SST anomalies were increased relative to observational data. With equal amplitude of SST anomalies in experiments with boundary conditions corresponding to canonical El Niño (CEN) and El Niño Modoki (ENM), in ENM experiment the vortex is on average 50 % weaker relative to the control experiment for the winter period (November–March), and in CEN experiment, – by 40 %. Analysis of the vertical component of the wave activity showed that in the ENM experiment there is a more intense propagation of Rossby waves from the troposphere to the stratosphere, the main differences are observed in the quasi-stationary planetary wave 2. Moreover, in contrast to some modern studies, it was found that the response of the pressure field in the mid-troposphere to El Niño Modoki is similar to the response to canonical El Niño and is expressed in an intensification of the Pacific-North American Oscillation. The only difference is that in the ENM experiment the negative geopotential anomalies are shifted to the south relative to the Aleutian low, and the maximum positive anomalies are located to the west of the area where they are located in the CEN experiment.