A Strengthened Teleconnection of the Quasi-Biennial Oscillation and Tropical Easterly Jet in the Past Decades in E3SMv1

The Energy Exascale Earth System Model version 1 (E3SMv1) is a new global model that can generate a weakened tropical easterly jet (TEJ) during the easterly quasi-biennial oscillation (EQBO) and a strengthened TEJ during the westerly QBO (WQBO), which is referred to as the QBO-TEJ teleconnection. Although the longitudinal structure of the QBO-TEJ teleconnection is different between reanalysis and simulations, we hypothesize that simulations can still provide insights into the observed long-term changes in the QBO-TEJ teleconnection. The Atmospheric Model Intercomparison Project historical simulations (AMIP-historical) generate a strengthened trend in the correlation between the QBO and TEJ indices in the period of 1950-2014 as in reanalysis. The comparison of the AMIP-historical and the Coupled Model Intercomparison Project coupled historical simulations (coupled-historical) shows that the warming of the Indian Ocean has played a vital role in the strengthened QBO-TEJ teleconnection over the past six decades.

Automated summary

The Energy Exascale Earth System Model version 1 (E3SMv1) is able to generate a weakened tropical easterly jet (TEJ) during the easterly quasi-biennial oscillation (EQBO) and a strengthened TEJ during the westerly QBO (WQBO), known as the QBO-TEJ teleconnection. Despite the differences in the longitudinal structure of the QBO-TEJ teleconnection between reanalysis and simulations, it is hypothesized that simulations can still provide insights into the observed long-term changes in this teleconnection. The AMIP-historical simulations show a strengthened trend in the correlation between the QBO and TEJ indices from 1950 to 2014, similar to reanalysis. Comparison between AMIP-historical and coupled-historical simulations reveals the significant role of Indian Ocean warming in the strengthened QBO-TEJ teleconnection over the past six decades.