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Strengthened causal connections between the MJO and the North Atlantic with climate warming
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  • Savini M. Samarasinghe,
  • Elizabeth A. Barnes,
  • Charlotte Connolly,
  • Imme Ebert-Uphoff,
  • Lantao Sun
Savini M. Samarasinghe
Colorado School of Mines, Colorado School of Mines

Corresponding Author:[email protected]

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Elizabeth A. Barnes
Colorado State University, Colorado State University
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Charlotte Connolly
Colorado State University, Colorado State University
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Imme Ebert-Uphoff
Colorado State University, Colorado State University
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Lantao Sun
Colorado State University, Colorado State University
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Abstract

While the Madden Julian Oscillation (MJO) is known to influence the midlatitude circulation and its predictability on subseasonal-to-seasonal (S2S) timescales, little is known how this connection may change with anthropogenic warming. This study investigates changes in the causal pathways between the MJO and the North Atlantic Oscillation (NAO) within historical and SSP585 simulations of the CESM2-WACCM coupled climate model. Two data-driven approaches are employed, namely, the STRIPES index and graphical causal models. These approaches collectively indicate that the MJO’s influence on the North Atlantic strengthens in the future, consistent with an extended jet-stream. In addition, the graphical causal models allow us to distinguish the causal pathways associated with the teleconnections. While both a stratospheric and tropospheric pathway connect the MJO to the North Atlantic in CESM2-WACCM, the strengthening of the MJO-NAO causal connection over the 21st century is shown to be due exclusively to teleconnections via the tropospheric pathway.
16 Mar 2021Published in Geophysical Research Letters volume 48 issue 5. 10.1029/2020GL091168