How do Tropical SSTs Impact Moisture Transport into the Arctic?

Planetary-scale waves dominate Arctic moisture transport and its associated surface warming impacts in reanalysis data. Here we use an idealised aquaplanet model to clarify how tropical Sea-Surface Temperatures (SSTs) impact Arctic moisture transport by planetary waves. The results show that planetary waves dominate Arctic moisture transport and its associated surface warming in a control simulation driven by zonally-symmetric boundary conditions. Perturbing the zonal-mean or zonal-gradient of tropical SSTs in the control simulation impacts Arctic moisture transport primarily via changes in lower-tropospheric water vapour and transient eddies. Cooling tropical SSTs can impact Arctic moisture transport more than warming due to non-linearities in the SST response. The results highlight the role of statistically zonally symmetric processes in driving changes in Arctic moisture transport in addition to planetary waves generated by tropical warm pool SSTs hypothesized in previous work.