Interdecadal changes in synoptic transient eddy activity over the Northeast Pacific and their role in tropospheric Arctic amplification

Abstract Arctic amplification refers to the greater surface warming of than other regions during recent decades. A similar phenomenon occurs in troposphere and is termed “tropospheric amplification” (TAA). The poleward eddy heat flux moisture are critical warming. In this study, we investigate synoptic transient activity over North Pacific associated with TAA its relationship subtropical jet stream, propose following mechanism. shift axis results anomalies meridional gradient zonal wind Pacific, which drive a dipole pattern wave intensity referred as Synoptic Transient Dipole (NPSTD). NPSTD index underwent an interdecadal late 1990s accompanying that stream. During positive phase index, transports more Circle, diverges, increasing temperature. This mechanism highlights need consider link between mean state upper TAA.