Orographic mechanical and surface thermal effects of the Tibetan–Iranian Plateau on extratropical intraseasonal waves in boreal summer: numerical experiments

Abstract The intensity and location of boreal summer extratropical intraseasonal oscillations along the subtropical westerly jet (EISO-SJ) are crucial in triggering distributing extreme events over Eurasia. Based on numerical experiments, this study distinguishes orographic mechanical surface thermal forcing Tibetan–Iranian Plateau (i.e. TIP-MF TIP-TF) EISO-SJ. primarily modulates amplitude EISO-SJ that strengthens upstream weakens downstream. Comparatively, TIP-TF not only reduces/increases TIP upstream/downstream, but also significantly migrates track northward. Further analysis demonstrates changes jet, eddy energy propagation conversion consistent with This indicates variations sensible heating interannual variation global change, as well terrain uplift paleoclimate influence mid-latitude subseasonal variation.