Intraseasonal oscillations of the Silk Road pattern lead to predictability in East Asian precipitation patterns and the Mei Yu front

Abstract The Silk Road pattern (SRP) is analysed on intraseasonal timescales over summer using empirical orthogonal functions (EOFs) of the meridional wind at 200 hPa. first two principal components explain almost equal amounts variance, hence both are required to represent SRP. associated spatial loadings 90° out phase with each other, providing evidence that propagating oscillations a natural mode variability This supported by Hovmöller diagrams hPa and EOFs, which show predominantly eastward-propagating oscillation. identified as plausibly being Rossby waves means waveguide theory. subtropical westerly jet East Asian rainfall patterns found be dependent oscillation: wet anomalies occur east troughs in jet, also regions where local entrances cause upper-level divergence via an ageostrophic circulation. Dry west troughs, convergence. time-delayed location Mei Yu front relative its climatology when there trough located Korean Peninsula, likely further north than normal 3–8 days later, before returning climatological position. suggests SRP acts potential source predictability front, might allow for better prediction rains.