Relationship between Periodic Meridional Fluctuations and Summertime Wave Patterns associated with Tropical-cyclone Tracks over the Western North Pacific

The meridional pattern exhibits a quasiperiodic fluctuating feature with a periodicity of 5–16 days in the East Asian summer monsoon region. In the high phase, the submonthly wave pattern propagates northwestward from the western North Pacific tropics to northern Luzon and is then forced to move westward due to a stationary, anomalous high-pressure system over southern Japan. The tropical cyclones (TCs) following an anomalous low-pressure system undergo a straight-moving propagation route through the northern South China Sea. However, in the low phase, the wave pattern and TCs tend to follow a recurving propagation route toward higher latitudes. Therefore, wave patterns under the influence of the quasiperiodic fluctuating meridional pattern affect the propagation routes of the wave patterns as well as the TC propagation directions.