Simulations of development of tropical disturbances associated with the monsoon trough over the western North Pacific

The genesis of tropical disturbances in strong and weak monsoon trough (MT) patterns is examined in an idealized model. The initial MT patterns in the model simulations are obtained from a global reanalysis dataset that encompasses a 29‐year period. The simulations show that a tropical disturbance tends to develop over the eastern part of western North Pacific (WNP) near 150°–160°E when the MT extends eastward, whereas a tropical disturbance tends to occur over the western part of the WNP near 120°–130°E when the MT retreats westward. In addition, there is a faster development of tropical disturbance with a greater intensity in the strong MT pattern than that in the weak MT pattern. The tropical disturbances are triggered in the most convectively unstable region through the local dynamic and thermodynamic processes in the strong and weak MT patterns.