The large-scale motions in the atmosphere show a convection cell (convective loop). the bold dark arrows show that air is rising in the stormy weather area of the western pacific and [(rising)(sinking)] in the eastern tropical pacific.

Sinking

Explanation:

The weather conditions of the water and in the air during El Nino changes, while the air pressure is higher in the central pacific during normal conditions, it changes during El nino and is lower in the center of the pacific than to the west.

Due to these changes, trade winds get weaker and the flow of the water goes in the opposite direction, thereby sinking in the east.