The 1997--1998 El Ni¿o had a profound impact on atmospheric circulation in the tropical Pacific and affected weather patterns world-wide. Precipitable water estimates from Global Positioning System (GPS) sites in the western tropical Pacific capture the sudden onset of large-scale subsidence, a phenomenon proposed as a possible mechanism driving the eventual decline of El Ni¿o episodes. The atmospheric drying associated with this anomalous high-pressure ridge and the turnabout as the warm episode transitions into the subsequent La Ni¿a are clearly visible in the GPS observations. ¿ 2000 American Geophysical Union