Observations of Precipitable Water Vapor along the Maritime Continent Associated with El Niño-Southern Oscillation Activity

The effect of El Niño and La Niña events is a major issue in the regional climate of Southeast Asia. This study uses the Precipitable Wa- ter Vapor (PWV) values estimated from Global Navigation Satellite System (GNSS; in particular Global Positioning System, GPS) to in- vestigate the El Niño-Southern Oscillation (ENSO) activity in the Southern coast of the South China Sea (SCS). For this study, GPS and meteorological systems are installed at the Universiti Malaysia Sabah, Kota Kinabalu (UMSK), which is located on the coast of the mar- itime continent. Subsequently, PWV from GPS and PWV obtained from Radiosonde, prior to the investigation of ENSO activity, are com- pared. To further investigate the relationship between PWV and ENSO activities, data from three additional GPS stations located along the coast of SCS during the 3-year period 2009-2011 were analyzed. The selection period considers the availability of GPS data. The obtained results show that during the increased intensity of El Niño in 2009/2010, PWV decreases and drops about 10-week later, i.e., after the sea surface temperature anomaly (SSTa) has peaked. PWV has a negative correlation with the El Niño index, which is comparable with pre- cipitation data obtained from NASA’s Tropical Rainfall Measuring Mission (TRMM). In contrast, the amount of PWV was increased dur- ing the La Niña event of 2010/2011. This observation suggests the GPS is a suitable technique for studying the ENSO activity.