GPS PWV and Its Response to ENSO Activities in the Western Pacific Region During 2009–2011

This paper investigates the influence of El Niño Southern Oscillation (ENSO) activity through precipitable water vapor (PWV) variability to understand ENSO dynamics. PWV data over the western Pacific Ocean taken from Global Positioning System (GPS) and Radiosonde has been analyzed. An ENSO event represented by a sea surface temperature anomaly (SSTa) in the Niño 3.4 and 4 regions for the period of 2009–2011 was chosen. During this period, the PWV time series during increasing El Niño intensity were dominated by the seasonal cycle and a strong correlation found with SSTa for PIMO (R² = 0.81) and a modest correlation for TOW2 (R² = 0.66). An anticorrelation between SSTa and PWV was found at PIMO and TOW2 stations due to the fact that they are in opposite hemispheres, and a positive correlation was shown for the station near the equatorial line. This suggests that the strengthening and weakening of the trade winds moving from the central to the western Pacific Ocean during a La Niña event will bring to the surface warm water from the central to the western Pacific and cause PWV increases, and vice versa for an El Niño event.