GPS water vapor monitoring and TroWav updated for ENSO studies

The GPS receiver and the meteorology sensors have been installed at Universiti Malaysia Sabah (UMS), Kota Kinabalu (UMSK: 6.03°N, 116.12°E and 63.49 m) for study a climate condition that has associated with El Niño Southern Oscillation (ENSO). The atmospheric precipitable water vapor (PWV) derived from GPS technique was used as an indicator of ENSO detection. In the processing, the Niell Mapping Function (NMF) used to map the atmospheric delay from zenith to the line-of-site was updated using the Vienna Mapping Function (VMF). With GPS antenna co-located with meteorological sensors, the comparison of GPS PWV with time-dependent surface pressure and sea surface temperature (SST) during the first ten weeks observation found that surface pressure is opposed to the PWV changes.