GPS meteorology: An investigation of ocean-based precipitable water estimates

A study of ship-based precipitable water (PW) estimation using the global positioning system (GPS) is presented for a field experiment in the coastal waters of Hawai'i. GPS precipitable water estimates, with a temporal resolution of 30 min, are shown to agree with radiosonde observations with an RMS error of 2.16 mm. The GPS PW time series is shown to possess significant value in identifying atmospheric features at both synoptic and mesoscale resolution throughout the experiment. Examples include influences from an upper level low-pressure system, shear lines, island blocking, and zones of low level convergence. Given PW's high spatial and temporal variability and the fact that it is not dynamically tied to other variables such as pressure or temperature, future PW estimates from ships could provide an important constraint for numerical weather prediction (NWP) models over ocean regions.