Advanced Weather Prediction and Severe Weather Monitoring Using National GNSS CORS Infrastructure - Preliminary Results

Atmospheric water vapour (AWV) plays an important role in the pursuit of weather research, in particular extreme weather phenomena. Conventional atmospheric sounding methods including radiosonde and water vapour radiometer (WVR)) have the disadvantages of low spatial or temporal resolutions or high cost. As an emerging remote sensing approach of AWV, GPS is an ideal complement due to its unique advantages of 24-hour availability, high accuracy and low cost. As a critical part of the Australian positioning infrastructure, several regional Continuously Operating Reference Stations (CORS) networks have been established in the past two decades. The huge amount of GPS measurements provided by these CORS infrastructures are a rich data source that can be used for many applications in addition to positioning. This research aims to use GPS observations from Australian CORS networks to derive values of local atmospheric variables for weather prediction and severe weather monitoring. Our initial research task was to investigate approaches to obtain the GPS-derived tropospheric zenith total delay (ZTD) which is directly related to AWV. Preliminary results from both Precise Point Positioning (PPP) and Double Difference (DD) approaches available in Bernese software are presented in this paper. GPS data for the periods of the three heavy storm events occurred in Victoria (2012), Queensland (2011) and Victoria (2010) were selected for testing. The results showed that the GPS-derived ZTD from both PPP and DD agreed with the ZTD derived or provided from other data sources, including IGS tropospheric products from Center for Orbit Determination in Europe (CODE), and synoptic and radiosonde data from the Australian Bureau of Meteorology, at the level of several millimetres. This implies that the use of GPS observations from the well-distributed national CORS infrastructure over Australia to complement the current atmospheric sounding systems is promising. It has great potential to use these GPS observations to obtain atmospheric variable values with high spatial-temporal resolution, thanks to the all-day GPS observability and the dense distribution of the CORS networks. The synthetic integration of the GPS-derived atmospheric results with meteorological data from other spaceand ground-based atmospheric sensors has significance for severe weather monitoring and prediction for the Australian region.