Determining the 4D Dynamics of Wet Refractivity Using GPS Tomography in the Australian Region

The Earth’s climate and weather is a highly dynamic and complex system. Monitoring and predicting meteorological conditions with a high accuracy and reliability is, therefore, a challenging task. Water vapour (WV) has a strong influence on the Earth’s climate and weather due to the large energy transfers in the hydrological process. However, it remains poorly understood and inadequately measured both spatially and temporally, especially in Australia and the southern hemisphere. Four dimensional (4D) WV fields may be reconstructed using a tomographic inversion method that takes advantage of the high density of ground-based GPS Continue Operating Reference Station (CORS) networks. Recent development in GNSS tomography technique based on the dense Australian national positioning infrastructure has the potential to provide near real time 4D WV solutions at a high spatial and temporal resolution for numerical weather prediction, severe weather monitoring and precise positioning. This paper presents a preliminary study using the most advanced state CORS network—GPSnet as a test bed and introduces 4D GPS tomography in Australia and evaluates different parameters for voxel and height resolution and the influence of a priori data through simulations in a controlled field. Preliminary analyses of a real data campaign using a priori information are presented. These preliminary results conclude that the most optimal setup for GNSS tomography models in Victoria is: ∼55 km horizontal resolution and 15 vertical layers with a smaller spacing in the lower troposphere and a larger spacing towards the tropopause. Further analysis will be undertaken to optimize the parameter settings for real data processing. The initial investigation into real data analysis has concluded an overall RMS error of 5.8 ppm with respect to the operational Australian Numerical Weather Prediction (NWP) model for 1 day.

[1]  T. Herring,et al.  GPS Meteorology: Remote Sensing of Atmospheric Water Vapor Using the Global Positioning System , 1992 .

[2]  Christian Rocken,et al.  GPS/STORM—GPS Sensing of Atmospheric Water Vapor for Meteorology , 1995 .

[3]  A. Niell.  Global mapping functions for the atmosphere delay at radio wavelengths , 1996 .

[4]  Christian Rocken,et al.  Sensing integrated water vapor along GPS ray paths , 1997 .

[5]  Paul Tregoning,et al.  Accuracy of absolute precipitable water vapor estimates from GPS observations , 1998 .

[6]  Mohinder S. Grewal,et al.  Global Positioning Systems, Inertial Navigation, and Integration , 2000 .

[7]  G. Ruffini,et al.  4D tropospheric tomography using GPS slant wet delays , 2000 .

[8]  W. Bertiger,et al.  A technical description of atmospheric sounding by GPS occultation , 2002 .

[9]  Per Jarlemark,et al.  Ground-Based GPS Tomography of Water Vapor: Analysis of Simulated and Real Data , 2004 .

[10]  Zhengdong Bai,et al.  Near-Real-Time GPS Sensing of Atmospheric Water Vapour , 2005 .

[11]  T. Nilsson.  Assessment of Tomographic Methods for Estimation of Atmospheric Water Vapor Using Ground-Based GPS , 2005 .

[12]  Marie-Noëlle Bouin,et al.  GPS water vapour tomography: preliminary results from the ESCOMPTE field experiment , 2005 .

[13]  G. Lachapelle,et al.  Regional Tropospheric Tomography Based on Real-Time Double Difference Observables , 2005 .

[14]  Alain Geiger,et al.  Determination of the spatial and temporal variation of tropospheric water vapour using CGPS networks , 2006 .

[15]  Armin Raabe,et al.  Preconditions to ground based GPS water vapour tomography , 2007 .

[16]  L. Mervart,et al.  Bernese GPS Software Version 5.0 , 2007 .

[17]  Maorong Ge,et al.  Validation of GPS slant delays using water vapour radiometers and weather models , 2008 .

[18]  G. Ruffini,et al.  Tropospheric Tomography using GPS Estimated Slant Delays , 2008 .

[19]  S. Lutz,et al.  High-resolution GPS tomography in view of hydrological hazard assessment , 2008 .

[20]  Xiaohua Xu,et al.  Assessing COSMIC GPS radio occultation derived atmospheric parameters using Australian radiosonde network data , 2009 .

[21]  Perry J. Samson,et al.  Extreme Weather and Climate , 2010 .

[22]  Kefei Zhang,et al.  The beneficial impact of radio occultation observations on Australian region forecasts , 2010 .

[23]  M. Hagen,et al.  On the relationship between water vapour field evolution and the life cycle of precipitation systems , 2011 .

[24]  Witold Rohm,et al.  The verification of GNSS tropospheric tomography model in a mountainous area , 2011 .

[25]  Fabian Hurter,et al.  4D GPS water vapor tomography: new parameterized approaches , 2011 .

[26]  J. Saastamoinen.  Atmospheric Correction for the Troposphere and Stratosphere in Radio Ranging Satellites , 2013 .