Dr Jonathan Jones is head of Global Navigation Satellite System meteorology research and development work for the Met Office.
The delay of a Global Navigation Satellite System (GNSS) signal between the satellite and a ground based GNSS receiver depends, after elimination of ionospheric effects, on the integral effect of the densities of dry air and water vapour along the signal path. The total delay in the signal from each satellite is known as the slant delay as the path is most likely to be non-azimuthal. As there are too many unknowns in the direct slant path, the signals are mapped up into the vertical (or zenith) by way of mapping functions which reduce the error budget to a level which may be resolved. This new parameter is known as the Zenith Total Delay (ZTD). ZTD gives a measure for the integrated tropospheric condition and is now widely accepted as a standard product from a network of dual frequency GNSS receivers. With further calculation, taking into account surface pressure and temperature, a portion of the ZTD can be converted into an estimate of the Integrated Water Vapour (IWV) content of the atmosphere.
IWV can change rapidly on a very short timescales. As such, the speed at which IWV can be calculated is of critical importance to short term meteorological forecasting (nowcasting). Often, rapid changes in IWV are associated with extreme weather, such as convective initiation and thunderstorm activity. Extreme weather events are typically difficult to predict and track under current operational meteorological systems and, as they have the potential to cause great damage, it is in the interests to both the public and National Met Services to significantly improve nowcasting wherever possible. As such, the requirement for dense, real-time GNSS networks for meteorological applications becomes apparent. Furthermore water vapour is one of the most important constituents of the atmosphere as moisture and latent heat are primarily transmitted through the water vapour phase. As well as this, water vapour is one of the most important greenhouse gases, and as such accurate monitoring of water vapour is of great importance to climatological research.
Jonathan has worked for the Met Office for over 10-years developing his GNSS expertise incorporating a strong blend of academic, commercial and cross government understanding through current and previous partnerships. Jonathan has both technical and GNSS processing expertise and has successfully delivered the operational GNSS-meteorology project and product management as well as partner channel expansion for the Met Office.
Jonathan has acted as peer reviewer for a number of international scientific publications, has presented his own work at numerous large international conferences and has authored/co-authored a number of articles and reports;
Jonathan holds a PhD from the Nottingham Geospatial Institute (formerly the Institute of Engineering, Surveying and Space Geodesy) at the University of Nottingham, and also holds a BSc (Hons) in Environmental Geoscience from Cardiff University.
Last updated: 8 April 2014