It has recently been demonstrated that signals from the Global Positioning System (GPS) of navigation satellites can be used (in a supplementary role to their positioning and navigation function) as a remote sensing tool to estimate the integrated precipitable water vapour (IPWV) content of the atmosphere ('GPS meteorology'), potentially with sub-millimetre accuracy and 30 minute temporal resolution on an all-weather, world-wide basis. Such data would be of considerable benefit to both climate studies and weather forecasting. This proposal will create links with the user meteorological and climatological communities in order that the EO data obtained can be fully utilised. The techniques of GPS data processing will be examined with the aim of providing an optimum, automatic system for the routine retrieval of IPWV. The validation and calibration phase of the technique will involve the collaboration of several research centres and the use of Water Vapour Radiometer (WVR) measurements. The radiometer instrumentation hardware and software will also be examined within the scope of this proposal to provide the most accurate estimates of IPWV. More specifically, the proposals main objectives are to:
- Validate the accuracy and temporal resolution of GPS meterology, by comparison with ground-based water vapour radiometry (WVR), space-based radiometry (SSM/I) and radiosonde profiles,
- To assess the feasibility of near real-time, automatic estimation of IPWV from GPS to an accuracy of 1mm,
- To compute a post-processed data set of GPS IPWV estimates from a European sub-set of established permanent GPS monitoring stations (part of the International GPS Service (IGS) for Geodynamics network), for climate modelling studies and,
- To investigate the possibility of obtaining a more detailed tomographic profile of water vapour over a smaller, denser GPS network to provide a data set to study micro-scale synoptic processes.
As a result of this proposal we aim to provide data sets from which climatologists will be able to examine a number of key questions remaining in the field of climate study. The feasibility of using GPS IPWV estimates on a regional scale to constrain numerical weather prediction (NWP) will also be assessed. This research may also provide spin-offs in the field of Geodesy, since any improved atmostpheric modelling techniques developed for GPS will ultimately feedback into improved GPS positioning (in particular heighting) precisions.
Funding SchemeCSC - Cost-sharing contracts
439 00 Onsala