Overview and requirements for the COST-716 near real time demonstration 
project for Numerical Weather Prediction applications

Hans van der Marel
Delft University of Technology,
Department of Geodesy
Thijsseweg 11,
2629 JA Delft,
The Netherlands



In the framework of the European COST 716 action "Exploitation of 
Ground-Based GPS for Climate and Numerical Weather Prediction applications"
a near real-time demonstration project is scheduled for 2001. The 
current plans foresee in two one month test datasets, in the 
summer and winter of this year, preceeding the more continuous demonstration 
starting in 2001. 

The two datasets in 2000 will be used to test the dataflow from GPS 
receiver, to GPS analysis center(s) and into the regular meteorological 
datastream for numerical weather prediction (NWP). The main objective
of these tests is to make available two GPS datasets, in a format well
suited for meteorology and archived like all other meteorological data, 
that can be used to study and further develop assimilation of GPS data 
into NWP models. These datasets are intented to assist in preparing the 
assimilation process. The assimilation itself will not be tested - in near 
real-time - until 2001, when the second phase of the demonstration project 
starts.  

The GPS processing is organised around several near real-time networks
which contribute to this demonstration project. Some of these networks 
already exist, others are being set up at the moment. The networks are
free to organise the processing as they seem fit in order to get, what they
believe, the best possible results. The only requirements from the point of
view of COST 716 are, that each GPS processing center computes
properly validated Total Zenith Delays (TZD) with a well defined quality 
indicator, in one of the agreed formats. A significant amount of work
will be needed in order to derive a good quality indicator and to
understand the statistical properties of the TZD data. Various scenarios
for the combination of data, or not, will be tested. However, in order
to be of any use to NWP, the GPS derived zenith delays should be made 
available within 3 hours. 

     
More information can be obtained at the home page of the action 
(http://www.oso.chalmers.se/geo/cost716.html).