In case of a nuclear accident, the necessary atmospheric data used to calculate the diffusion of a contaminated air mass will be provided by a fine grid numerical model, covering the whole Swiss territory. The new measurement network within CN-MET is directly adapted to provide the best information (initial and boundary conditions, and test measurements) for this model. CN-MET not only ensures the emergency preparedness for the concerned population on a local scale, but also enhances it on a regional scale corresponding to the Swiss Plateau.
CN-MET Final assessment report, November 2009
The measurement network
- three remote sensing sites measuring wind and temperature profiles within the planetary boundary layer (PBL), located downwind, upwind and in the center of the domain (data examples cf. Figures 2 and 3),
- surface weather stations from the new SwissMetNet (SMN) network (with additional turbulence measurements) at each of the four nuclear power plants,
- four SMN boundary layer stations in order to add information on wind and temperature measurement in the PBL, which are integrated in the MeteoSwiss measurement network.
Figure 1: The CN-MET measurement network, including 3 remote sensing sites (green), 4 SMN stations at the nuclear power plants (blue) and 4 SMN Surface Layer stations (red).
Figure 2: Top: Vertical temperature profiles measured on 18 March 2006 (time step of ca. 90 sec) with a microwave radiometer installed at the Aerological Station in Payerne. Bottom: Comparison with the sounding in Payerne at 00, 12 and 24 UTC; red: sounding, blue: radiometer.
Figure 3: Vertical wind profiles (speed and direction) measured on 23 May 2005 (time step of 30 min) with a wind profiler installed at the Aerological Station in Payerne. The wind profiler measurements of Payerne are available in real time from the U.K. Metoffice website.
The fine-grid model COSMO-2
- data assimilation from the above mentioned network for initial conditions, thus offering a complete and coherent image of the state of the atmosphere and its evolution (wind, turbulence, precipitation, etc)
- providing input data for the dispersion models in operation at the Swiss Federal Nuclear Safety Inspectorate (ENSI; Eidgenössisches Nuklearsicherheitsinspektorat) for short-distance dispersion calculation around the Swiss nuclear power plants
- providing an 24 hours forecast every 3 hours, with a 10 minutes output time step, for the whole Swiss Plateau
- providing an emergency mode, activated on demand by the ENSI, with an hourly computation of a short-range forecast, in order to satisfy the high requirements of a predictive emergency response tool.
Figure 4: Example of a simulated wind field on the Swiss Plateau obtained by the new fine grid model COSMO-2 with a horizontal resolution of 2.2 km. Background colour shading according to terrain height in the model.windfield_large.png, 44 KB
- Bertrand Calpini, CN-MET project leader, MeteoSwiss, Aerological Station, P.O. BOX 316, 1530 Payerne, Switzerland
- Dominique Ruffieux, responsible for the CN-MET measurement network, MeteoSwiss, Aerological Station, P.O. BOX 316, 1530 Payerne, Switzerland
- Philippe Steiner, responsible for the development of COSMO-2, MeteoSwiss, Krähbühlstrasse 58, 8044 Zürich, Switzerland
- Olaf Maier, project management, MeteoSwiss, Aerological Station, P.O. BOX 316, 1530 Payerne, Switzerland
- Pirmin Kaufmann, CN-MET operating manager, MeteoSwiss, Krähbühlstrasse 58, 8044 Zürich, Switzerland