MeteoSwiss - CN-MET

Introduction

Main purpose of the CN-MET project (Centrale Nucléaire et METéorologie) is to bring up to date the system delivering weather information necessary to the population safety in case of a nuclear hazard. CN-MET represents the coupling of a specifically adapted measurement network and a predictive tool in the form of a fine grid numerical weather prediction model currently developed at MeteoSwiss (COSMO-2). This new tool, calling upon modern measurement and modeling techniques of the atmosphere, represents a solution which will keep all its relevance for the next decades.

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 prevention for the concerned population on a local scale, but also enhances it on a regional scale corresponding to the Swiss Plateau.

The measurement network

With the CN-MET project a new measurement network (cf. Figure 1) is being set up which includes:

three remote sensing sites measuring wind and temperature profiles within the Planetary Boundary Layer (PBL), respectively downwind, upwind and in the center of the domain (cf. Figures 2 and 3), and a fourth station (in complex orography) for wind measurements in the first hundreds of meters above ground,

surface weather stations from the new SwissMetNet (SMN) network (with additional turbulence measurements) at each of the four nuclear power plants,

four SMN Surface 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).

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

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.

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

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

As a part of the CN-MET project, a new fine-grid numerical weather prediction model (cf Figure 4), COSMO-2, is being developed, with the following caracteristics:

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 (HSK; Hauptabteilung für die Sicherheit der Kernanlagen) for short-distance dispersion calculation around the Swiss nuclear power plants
providing an 18 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 HSK, with an hourly computation of an analysis and a short-range forecast, in order to satisfy the high requirements of a diagnostic tool.

Example of a simulated wind field displayed with WMO wind barbs.

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

Conferences

CIMO, March 2005

CIMO05windprofiler.pps, 14.6 MB

TECO, Mai 2005

TECO05projetCN-MET.pps, 9.4 MB

AMS, January 2006

AMS06projetCN-MET.pps, 21.2 MB

Contacts

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
Yves-Alain Roulet, project management, MeteoSwiss, Aerological Station, P.O. BOX 316, 1530 Payerne, Switzerland