Ancora simulazioni sulla nube radioattiva di Fukushima in giro per il mondo

photo nilu.no

Un'altra agenzia, Nilu-Atmos, ha preparato una simulazione del tragitto delle nubi radioattive provenienti da Fukushima, in collaborazione con ZAMG. Sia chiaro che queste sono simulazioni altamente incerte, che i dati sono pochi e che si sta tratteggiando lo scenario nell'ipotesi peggiore, e lo dicono anche gli autori con questo avviso

ATTENTION: These products are highly uncertain based on limited information for the source terms. Please use with caution and understand that the values are likely to change once we obtain more information on the overall nature of the accident. The products should be considered informational and only indicate 'worst case scenario' releases. From what we've learned recently, it seems releases of this magnitude have not yet occurred. Furthermore, these modeling products are based on global meteorological data, which are too coarse to provide reliable details of the transport of the plume across Japan. 

Il Nilu è  The Norwegian Institute for Air Research. Insieme alle previsioni (che, ricordo, causa insufficienza dei dati, sono solo a titolo informativo e tratteggiano l'ipotesi peggiore)  fornisce anche alcune informazioni sui modelli utilizzati.

"Five-day forecasts are provided to support scientific field campaigns. Normally, they are updated once a day, but during large experiments the system can be run four times a day.

 The meteorological fields (geopotential height at 500 hPa, surface pressure, equivalent potential temperature, CAPE, and vertical velocity at 500 hPa) are extracted from the Global Forecast System (GFS) data of the National Centre for Environmental Prediction (NCEP)

The trajectory forecasts are calculated with the trajectory model FLEXTRA based on Global Forecast System (GFS) data of the National Centre for Environmental Prediction (NCEP). 8-day backward and 4-day forward trajectory forecasts are provided for two locations. Trajectories are started every 500 m in the vertical and every 3 hours.

Emission tracer forecasts are calculated with the particle dispersion model FLEXPART based on Global Forecast System (GFS) data of the National Centre for Environmental Prediction (NCEP). Tracer masses are carried by particles following trajectories calculated using the GFS winds and stochastic components for turbulence and convection. Tracer forecasts are run separately for anthropogenic emissions from Asia, Europe and North America. For each of these forecasts, three tracers are available: carbon monoxide, nitrogen oxides (expressed as NO2), and sulfur dioxide (including direct emissions of sulfate). These species are run as passive tracers for a duration of 20 days, after which tracer particles are dropped from the simulation. In addition, a biomass burning CO tracer is available; the emission algorithm ingests actual information on MODIS fire detections, landuse information, and emission factors."

In questa pagina ulteriori notizie sui modelli utilizzati. Questa qui sotto è l'immagine con le varie animazioni (cliccate sull'immagine poi sulle frecce blu)

fonte nilu.no