The ECMWF Global Model
Meteorology student Carola was lucky to get a job as meteorology assistant during the summer months. Her advisor, forecaster Christian, is introducing to her the basic meteorological material in use and is explaining the usual forecast techniques.
"One of the most basic and necessary tools for forecasting are the forecast products of global numerical models. Usually weather services receive the output of the model in form of numerical datat at gridpoints. Each weather service computes and visualizes from these basic data charts of their interest. I show you the derived products we are using at ZAMG. If you had your practicum in a different weather service you may find different products. But the basic idea behind this material is everywhere the same and if you have understood the principal you can apply it on similar charts."
These are the charts we are computing from the global model ECMWF which is in use in many weather services.
The characteristics of global models are:
- Model domain: global
- Space resolution: 30 km
- Time resolution: 2 runs per day; 6 hourly charts
- Forecast period: 5 days (also 10 days possible)
The forecast ist the result of a mathematical dynamical model: Atmosphere and the physical processes going on are formulated in form of the equations derived in physics. As neither these contained processes nor the actual measurements initialising the model can be complete, the forecasts are of course incomplete and erraneous. The longer the model is forecasting the less is the skill of the model. On the other hand are those models the only information about the processes taking place in the near future.
"What is the quality of this global model?"
"The quality is assessed in various ways. I'll tell you about that later."
"Now, let's continue with the local area model. Follow
this link
to find out about it!"