The subject of this manual is the use of satellite imagery in operational weather forecasting as well as in synoptic research in combination with other meteorological data, especially relevant numerical parameter fields. This combined use is a major requirement for an optimal detection of ongoing physical processes in synoptic research and an urgent need in operational forecasting to overcome the problem of an excessive amount of material on the forecasters bench.

The physical-meteorological evaluation of a combination of such different data like descriptions of image structures, irregular distributed point measurements from synoptic observations and numerical parameter fields on a defined grid is not a simple task. There is, however, one tool already widely used in synoptic research and operations - the Conceptual Model.

Examples showing the usefulness as well as a definition of conceptual models have been derived among European countries in the frame of the COST 78 action (Development of forecasting techniques):

Definition of conceptual models

The recommended way of synthesizing knowledge is by reference to the so-called conceptual model. Based on existing literature the following definition has been derived:

A conceptual model describes essential features of a meteorological phenomenon and identifies the principal processes taking place.

A complete conceptual model provides a:

• Definition of the phenomenon in terms of features recognizable by observations, analysis or validated simulations;
• Description of its life cycle in terms of appearance, size, intensity and accompanying weather;
• Statement of the controlling physical processes which enables the understanding of the factors that determine the mode and rate of evolution of the phenomenon;
• Specification of the key meteorological fields demonstrating the main processes;
• Guidance for predicted meteorological conditions or situations using the diagnostic and prognostic fields that best discriminate between development or non-development; guidance for predicting displacement and evolution.

Role of conceptual models for nowcasting

Conceptual models provide the meteorologist with:

• help in understanding and diagnosing phenomena
• a synthesis of all available information
• a 4-dimensional "mental picture"
• the basis for isolating weather processes
• the basis for extracting the main signals from complex patterns
• tools for support of the diagnosis of numerical models
• a supplement to numerical models for the nowcast time scale
• tools for identifying errors in the numerical forecast
• tools for modification of numerical products
• a fast forecast method
• an independent forecast method
• a forecast method particularly for hazardous weather
• the possibility of filling in gaps in the data

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