Description of the methodology used to generate the wind maps of Spain.
In the heart of MesoMap lies MASS (Mesoscale Atmospheric Simulation System), a numerical atmospheric model developed in the last 20 years by Meso Inc. (partner of Meteosim Truewind) as a tool for research, as well as a platform to generate meteorological commercial products. MASS simulates the physical phenomena which govern the atmosphere, applying in turn the fundamental conservation equations for mass, momentum and energy (the basic principles of Dynamics and Classical Thermodynamics). As well as that, the model has a kinetic turbulent energy module which takes into account viscosity and wind shear thermal stability. As a dynamic model, MASS simulates the evolution of atmospheric conditions in time steps of the order of a few seconds. This generates a strong demand of computational resources, especially when working at very high resolution.
Finally, MASS couples to a simpler and quicker model, WindMap, which is a mass conservation model that simulates wind flows by direction. Depending on the extension and complexity of the region, WindMap is used to improve the spatial resolution of simulations, and thus resolve more precisely the local topographic effects.
The model MASS is fed by different types of global, geophysical and meteorological databases. The main information sources come from reanalysis, rawinsondes, surface stations and soil characteristics.
3. Calculation and data storage systems
The MesoMap system needs a huge calculation and storage power to generate wind resource maps with high spatial resolution within reasonable time. To reach this target, 56 processors were used, which generated 3 Terabytes of information.
As every day simulated by a processor is completely independent from the rest of days, the project can be conducted in parallel by this system 56 times more quickly than using only one processor. In other words, a typical MesoMap project that would take more than two years to be completed by one processor can now be completed in two weeks.
4. Generation of wind resource maps
The MesoMap system generates the maps of wind potential in three steps. First of all, MASS simulates the atmospheric conditions representative of a period of 15 years. Every simulation gives values of wind speed, among other meteorological variables (such as temperature, pressure, moisture, kinetic turbulent energy and heat flow) in three dimensions within the integration domain. These data are saved in hourly outputs. As soon as the simulations are completed, results are compiled in summary files, which constitute the input to WindMap model in the second stage of map making. The final stage is transforming these numerical results into maps, which is done with the help of the tools provided by Geographical Information Systems.
Both the average annual characteristics of the wind vector and the mean annual wind power density are products of the microscale model, downscaled from the results of the mesoscale model. This means that they are exactly the variables calculated by MASS in the whole three-dimensional mesh for every integration step. From wind speed and air density, the local wind power density is retrieved at every point.
The two main final products of the whole process are:
The mapped speeds are compared to those coming from meteorological towers on the earth's surface or on the sea. In case significant differences are observed, final adjustments are performed.