Virtual Measurement Mast

A most advanced meso-scale modelling technique to simulate wind measurement time series yielding results close to real on-site measurements

Advanced re-analysis for modelling of historic weather data and for wind resource forecasting 

At any point (i.e. at the virtual measurement mast location) within a planned or existing wind park, we provide a wind data time series and the resulting wind statistics. Furthermore for the entire wind park area and its surrounding wind data time series at a 3km x 3km mesh wide are provided. 

For virtual measurement mast calculations we rely on more than 30 years of historic wind data that are based on meso-scale modelling. 

The virtual measurement mast (VMM) calculations are based on WRF (Weather Research and Forecasting Model), a most advanced meso-scale weather model whose quality has been proven in a large number of scientific publications. WRF has been applied and tested for many different weather conditions and has been used for all regions of the World and in about 130 countries. WRF enables high-resolution results in time and space, in order to yield best wind data close to results of on-site measurement masts. 

Utilized for meso-scale wind maps, micro-scale wind maps in junction with advanced CFD and for simulations of measurement masts 

A major objective of the VMM technique is the provision of a sound and most reliable base of wind data in order to finally estimate the financial returns and the volatility of the cash flow in a best possible way. Therefore the VMM results are used as data source for long-term alignment of energy yield prognoses. 

Alternative utilization purposes are the calculation of meso-scale wind maps, as well as micro-scale wind maps, if run in combination with a flow model like WASP or OpenFOAM (CFD). 

Next to the long-term time series modelled at any point of interest (the VMM location) we provide a set of data with horizontal resolution of 3km by 3km (wind speed and wind direction) as true 10-minutes average values. Default wind speed and wind direction data at provided at different selected heights. Temperature and pressure data are provided at each one of these selected heights. These resulting wind data time series are closest to observations of measurement masts installed on-site. 

The wind data derived most frequently are used as long-term reference for any site in the World, complying also with WMO requirements regarding wind data used for long-term reference. 

During VMM calculations WRF is used to re-analyse the wind conditions of the past. WRF provides historic wind data at the location of a wind park. Extrapolation of this long-term historic data enables forecasts of the wind resources at any site. 

How is it done? 

For VMM calculations WRF is used with a grid size of 3km. The model calculates the state of the atmosphere during the course of the year. It considers the full physics of the motion of air and estimates the transport of other constituents of the atmosphere as well: the evaporation of water from the soil into the air, the formation of water droplets in clouds or the fall-out of rain, snow or ice. Several other atmospheric processes are kept into account when running the WRF model. 

At the end WRF model performs a „dynamic down-scaling“. This means that the meso-scale calculation state of the atmosphere is large-scale weather patterns. For the purpose of wind mapping and Virtual Measurement Masts calculations, ERA-Interim (European Centre for Medium-Range Weather Forecasts (ECMWF)) is used as global re-analysis input. This global re-analysis data prescribe the coarse weather conditions, which will be re-fined by the WRF model. ERA-Interim comprises meteorological information of the wind, temperature, humidity etc. on a grid of about 50km and every 6 hours. WRF re-fines this meteorological information and produces an output with 3km resolution.

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