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Delegates are invited to meet and discuss with the poster presenters in this topic directly after the session 'The model chain: First steps towards tomorrow's technology' taking place on Thursday, 13 March 2014 at 09:00-10:30. The meet-the-authors will take place in the poster area.

Matthias Mohr Uppsala University, Sweden
Co-authors:
Matthias Mohr (1) F P
(1) Uppsala University, Uppsala, Sweden

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2014 and are published here unedited

Dr. Matthias Mohr is a research meteorologist at Uppsala University. He is working within the national research projects Wind Power in Forests, Sound from Wind Turbines (Model-Validate-Measure) as well as STandUP for ENERGY. His work concerns meteorological aspects of wind power, focusing mainly on mesoscale modelling. Prior to working at Uppsala University, Matthias Mohr was working at the Norwegian Meteorological Institute producing daily maps of temperature and precipitation using geo-statistics to spatially interpolate weather observations. Before that, Mr Mohr was working with very-high resolution mesoscale wind mapping at RES in Glasgow.

Abstract

Wind energy estimation over forest canopies using WRF mesoscale model

Introduction

Latest wind resource mapping over Scandinavia shows that forested areas have a substantial wind resource. However, forests increase turbulence and wind shear which enhances turbine loading and results in lower capacity factors. These key issues cannot be properly modelled by existing mesoscale models. Specific problems with mesoscale models are how to implement and describe forest edges, clearings and scattered forests or trees.

Approach

The most common approach to estimate the wind potential over forests is the use of CFD models that have high accuracy compared to simple linear models. CFD models have the capability to capture non-linear dynamics and atmospheric stability. However, CFD models are currently only used at the wind turbine siting stage and not at the resource assessment stage.
In this study, a forest canopy is implemented in the WRF mesoscale model in order to investigate the capability of a mesoscale model for wind resource assessment over forested areas.

Main body of abstract

Forest parameterizations in WRF or alternatively a full forest canopy version of WRF will broaden the usage of the model both in the wind farm industry and in the research community. A forest canopy model might lead to a better estimation of the energy yield and turbine loads already at the resource assessment stage. The model is validated using industry standard CFD models as well as measurements from a typical Swedish forest. In contrast to CFD models, mesoscale models allow a full simulation of all stability classes by simulating the complete diurnal cycle. Stability is believed to be a key factor in deteremining the turbulence and wind field above forests, especially at high latitudes, such as in Scandinavia. Analysis of measurements shows that stable situations are by far outweighing all other stability classes in Sweden. This might lead to a situation where forest effects are confined to lower elevations as otherwise expected.

Conclusion

The same parameterisations that are currently used in CFD models can be used in mesoscale models. This allows for a better representation of forest edges, clearings and scattered forests and trees. Especially at very high horizontal resolution the inclusion of a forest canopy model should be benificial to wind resource assessment and turbulence prediction.


Learning objectives
The audience should get an insight into forest canopy modelling in numerical models, such as CFD models and mesoscale models. The audience should get an understanding about how forest is implemented in mesoscale models.