Terminology

Wind Climate

Using PyWAsP for resource assessment involves working with different kinds of wind climate objects. This glossary clarifies the distinctions between them.

Time Series Wind Climate: A wind climate represented as a time series of wind speed and direction measurements. It is typically derived from an anemometer or meteorological mast, providing detailed information about the wind conditions over time.
Binned Wind Climate: A wind climate represented as a multidimensional histogram of “counts” or “frequency”. Typically, it consists of counts of occurrences in 12 sector bins (each representing a 30-degree wind direction) and 30 or more wind speed bins (typically 1 m/s wide, starting from 0.0 m/s).
Histogram Wind Climate: Synonymous with a Binned Wind Climate.
Weibull Wind Climate: A wind climate where the wind speed distributions are represented by Weibull distribution parameters. These are typically two-parameter distributions with a shape parameter (‘k’) and a scale parameter (‘A’). Most often, they consist of 12 sectors, each with its own ‘k’ and ‘A’ value.
Observed Wind Climate: A wind climate observed at a specific position, either from a meteorological mast or a grid point in a weather model. It can be represented as a time-series, histogram, or Weibull wind climate.
Predicted Wind Climate: Similar to an observed wind climate, this represents the local wind climate at a specific location. In WAsP, it describes wind climates modeled from a generalized wind climate to a new location. A predicted wind climate is most often represented by sector-wise Weibull parameters (a Weibull Wind Climate) but can also be a histogram (Binned Wind Climate).
Generalized Wind Climate: A wind climate that has been generalized using a flow model to remove local effects caused by terrain characteristics. This makes it representative of a larger geographical area, assuming a constant surface roughness. In WAsP, a generalized wind climate is typically represented by sector-wise Weibull parameters for several generalized surface roughness classes and heights above ground.
Geostrophic Wind Climate: A wind climate that represents the geostrophic wind, which is the theoretical wind that would result from a balance between the Coriolis force and the pressure gradient force. It is often used as a reference for understanding large-scale wind patterns.

Topography

The subtle differences between “topography”, “terrain”, “orography”, and other related words can be confusing. They are often used interchangeably, including in this guide. However, this is the terminology we strive to adhere to:

Topography: The detailed description and mapping of an area’s surface features, including land shape, elevation, and the location of natural and man-made features.
Terrain: The physical features of a piece of land, such as its hills, valleys, and bodies of water.
Orography: The study of mountains and mountain ranges, including their formation, structure, and distribution.
Elevation: The height of a point or object above a reference level, such as sea level.
Displacement height: The height above the surface to set the zero height level for wind measurements, typically used in the context of forest modeling. It accounts for the height of obstacles like trees or buildings that affect wind flow.
Surface roughness: Variations in the Earth’s surface that affect wind flow. This includes natural features like hills, valleys, and vegetation, as well as man-made features like buildings and structures.
Land use: The purpose for which a piece of land is used, such as for agriculture, housing, or industry.
Land cover: The physical material covering a piece of land, such as grass, trees, water, or pavement, including man-made structures. Land cover affects wind flow and helps identify areas suitable for wind energy development.
Vector map: A map that uses points, lines, and polygons to represent discrete geographic features like roads, rivers, and land cover types. Vector maps are precise and useful for storing and manipulating data in a Geographic Information System (GIS), making them common in wind resource assessment.
Raster map: A map that uses a grid of cells (pixels) to represent geographical information. Each pixel has a value corresponding to a feature or attribute. Raster maps are ideal for displaying data that varies continuously across a landscape, such as satellite imagery or digital elevation models.

WAsP

WAsP Method: The process of generalizing an observed wind climate and downscaling it to new locations using the WAsP flow model.
WAsP Model: A flow model that uses a collection of fast, linearized submodels to capture the effects of orography, surface roughness, and atmospheric stability on the wind.
WAsP Program: A Windows GUI program that interfaces with the WAsP core library, which includes the WAsP flow model.
WAsP Bundle: A collection of WAsP-related software, including “WAsP”, “WAsP Engineering”, “Terrain Editor”, “Wind Analysis Tool”, and others.
WAsP Engineering: A WAsP program specifically for site assessment.
WAsP CFD: A RANS-based method that combines EllipSys3D with the WAsP method for improved accuracy in complex terrain.

LINCOM

LINCOM Model: LINCOM is a fast linearised and spectral wind flow model for use over hilly terrain