Template:Quadratic Friction

The Quadratic Friction tool is used to populate the spatial attributes for the quadratic friction coefficient at the sea floor. A new dataset is created from NLCD, C-CAP, or other land use rasters.

The tool will extract values from the raster object specified by the tool. For each node in the geometry, the "area of influence" is computed for the node. The area of influence is a polygon that represents the area of the geometry around a node. This is computed as the area encompassing the node and half the distance to each of his neighboring nodes. All of the raster values within the area of influence are extracted from the visible raster objects. A composite quadratic friction value is computed taking a weighted average of all the raster values. If the area of the extracted values is less then the area of influence around the node (because we passed the extent of the raster objects or encountered null values), the default value is used to compute the quadratic friction using the area not represented in the values.

If the landuse type is chosen as NLCD or C-CAP, the following default values are used in the calculation. If you have a different landuse raster type, or wish to use values that differ from the defaults, you can specify the raster type as Custom and provide your own .csv file with the desired values.