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How do I grid directional data, such as wind speed and direction, in Surfer?

If you have wind speed, wind direction, and some Z value (i.e. concentration), you can grid and display this data by converting the wind speed and direction to Cartesian XY coordinates, using the sin and cos functions in the worksheet.  If wind direction is measured clockwise from north:

X = r*sin(d2r(a))

Y = r * cos(d2r(a))

where:

X = new X component (eastings)
Y = new Y component (northings)
r = wind speed
a = wind direction (0° = north, 90° = east)
d2r = converts degrees to radians for the worksheet sin and cos functions.

Once you calculated the new X and Y values for each point, click Grids | New Grid | Data, select the data file and click Open. Choose to grid the X, Y, and Z (i.e. concentration) data, select any other gridding parameters you wish, and click OK. Now you can use the grid file to create maps.

Alternatively, if you have X, Y, speed and direction data, and wish to create a vector map, you can:

  1. Click Grid | Data, select the data file and click Open.
  2. Choose to grid the X, Y and speed data, select any other gridding paramaters you wish, and click OK.
  3. Click OK in the Surfer dialog telling you the grid was created.
  4. Click Grids | New Grid | Grid Data again, select the same data file and click Open.
  5. Choose to grid the X, Y and direction data, select any other gridding parameters you wish and click OK.
  6. Click OK in the Surfer dialog telling you the grid was created. 
  7. Click Home | New Map | Specialty | 2-Grid Vector, select the first grid and click Open, select the second grid and click Open

 See also: How do I create a vector map in Surfer with magnitude and direction arrows at the data points?

Updated February 3, 2017

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