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Data: Era interim 10m wind component U and V
Software:matlab2014b, Arcmap10.3
1. compute the wind speed and direction in matlab:
speed=sqrt(u.*u+v.*v)
angle=(180/3.14)*atan2(v,u)note that the angle now is just arithmetic angle and we should convert the arithmetic angle to geographic angle before plot in arcmap
conversion:
angle=rem(450-angle,360)2.add the wind data with lat, lon, speed and direction fields in Arcmap, the step by step processes about how to display the wind vector had been illustrated by Kevin Butler (Displaying Speed and Direction Symbology from U and V vectors) https://www.esri.com/arcgis-blog/products/product/analytics/displaying-speed-and-direction-symbology-from-u-and-v-vectors/
3. The formulas above are correct only if U and V are measured relative to a grid where true north consistently points straight up (e.g. no rotation). Otherwise, a convergence angle correction must be applied based on the projection of the data
4. Convergence correction in Arcgis:
Arcgis tool box: Cartography Tools->Data Driven Pages->Calculate Grid Convergence
1)Select the field to calculate the convergence (usually add a new field in the attribute table)
2)Set the envrionment to specify the projection coordinate:
3)output corrdinate
4)Cartography
5)original wind vector without correction
6)set the rotation as original angle plus convergence correction
7)wind vector with grid convergence correction
