I'm trying to plot U and V vectors in ArcGIS. I followed the method:
http://blogs.esri.com/esri/arcgis/2013/07/17/displaying-speed-and-direction-symbology-from-u-and-v-vectors/
In which, point no. 7) Choose in the drop-down list was not available in 9.3 version.
To do this in other way, I added a field in the attribute table "Rotation".
Using Filed Calculator, I tried the 'function' written in point no. 9)
9). Specify one of the following expression:
Oceanographic Convention: (180/3.14) * Atn2([u],[v])
Meteorological Convention: (180/3.14) * Atn2([u],[v])+180
It was failed due to error in the code.
What is the correct code to write the "Oceanographic Convention: (180/3.14) * Atn2([u],[v])"?
Or is the any other way to plot in Arc?
Thanks.
If you plot data from excl, maybe the problem is linked to the excl, in this case you need to convert angles from degrees to radiant, furthermore, excl reed the angles in a opposite direction with respect the wind chart, thus each angle value (alfa) should be transformed in 90-alfa before the conversion.
Try MGET tool http://mgel.env.duke.edu/mget/ . It has a python script to get mag/direction vector from u v vector component rasters. Hope this solves your problem
Sorry if this question comes late as this questions should be solved months ago. I have installed MGET, but I cannot find the python script to get the mag/direction, where is it please? Thanks!
I don't know about ArcGIS 9.3, but in 10.3 following the blog works perfectly for displaying direction from u and v in a table. You could display the arrow size as the magnitude (100 * Sqr ( [u] * [u] + [v] * [v] )) --- 100 just for sizing, so it's visible on my display with my specific numbers. The only drawback, you can't display in color.
For graduated color display you'd need the value of magnitude and direction in your table. I calculated the direction using field calculator as shown in the jpg
when field calculator opens the parser is defaulted to VB script (no atn2() available), you need to click the radio button to Python, then you will find the Atn2() function (and a pi function as well --- see jpg)
In case you can't see the jpg: direction = (180 / math.pi) * math.atan2( !u!, !v! )
Note: the result will be positive (for u>0) and negative (for u
may be you can use Surfer software. its better than Arc GIS for plotting U and V wind .
See this page (https://marinedataliteracy.org/ops/ss_height/ss_height.htm) for mapping of SSHa and geostrophic current magnitude and direction.
Hello,
The two attached links will help you a lot.
You need to use the Raster calculator by entering the following formula:
(180/3.14) * ATan2([u],[v])+180
Then, transform each pixel of the raster into a point, in order to represent it as an arrow to indicate the wind direction.
Good luck!
1- https://www.esri.com/arcgis-blog/products/product/analytics/displaying-speed-and-direction-symbology-from-u-and-v-vectors/
2- https://giscrack.com/how-to-create-a-wind-map-in-arcgis/
Warm Regards,
Abdi-Basid ADAN
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