I am trying to create fishnet across the USA. In the end, I want to calculate summary statistics for the vegetation in each grid, as well as get the distance between the each cell's centroid and the ocean. The problem is that the USA spans several UTM zones. So I am not sure how to do this.

If I choose any one of the UTM zones, the grid cells would be distorted in the other zones.

I could try to create a set of fishnet for each UTM zone, join them, reproject them to WGS84, and use great circle distance to calculate distance from the ocean. But the fishnets would overlap at the borders. Since the overlaps won't match perfectly, choosing one fishnet over the other would result in some areas being counted twice or not counted.

If I use WGS84, the units would be in degrees. If I set the cell width to be say 1 degree, the cell size at lower latitudes would be larger than those in higher latitudes.

I wonder if I can use WGS84 but still use meters as the height/width unit for the cells. But so far I haven't found the way to do this in QGIS or Python.

I would be using the fishnet in Google Earth Engine in the end. So any ideas on how to solve this in Google Earth Engine, or creating the fishnet layer in Python or QGIS first, would be helpful.

  • 4
    Don't use UTM; use the CONUS USGS Albers Equal Area.
    – Vince
    Commented Oct 24, 2021 at 2:26
  • but i also need fishnet for Alaska, so the range would be around 30N - 70N. But according to ArcGIS doc, the total north-south range shouldn't exceed 30-35 degrees.
    – Sara
    Commented Oct 24, 2021 at 2:55
  • but indeed not using UTM seems like a good start. I found this post also gives some similar insight.
    – Sara
    Commented Oct 24, 2021 at 3:04
  • There's also a standard Albers that includes Alaska and Hawaii
    – Vince
    Commented Oct 24, 2021 at 3:38
  • I created a global 25 sq.km. fishnet by choosing an arbitrary latitude (near 32N), scaling a "square" cell at a fixed width of 5 sq. km. (yet evenly divisible by 360 degrees), then using the fixed width (in degrees) to generate fishnet cells within +/-0.01% of 25 sq. km. by altering the height, starting at the equator. Africa's cells are somewhat squat, and northern latitude cells in Europe and Canada are somewhat tall, but the 25 sq.km. cells are nearly as accurate as seven decimal places can provide. So you can use WGS84 if you want to do your modeling that way.
    – Vince
    Commented Oct 24, 2021 at 3:52


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