I am attempting to convert NAM grid data into a simple lat/lon grid that my current MERRA2 data is on (NAM Grid Info). The NAM data is currently in lat/lon but on a Lambert Conformal Projection. I've tried a few other posts with regards to converting coordinate using pyproj (SE Post 1,SE Post 2), but with no luck. Below is some sample data and what I have tried.

from pyproj import Proj, transform
lat = np.array([12.19, 12.2199, 12.2497, 12.2795, 12.3092])
lon = np.array([-133.459, -133.354, -133.249, -133.144, -133.038])

nam = Proj('+proj=lcc +lat_1=12.190, +lon_0 = -133.459 +datum=NAD83 +no_defs')
merra2 = Proj('+proj=longlat +datum=WGS84 +no_defs')

x, y = nam(lon, lat, inverse=False)
x2, y2 = transform(nam, merra2, x, y)

And x2, y2 give me the same result as lat/lon. Am I missing something? I should note I am fairly new to geographic transformations. Let me know if you need any other information.

1 Answer 1


I am overthinking this I believe. Since both grids are in lat/lon, I can begin comparison of different variables between the datasets. Below is an example screenshot of how the grids overlap.

NAM vs. MERRA2 grid

All I need to do now is figure out the best interpolation method to compare variables between the grids. For example. nearest-neighbor, bilinear, etc.

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