coastx is a simple Python package for reprojecting latitude/longitude coordinates near the Texas coast into a linear, along-coast reference frame.
To build from source, clone this repository, navigate to the cloned directory, and then run the following in the desired environment:
python -m pip install .
Requirements: numpy, matplotlib, and xarray
For some (N,2) array degree_coordinates, which contains longitude in the first column and latitude in the second, convert to along-coast coordinates as follows:
import coastx
coastal_coordinates = coastx.transform(degree_coordinates)
The new array coastal_coordinates will contain distance_along_coast in the first column and distance_inland in the second. The units are still in degrees, but given that latitude and longitude do not strictly speaking have the same scale, the units should perhaps be considered pseudo-degrees. If you would prefer the units be pseudo-kilometers, multiply the entire array by a scaling factor of 111.28692.
The origin of the coastal reference frame is approximately the mouth of the Rio Grande. The distance_inland axis is approximately zero at the coastline, but in an attempt to minimize local distortion, is usually not exactly equal to zero. The actual reference surface is a smooth spline located about 30km offshore, and the distance_inland axis is defined to be locally orthogonal to that surface.
Note that any coordinates outside of the reference zone (either too far from the coastline or too far from Texas) will return as NaN.
The below example shows a coarsened version of the Pekel et al. water frequency map for Texas reprojected into the coastx reference frame.
Please feel free to open an issue or a pull request!