"tide_elevations" Returning Masked NaN Values

[PriyanshusSGupta]

I'm trying to compute tidal elevations using pyTMD.compute.tide_elevations, but the output is returning masked NaN values. Below is my code snippet:

from pyTMD.compute import tide_elevations
import pandas as pd

tide_elevations(
    x=[122.21],
    y=[-18.20],
    delta_time=pd.date_range(start="2022-09-01", end="2022-09-02", freq="12h"),
    DIRECTORY="FES2022/FES2022",
    MODEL="FES2022",
    EPSG=4326,
    TIME="datetime",
    TYPE="time series"
)

Expected Output:
I expected to receive tidal elevation values for the given location and time range.

Actual Output:
The function returns a masked array with all NaN values:

masked_array(data=[[--, --, --]],
             mask=[[ True,  True,  True]],
             fill_value=nan,
             dtype=float64)

Troubleshooting Steps Taken:

Verified that FES2022 model files exist in the specified directory.
Confirmed that the longitude and latitude values are within the valid range.
Checked different time ranges but still got NaN results.
Questions:

Are there additional dependencies or preprocessing steps required to use tide_elevations correctly?
Could this be related to missing tide model data for the given coordinates?
How can I debug what’s causing the NaN values?
Any guidance would be greatly appreciated!

[tsutterley]

Try adding EXTRAPOLATE=True to the tide_elevations command. Can also try with the bilinear interpolation option instead of the default spline.

[PriyanshusSGupta]

Thank you so much for your help! 🙌 Adding EXTRAPOLATE=True and METHOD="bilinear" resolved the issue, and I’m now getting valid tidal elevation values. I appreciate the quick response and the detailed guidance.

This was really helpful, and I’ll keep these parameters in mind for future cases. Thanks again! 🚀