glm-output-parser

name	glm-output-parser
description	Extract and transform water temperature data from GLM NetCDF files, handling dynamic layering, masked arrays, and temporal alignment.

1. Time Alignment:

   • Extract the time variable from the NetCDF file.
   • Use the units attribute (e.g., "hours since 2009-01-01 00:00:00") and the &glm_setup start time to convert numeric time values into standard datetime objects.
   • Ensure the resolution (e.g., daily noon) is consistent for comparison with observations.

2. Dynamic Depth Calculation:

   • For every timestep, retrieve the vertical height array z and the temperature array temp.
   • Identify valid (non-masked) layers.
   • Calculate the surface height ($H_{max}$) for that specific timestep as the maximum value of z.
   • Calculate the depth for each layer: $Depth = H_{max} - z$.

3. Handling Masked Arrays:

   • GLM output often contains masked or fill values for inactive layers. Explicitly filter out these values from both z and temp before processing to avoid inclusion of invalid data in means or comparisons.

4. Data Structuring:

   • Store processed data in a format suitable for merging (e.g., a DataFrame) containing columns for datetime, depth, and temp.