a-urq / ecape

Calculate the entraining CAPE (ECAPE) of a parcel

ecape

ecape is a simple module that contains an entraining CAPE, or ECAPE, calculation described by Peters et. al. 2023. Peters-provided MatLab scripts serve as a reference and test verification data. The module leans heavily on MetPy for meteorological calculations.

Installation & Use

In console:

pip install ecape

See the example in linked documentation.

   from ecape.calc import calc_ecape
   ...
   ecape = calc_ecape(height, pressure, temperature, specific_humidity, u_wind, v_wind)

Documentation & Source

https://github.com/citylikeamradio/ecape

https://citylikeamradio.github.io/ecape

Contact

• Robert Capella
• [email protected]
• https://twitter.com/minusthebob

Questions, comments, and feedback are certainly welcome. This project is a personal exercise in learning how to publish packages to Github & PyPI, so excuse the excessive documentation for one function.

Future Work

• add support for other water content variables
• if useful, incorporate into MetPy
• provide cli .nc, .csv, & aws support

A note on undiluted CAPE & calculation accuracy

If users prefer their own CAPE calculations, use the undiluted_cape parameter:

When comparing calc_ecape.py & COMPUTE_ECAPE.m run on Peters 2023 sample data, there is a ~10% difference in the resultant ECAPE. This is almost entirely due to a difference in calculated MUCAPE. The tests describe other sources of variation (~1%).

Given:

• the methods here are within ~1% of Peters' calculations when undiluted CAPE is equivalent
• Peters et. al. specifically mention MetPy for determining undiluted CAPE
• MetPy is a reliable, open-source, and frequently used meteorological calculation package

MetPy's undiluted CAPE calculations were chosen for ease of readability and implementation.

References

Ryan M. May, Sean C. Arms, Patrick Marsh, Eric Bruning, John R. Leeman, Kevin Goebbert, Jonathan E. Thielen, Zachary S Bruick, and M. Drew. Camron. Metpy: a Python package for meteorological data. 2023. URL: Unidata/MetPy, doi:10.5065/D6WW7G29.

John Peters. ECAPE scripts. 2 2023. URL: https://figshare.com/articles/software/ECAPE_scripts/21859818, doi:10.6084/m9.figshare.21859818.v4.

Peters, J. M., D. R. Chavas, C. Su, H. Morrison, and B. E. Coffer, 2023: An analytic formula for entraining CAPE in mid-latitude storm environments. J. Atmos. Sci., https://doi.org/10.1175/JAS-D-23-0003.1, in press.

Licence

ecape is distributed under the terms of the MIT license.