NCAR / NCAR/wrf-python

SRH calculation values overestimated

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Dominant language
Python
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Description

Using the SRH calculation in wrf-python and also NCL (I think they are equivalent), I have found that the SRH values that I am getting are too large when compared to values computed in MetPy and those on observed soundings and in operational model output. After parsing through the source code (wrf_relhl.f90), I think that this overestimation is due to the estimation of the storm motion, which is assumed to be 0.75 * the mean wind over the 3-10 km layer and 30 degrees to the right of this vector. Since most other methods of computing SRH rely on the Bunkers storm motion, which is related to the mean wind over the ~0-6 km layer, I think that the values output in this routine would be quite a bit larger than what is standard as they accumulate through the integration. Would it be possible to update this code using the Bunkers calculation?

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Research direction

Start in wrf_relhl.f90 and trace the current SRH integration and storm-motion estimate: the issue identifies the 3–10 km mean wind, 0.75 factor, and 30-degree offset as the suspected source. Compare that approach with the requested Bunkers calculation based on the roughly 0–6 km layer. Done means the routine uses the agreed storm-motion method and its SRH values can be compared against MetPy, observed soundings, and operational model output.

Written by the indexing model from the issue text.

Assessment

Tech stack
fortran, python
Domain
data
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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