Describe the New Feature

As work continues in the marine and coastal verification area, the variable Scatter Index has been used more and more in the user Python code. As MET is already producing 99% of the variables calculated for marine and coastal verification, the addition of Scatter Index seems appropriate.

Scatter Index (SI) is calculated by

SI = 100.0*[ (avg((fcst-obs)^2)^0.5) - (avg(fcst-obs)^2) ] / avg(obs)

Acceptance Testing

Input data types and formats vary, but this should be first tested against ice cover data (netCDF4 format). A sample forecast and obs file are on Kiowa:

Fcst file: /d1/projects/MET/MET_test_data/ice_cover_ScatterIndex/20210305_rtofs_glo_2ds_n024_ice.nc
Obs file: /d1/projects/MET/MET_test_data/ice_cover_ScatterIndex/2021030512_UKMO_L4.nc
Python embedding: /d1/projects/MET/MET_test_data/ice_cover_ScatterIndex/ice_code_hera.py

Python script requires the following arguments to run:
Fcst_file Obs_file hemisphere file_indicator

Depending on the file indicator, the script will either pass the forecast field or observation field in memory for MET to utilize. Success of this issue is the return of the Scatter Index by MET in the CNT line type.

Time Estimate

Need estimate from engineer

Sub-Issues

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Relevant Deadlines

None

Funding Source

2788881

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Define Related Issue(s)

Consider the impact to the other METplus components.

• METplus, MET, METdatadb, METviewer, METexpress, METcalcpy, METplotpy
• Need to add issues for METdatadb to update the CNT line type and METviewer to plot this new statistic.
• Update database loader to handle new CNT columns for the Scatter Index. METdataio#61
• Enhance METviewer to plot new CNT columns for the Scatter Index. METviewer#317

New Feature Checklist

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