Enhance Grid-Stat to compute SEEPS for gridded observations and write the SEEPS STAT line type.

[RachelNorth]

Describe the New Feature

The Stable Equitable Error in Probability Space (SEEPS) score is described in Rodwell et al. (2010) and was devised for evaluating quantitative precipitation forecasts against SYNOP gauge data at (but not limited to) station locations. It uses a climatology to account for local variations in rainfall which enables aggregation over otherwise heterogenous locations. Recent work (North et al., 2021) has used a gridded product for calculating the score over both land and sea areas.

This issue will act as an umbrella ticket for the implementation of the gridded score capability.

• MET Enhance Point-Stat to compute SEEPS for point observations and write new SEEPS and SEEPS_MPR STAT line types. #1942 added SEEPS to Point-Stat.
• MET Enhance Series-Analysis to compute statistics from the SEEPS STAT line type. #2269 will add it to Series-Analysis after this one is completed.

While Point-Stat writes the SEEPS and SEEPS_MPR line types, Grid-Stat should only write the SEEPS line type. However, recommend also adding support for:

nc_pairs_flag = {
...
    seeps = TRUE;
...
}

There setting the nc_pairs_flag.seeps setting enables some output to be written to the "_pairs.nc" file created by Grid-Stat. At a minimum, it should write the seeps value for each grid point.

Please talk to @RachelNorth to determine if any other columns from the SEEPS_MPR line type should also be written to the "_pairs.nc" NetCDF file.

We do still need to define the columns that should be included in a new SEEPS line type.
MET #1942 left the S12 through PV3 columns set as NA. Work for this issue should actually define their contents.

Acceptance Testing

List input data types and sources.
Describe tests required for new functionality.

Time Estimate

Estimate the amount of work required here.
Unknown

Sub-Issues

Consider breaking the new feature down into sub-issues.

• Add a checkbox for each sub-issue here.

Relevant Deadlines

Part of Met Office contract, ending August 2022 MET v11.

Funding Source

2799991

Define the Metadata

Assignee

• Select engineer(s) or no engineer required: @hsoh-u
• Select scientist(s) or no scientist required: @RachelNorth

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Define Related Issue(s)

Consider the impact to the other METplus components.

• METplus, MET, METdatadb, METviewer, METexpress, METcalcpy, METplotpy
• Need METplus issue to add output_flag.seeps and nc_pairs_flag.seeps as configurable options.

New Feature Checklist

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[JohnHalleyGotway]

Testing of MET-11.0.0-beta5 revealed a couple of issues with the SEEPS implementation. Reopening this issue to fix the following:

• seeps_p1_thresh is included in the Grid-Stat config file but not actually referenced in the code. Update Grid-Stat to use it.
• The SeepsClimo constructor is called and loads the climo data every time Point-Stat and Grid-Stat are run. This should be changed to only load the data when it is actually needed.