Describe the New Feature

In discussions with Gwen Chen from EMC, there seems to be an opportunity for expansion with MET's calculation of Anomaly Correlation Coefficient (ACC).

As it currently stands, ACC is calculated with the following equation:

Where f denotes the forecast, o for observation, and c for climatology. The (o - c) term is more simply the observation anomaly; likewise, the (f - c) term is the forecast anomaly.

During Sea Surface Height (SSH) verification within MET, Gwen noticed that the MET values for ACC were not matching the legacy system outputs (mismatch at approx. the tenths value). The legacy system is part of Todd Spindler's website, given here: https://polar.ncep.noaa.gov/global/class-1/ (view the SSH tab).
This was due to the MET calculation method and the datasets available: using the AVISO as the verification dataset, the Absolute Dynamic Topography (ADT) and Sea Level Anomaly (SLA) are the only variables available. ADT is instantaneous and cannot be used to verify SSH, and SLA is, as its name implies, an anomaly. In MET, the equation provided above does not allow any substitutions for the anomalies it calculates, instead using forecast-observation pairs and climatology.

Ideally, there would be a way for users to provide anomaly datasets (forecast or observation) and have those be substituted in the appropriate areas for statistics. Given the large coding overhaul that would require, it might be more prudent to create a new CNT column that calculates this alternative method of ACC.

The biggest hurdle to this is implementation. Even by restricting this to the tool currently being used for analysis (Grid-Stat), it would require another file input, regridding, and possibly more configuration options available to the forecast and observation fields.

Acceptance Testing

Gwen provided datasets for testing the functionality.
Forecasts come from RTOFS, Observations come from AVISO, and climatology is provided from HYCOM_NCEP. These are housed on Seneca, under /d1/personal/jopatz/workbench/ACC_work

Time Estimate

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Issues should represent approximately 1 to 3 days of work.

Sub-Issues

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Relevant Deadlines

This would ideally be completed before the EVS deadline of Dec. 1st, but with the current workload on MET and necessary lead time to get new features tested and loaded over to NOAA machines, that may not be an option.

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