Summary

Add Quantile-Quantile (Q-Q) analysis for evaluating how well WeatherGenerator captures extreme values and distribution tails in high-resolution/downscaled fields.

Motivation

Coarse-resolution models smooth extremes via spatial averaging. High-resolution/downscaling should recover these extremes (e.g. heavy precipitation, wind gusts, temperature anomalies).
Q-Q analysis enables direct evaluation of distribution tails (90th–99.9th percentiles) between forecasts and observations.

Scope

Implement a Q-Q based evaluation metric for:

• Heavy-tail validation
• Extreme percentile comparison
• Distributional consistency checks

Priority

Medium