Update generate-percentiles Doc String (#1923)

* Clarifys docstring of generate-percentiles regarding mask_percentiles option * Updates doc string following review --------- Co-authored-by: Marcus Spelman <[email protected]>
metoppv · Aug 3, 2023 · 6a82518 · 6a82518
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diff --git a/improver/cli/generate_percentiles.py b/improver/cli/generate_percentiles.py
@@ -86,8 +86,19 @@ def process(
             percentile and the ECC bound.
         mask_percentiles (bool):
             A boolean determining whether the final percentiles should
-            be masked. This is only implemented to work when converting
-            probability cubes to percentiles.
+            be masked. If True then where the percentile is higher than
+            the probability of the diagnostic existing the outputted
+            percentile will be masked.
+            This masking acts to cap the maximum percentile
+            that can be generated for any grid point relative to the
+            probability of exceeding the highest threshold at that point.
+            For example, if the probability of a temperature exceeding 40C
+            is 5%, the 95th and above percentiles will all be masked.
+            Likewise, if at some grid point the probability of the cloud base
+            being below 15000m (the highest threshold) is 70% then every
+            percentile above the 70th would be masked.
+            This is only implemented to work when converting probabilities to
+            percentiles.
         optimal_crps_percentiles (bool):
             If True, percentiles are computed following the
             recommendation of Bröcker, 2012 for optimising the CRPS using

diff --git a/improver/ensemble_copula_coupling/ensemble_copula_coupling.py b/improver/ensemble_copula_coupling/ensemble_copula_coupling.py
@@ -519,6 +519,9 @@ def __init__(
                 The probability of being below the final threshold in
                 forecast_probabilities is used as the probability of the diagnostic
                 existing.
+                For example if at some grid square the probability of cloud base
+                being below 15000m (the highest threshold) is 0.7 then every percentile
+                above the 70th would be masked.
             skip_ecc_bounds:
                 If true, the usage of the ECC bounds is skipped. This has the
                 effect that percentiles outside of the range given by the input