add water cycle intensity indices and indicators

xclim/data/fr.json

@@ -1403,5 +1403,11 @@
     "abstract": "Les unités de froid (chill units) sont une mesure du potentiel de débourrement de différentes récoltes basée sur le modèle Utah.",
     "long_name": "Unités de froid selon le modèle Utah",
     "description": "Les unités de froid (chill units) sont une mesure du potentiel de débourrement de différentes récoltes basée sur le modèle Utah."
+  },
+  "WATER_CYCLE_INTENSITY": {
+    "title": "Intensité du cycle de l'eau",
+    "long_name": "Intensité du cycle de l'eau",
+    "description": "Indice {freq} de l'intensité du cycle de l'eau, défini comme la somme de la précipitation et de l'évapotranspiration.",
+    "abstract": "la somme de la précipitation et de l'évapotranspiration."
   }
 }

xclim/data/variables.yml

@@ -16,6 +16,12 @@ variables:
     cell_methods: "time: mean"
     description: The amount of water, in all phases, flowing in the river channel and flood plain.
     standard_name: water_volume_transport_in_river_channel
+  evspsbl:
+    canonical_units: kg m-2 s-1
+    cell_methods: "time: mean"
+    description: Actual evapotranspiration flux.
+    dimensions: "[discharge]"
+    standard_name: water_evapotranspiration_flux
   evspsblpot:
     canonical_units: kg m-2 s-1
     cell_methods: "time: mean"

xclim/indicators/atmos/_precip.py

@@ -57,6 +57,7 @@
     "standardized_precipitation_index",
     "warm_and_dry_days",
     "warm_and_wet_days",
+    "water_cycle_intensity",
     "wet_precip_accumulation",
     "wet_spell_frequency",
     "wet_spell_max_length",
@@ -790,7 +791,19 @@ class HrPrecip(Hourly):
     units=["", "", "days"],
     abstract="Start time, end time and length of the rain season, notably useful for West Africa (sivakumar, 1998). "
     "The rain season starts with a period of abundant rainfall, followed by a period without prolonged dry sequences, "
-    "which must happen before a given date. The rain season stops during a dry period happening after a given date",
+    "which must happen before a given date. The rain season stops during a dry period happening after a given date.",
     cell_methods="",
     compute=indices.rain_season,
 )
+
+water_cycle_intensity = PrecipWithIndexing(
+    title="Water cycle intensity",
+    identifier="water_cycle_intensity",
+    realm="atmos",
+    units="mm",
+    long_name="Water cycle intensity",
+    description="The {freq} water cycle intensity, defined as the sum of precipitation and actual evapotranspiration.",
+    abstract="The sum of precipitation and actual evapotranspiration.",
+    cell_methods="time: sum over days",
+    compute=indices.water_cycle_intensity,
+)

xclim/indices/_multivariate.py

@@ -58,6 +58,7 @@
     "warm_and_dry_days",
     "warm_and_wet_days",
     "warm_spell_duration_index",
+    "water_cycle_intensity",
     "winter_rain_ratio",
 ]
 
@@ -1865,3 +1866,36 @@ def blowing_snow(
     out = cond.resample(time=freq).sum(dim="time")
     out = out.assign_attrs(units=to_agg_units(out, snd, "count"))
     return out
+
+
+@declare_units(pr="[precipitation]", evspsbl="[precipitation]")
+def water_cycle_intensity(
+    pr: xarray.DataArray, evspsbl: xarray.DataArray, freq="YS"
+) -> xarray.DataArray:
+    """Water cycle intensity.
+
+    The sum of precipitation and actual evapotranspiration.
+
+    Parameters
+    ----------
+    pr : xarray.DataArray
+        Precipitation flux.
+    evspsbl : xarray.DataArray
+        Actual evapotranspiration flux.
+
+    Returns
+    -------
+    xarray.DataArray
+        The sum of precipitation and actual evapotranspiration for each period.
+
+    References
+    ----------
+    :cite:cts:`huntington_2018`
+    """
+    pr = convert_units_to(pr, evspsbl)
+
+    # Water cycle intensity
+    wci = pr + evspsbl
+    wci = rate2amount(wci)
+    wci = wci.resample(time=freq).sum(dim="time").assign_attrs(units=wci.units)
+    return wci