Option to cap low winds to 0.5 m/s

.zenodo.json

@@ -125,6 +125,10 @@
       "name": "Braun, Marco",
       "affiliation": "Ouranos Consortium, Montréal, Québec, Canada",
       "orcid": "0000-0001-5061-3217"
+    },
+    {
+      "name": "Castro, Dante",
+      "affiliation": "Helmholtz-Zentrum Hereon, Geesthacht, Germany"
     }
   ],
   "keywords": [

AUTHORS.rst

@@ -40,3 +40,4 @@ Contributors
 * Ag Stephens <[email protected]> `@agstephens <https://github.com/agstephens>`_
 * Maliko Tanguy <[email protected]> `@malngu <https://github.com/malngu>`_
 * Christopher Whelan `@qwhelan <https://github.com/qwhelan>`_
+* Dante Castro <[email protected]> `@profesorpaiche <https://github.com/profesorpaiche>`_

CHANGES.rst

@@ -4,7 +4,7 @@ Changelog
 
 v0.48 (unreleased)
 ------------------
-Contributors to this version: Juliette Lavoie (:user:`juliettelavoie`), Pascal Bourgault (:user:`aulemahal`), Trevor James Smith (:user:`Zeitsperre`), David Huard (:user:`huard`), Éric Dupuis (:user:`coxipi`).
+Contributors to this version: Juliette Lavoie (:user:`juliettelavoie`), Pascal Bourgault (:user:`aulemahal`), Trevor James Smith (:user:`Zeitsperre`), David Huard (:user:`huard`), Éric Dupuis (:user:`coxipi`), Dante Castro (:user:`profesorpaiche`).
 
 Announcements
 ^^^^^^^^^^^^^
@@ -21,6 +21,7 @@ New features and enhancements
 * Support ``indexer`` keyword in YAML indicator description. (:issue:`1522`, :pull:`1561`).
 * New ``xclim.core.calendar.stack_periods`` and ``unstack_periods`` for performing ``rolling(time=...).construct(..., stride=...)`` but with non-uniform temporal periods like years or months. They replace ``xclim.sdba.processing.construct_moving_yearly_window`` and ``unpack_moving_yearly_window`` which are deprecated and will be removed in a future release.
 * New ``as_dataset`` options for ``xclim.set_options``. When True, indicators will output Datasets instead of DataArrays. (:issue:`1257`, :pull:`1625`).
+* Added new option for UTCI calculation to cap low wind velocities to a minimum of 0.5 m/s following Bröde (2012) guidelines.
 
 Breaking changes
 ^^^^^^^^^^^^^^^^

xclim/indices/_conversion.py

@@ -1781,6 +1781,7 @@ def universal_thermal_climate_index(
     rlus: xr.DataArray | None = None,
     stat: str = "sunlit",
     mask_invalid: bool = True,
+    wind_cap_min: bool = False,
 ) -> xr.DataArray:
     r"""Universal thermal climate index (UTCI).
 
@@ -1818,6 +1819,9 @@ def universal_thermal_climate_index(
         If True (default), UTCI values are NaN where any of the inputs are outside
         their validity ranges : -50°C < tas < 50°C,  -30°C < tas - mrt < 30°C
         and  0.5 m/s < sfcWind < 17.0 m/s.
+    wind_cap_min: bool
+        If True, low wind velocities are capped to a minimum of 0.5 m/s. This ensures
+        UTCI calculation for low winds. Default value False.
 
     Returns
     -------
@@ -1842,6 +1846,8 @@ def universal_thermal_climate_index(
     e_sat = saturation_vapor_pressure(tas=tas, method="its90")
     tas = convert_units_to(tas, "degC")
     sfcWind = convert_units_to(sfcWind, "m/s")
+    if wind_cap_min:
+        sfcWind = sfcWind.clip(0.5, None)
     if mrt is None:
         mrt = mean_radiant_temperature(
             rsds=rsds, rsus=rsus, rlds=rlds, rlus=rlus, stat=stat
@@ -1868,7 +1874,7 @@ def universal_thermal_climate_index(
             & (tas < 50.0)
             & (-30 < delta)
             & (delta < 30)
-            & (0.5 < sfcWind)
+            & (0.5 <= sfcWind)
             & (sfcWind < 17.0)
         )
     return utci