Changed default number of cascade levels to 6 everywhere in the project (#387)

* Changed default number of cascade levels to 6 everywhere in the project

* Ran black on sseps.py

* Added some documentation to why 6 is the default: referred to the issue on GitHub

Author: sidekock

examples/anvil_nowcast.py

@@ -99,7 +99,7 @@
     np.array([0.5]), metadata, threshold=0.1, zerovalue=-15.0
 )
 forecast_sprog = sprog.forecast(
-    rainrate_field_db[-3:], velocity, 3, n_cascade_levels=8, R_thr=rainrate_thr[0]
+    rainrate_field_db[-3:], velocity, 3, n_cascade_levels=6, R_thr=rainrate_thr[0]
 )
 forecast_sprog, _ = transformation.dB_transform(
     forecast_sprog, threshold=-10.0, inverse=True

pysteps/blending/clim.py

@@ -22,7 +22,7 @@
 import numpy as np
 
 
-def get_default_skill(n_cascade_levels=8, n_models=1):
+def get_default_skill(n_cascade_levels=6, n_models=1):
     """
     Get the default climatological skill values as given in :cite:`BPS2006`.
     Take subset of n_cascade_levels or add entries with small values (1e-4) if
@@ -31,7 +31,7 @@ def get_default_skill(n_cascade_levels=8, n_models=1):
     Parameters
     ----------
     n_cascade_levels: int, optional
-      Number of cascade levels. Defaults to 8.
+      Number of cascade levels. Defaults to 6, see issue #385 on GitHub.
     n_models: int, optional
       Number of NWP models. Defaults to 1.
 
@@ -157,7 +157,7 @@ def save_skill(
 
 def calc_clim_skill(
     outdir_path,
-    n_cascade_levels=8,
+    n_cascade_levels=6,
     n_models=1,
     window_length=30,
 ):
@@ -168,7 +168,7 @@ def calc_clim_skill(
     Parameters
     ----------
     n_cascade_levels: int, optional
-      Number of cascade levels.
+      Number of cascade levels. Defaults to 6, see issue #385 on GitHub.
     outdir_path: string
       Path to folder where the historical skill are stored. Defaults to
       path_workdir from rcparams.

pysteps/blending/steps.py

@@ -74,7 +74,7 @@ def forecast(
     timestep,
     issuetime,
     n_ens_members,
-    n_cascade_levels=8,
+    n_cascade_levels=6,
     blend_nwp_members=False,
     precip_thr=None,
     norain_thr=0.0,
@@ -153,8 +153,8 @@ def forecast(
       equal to or larger than the number of NWP ensemble members / number of
       NWP models.
     n_cascade_levels: int, optional
-      The number of cascade levels to use. Default set to 8 due to default
-      climatological skill values on 8 levels.
+      The number of cascade levels to use. Defaults to 6,
+      see issue #385 on GitHub.
     blend_nwp_members: bool
       Check if NWP models/members should be used individually, or if all of
       them are blended together per nowcast ensemble member. Standard set to

pysteps/nowcasts/anvil.py

@@ -39,7 +39,7 @@ def forecast(
     velocity,
     timesteps,
     rainrate=None,
-    n_cascade_levels=8,
+    n_cascade_levels=6,
     extrap_method="semilagrangian",
     ar_order=2,
     ar_window_radius=50,
@@ -86,7 +86,8 @@ def forecast(
         field. If set to None, no R(VIL) conversion is done and the outputs
         are in the same units as the inputs.
     n_cascade_levels: int, optional
-        The number of cascade levels to use.
+        The number of cascade levels to use. Defaults to 6, see issue #385
+        on GitHub.
     extrap_method: str, optional
         Name of the extrapolation method to use. See the documentation of
         pysteps.extrapolation.interface.

pysteps/nowcasts/sprog.py

@@ -71,7 +71,8 @@ def forecast(
     precip_thr: float, required
         The threshold value for minimum observable precipitation intensity.
     n_cascade_levels: int, optional
-        The number of cascade levels to use.
+        The number of cascade levels to use. Defaults to 6, see issue #385
+        on GitHub.
     extrap_method: str, optional
         Name of the extrapolation method to use. See the documentation of
         pysteps.extrapolation.interface.

pysteps/nowcasts/sseps.py

@@ -104,7 +104,8 @@ def forecast(
     n_ens_members: int
         The number of ensemble members to generate.
     n_cascade_levels: int
-        The number of cascade levels to use.
+        The number of cascade levels to use. Defaults to 6, see issue #385
+         on GitHub.
     extrap_method: {'semilagrangian'}
         Name of the extrapolation method to use. See the documentation of
         pysteps.extrapolation.interface.

pysteps/nowcasts/steps.py

@@ -87,7 +87,8 @@ def forecast(
     n_ens_members: int, optional
         The number of ensemble members to generate.
     n_cascade_levels: int, optional
-        The number of cascade levels to use.
+        The number of cascade levels to use. Defaults to 6, see issue #385
+         on GitHub.
     precip_thr: float, optional
         Specifies the threshold value for minimum observable precipitation
         intensity. Required if mask_method is not None or conditional is True.