Updating tutorials to use fieldset.constants dictionary

Author: erikvansebille

docs/user_guide/examples/tutorial_Argofloats.ipynb

@@ -131,7 +131,7 @@
     "# Convert to SGRID-compliant dataset and create FieldSet\n",
     "ds_fset = parcels.convert.copernicusmarine_to_sgrid(fields=fields)\n",
     "fieldset = parcels.FieldSet.from_sgrid_conventions(ds_fset)\n",
-    "fieldset.add_constant(\"mindepth\", 1.0)\n",
+    "fieldset.constants[\"mindepth\"] = 1.0\n",
     "\n",
     "# Define a new Particle type including extra Variables\n",
     "ArgoParticle = parcels.Particle.add_variable(\n",

docs/user_guide/examples/tutorial_croco_3D.ipynb

@@ -91,7 +91,7 @@
     "fieldset = parcels.FieldSet.from_sgrid_conventions(ds_fset)\n",
     "\n",
     "# Add the critical depth (`hc`) as a constant to the fieldset\n",
-    "fieldset.add_constant(\"hc\", ds_fields.hc.item())"
+    "fieldset.constants[\"hc\"] = ds_fields.hc.item()"
    ]
   },
   {
@@ -204,7 +204,7 @@
    "source": [
     "fieldset_noW = parcels.FieldSet.from_sgrid_conventions(ds_fset)\n",
     "fieldset_noW.W.data[:] = 0.0\n",
-    "fieldset_noW.add_constant(\"hc\", ds_fields.hc.item())\n",
+    "fieldset_noW.constants[\"hc\"] = ds_fields.hc.item()\n",
     "\n",
     "X, Z = np.meshgrid(\n",
     "    [40e3, 80e3, 120e3],\n",

docs/user_guide/examples/tutorial_diffusion.ipynb

@@ -90,7 +90,7 @@
     "\n",
     "Just like velocities, diffusivities are passed to Parcels in the form of `Field` objects. When using `DiffusionUniformKh`, they should be added to the `FieldSet` object as constant fields, e.g. `fieldset.add_constant_field(\"Kh_zonal\", 1, mesh=\"flat\")`.\n",
     "\n",
-    "To make a central difference approximation for computing the gradient in diffusivity, a resolution for this approximation `dres` is needed: _Parcels_ approximates the gradients in diffusivities by using their values at the particle's location ± `dres` (in both $x$ and $y$). A value of `dres` must be specified and added to the FieldSet by the user (e.g. `fieldset.add_constant(\"dres\", 0.01)`). Currently, it is unclear what the best value of `dres` is. From experience, the size of `dres` should be smaller than the spatial resolution of the data, but within reasonable limits of machine precision to avoid numerical errors. We are working on a method to compute gradients differently so that specifying `dres` is not necessary anymore.\n",
+    "To make a central difference approximation for computing the gradient in diffusivity, a resolution for this approximation `dres` is needed: _Parcels_ approximates the gradients in diffusivities by using their values at the particle's location ± `dres` (in both $x$ and $y$). A value of `dres` must be specified and added to the FieldSet by the user (e.g. `fieldset.constants[\"dres\"] = 0.01`). Currently, it is unclear what the best value of `dres` is. From experience, the size of `dres` should be smaller than the spatial resolution of the data, but within reasonable limits of machine precision to avoid numerical errors. We are working on a method to compute gradients differently so that specifying `dres` is not necessary anymore.\n",
     "\n",
     "## Example: Impermeable Diffusivity Profile\n",
     "\n",
@@ -206,7 +206,7 @@
    "source": [
     "fieldset = parcels.FieldSet.from_sgrid_conventions(ds, mesh=\"flat\")\n",
     "fieldset.add_constant_field(\"Kh_zonal\", 1, mesh=\"flat\")\n",
-    "fieldset.add_constant(\"dres\", 0.00005)"
+    "fieldset.constants[\"dres\"] = 0.00005"
    ]
   },
   {
@@ -537,7 +537,7 @@
     ")\n",
     "fieldset.add_field(cell_areas_field)\n",
     "\n",
-    "fieldset.add_constant(\"Cs\", 0.1)"
+    "fieldset.constants[\"Cs\"] = 0.1"
    ]
   },
   {