Merge pull request #1577 from OceanParcels/tutorial_note_particle_sampling

Note in the Parcels structure tutorial on the `field[particle]` sampling speed

Author: erikvansebille

docs/examples/tutorial_jit_vs_scipy.ipynb

@@ -5,7 +5,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# JIT Particles and Scipy particles\n"
+    "# JIT-vs-Scipy Particles"
    ]
   },
   {

docs/examples/tutorial_parcels_structure.ipynb

@@ -302,7 +302,7 @@
     "    ```python\n",
     "    value = fieldset.U[time, particle.depth, particle.lat, particle.lon]\n",
     "    ```\n",
-    "    or simple\n",
+    "    or simply\n",
     "    ```python\n",
     "    value = fieldset.U[particle]\n",
     "    ```\n",
@@ -321,7 +321,14 @@
     "  \n",
     "  - It is advised _not_ to update the particle location (`particle.lon`, `particle.lat`, `particle.depth`, and/or `particle.time`) directly, as that can negatively interfere with the way that particle movements by different kernels are vectorially added. Use `particle_dlon`, `particle_dlat`, `particle_ddepth`, and/or `particle_dtime` instead. See also the [kernel loop tutorial](https://docs.oceanparcels.org/en/latest/examples/tutorial_kernelloop.html).\n",
     "  \n",
-    "  - Note that one has to be careful with writing kernels for vector fields on Curvilinear grids. While Parcels automatically rotates the U and V field when necessary, this is not the case for for example wind data. In that case, a custom rotation function will have to be written.\n"
+    "  - Note that one has to be careful with writing kernels for vector fields on Curvilinear grids. While Parcels automatically rotates the U and V field when necessary, this is not the case for for example wind data. In that case, a custom rotation function will have to be written.\n",
+    "\n",
+    "  <div class=\"alert alert-info\">\n",
+    "  A note on Field interpoaltion notation\n",
+    "\n",
+    "  Note that for the interpolation of a `Field`, the second option (`value = fieldset.U[particle]`) is not only a short-hand notation for the (`value = fieldset.U[time, particle.depth, particle.lat, particle.lon]`); it is actually a _faster_ way to interpolate the field at the particle location in Scipy mode, as described in [this section of the JIT-vs-Scipy tutorial](https://docs.oceanparcels.org/en/latest/examples/tutorial_jit_vs_scipy.html#Further-digging-into-Scipy-mode:-adding-particle-keyword-to-Field-sampling).\n",
+    "  \n",
+    "  </div>"
    ]
   },
   {