diff --git a/docs/source/how-tos/source/mars.ipynb b/docs/source/how-tos/source/mars.ipynb
index 7d551d53d..caf59849e 100644
--- a/docs/source/how-tos/source/mars.ipynb
+++ b/docs/source/how-tos/source/mars.ipynb
@@ -1,199 +1,205 @@
 {
-    "cells": [
-        {
-            "cell_type": "markdown",
-            "id": "f7049550-e9a9-4706-82e6-f0fe7892c88b",
-            "metadata": {
-                "editable": true,
-                "slideshow": {
-                    "slide_type": ""
-                },
-                "tags": []
-            },
-            "source": [
-                "# Retrieving data from the ECMWF MARS archive"
-            ]
-        },
-        {
-            "cell_type": "raw",
-            "id": "81fbdd95-ca93-4f00-8423-57b419d030d9",
-            "metadata": {
-                "editable": true,
-                "raw_mimetype": "text/restructuredtext",
-                "slideshow": {
-                    "slide_type": ""
-                },
-                "tags": []
-            },
-            "source": [
-                "The :ref:`ecmwf-open-data <data-sources-mars>` source provides access to the ECMWF MARS archive."
-            ]
-        },
-        {
-            "cell_type": "code",
-            "execution_count": 1,
-            "id": "2a355c97-8f45-42a2-a0a5-c3390a0aba22",
-            "metadata": {},
-            "outputs": [
-                {
-                    "data": {
-                        "text/html": [
-                            "<style type=\"text/css\">table.ek td {\n",
-                            "    vertical-align: top;\n",
-                            "    text-align: left !important;\n",
-                            "}\n",
-                            "\n",
-                            "table.ek th {\n",
-                            "    vertical-align: top;\n",
-                            "    text-align: left !important;\n",
-                            "}\n",
-                            "</style><div class=\"eh-description\">GRIB file</div><hr>\n",
-                            "<table class=\"eh-table\">\n",
-                            "<tr><td><b>path</b></td><td>/var/folders/93/w0p869rx17q98wxk83gn9ys40000gn/T/earthkit-data-cgr/mars-retriever-800da46cbbfad84aa69886ae989816d43a8f31e9510aec55c269ba56b10f6c77.cache</td></tr> <tr><td><b>size</b></td><td>480</td></tr> <tr><td><b>types</b></td><td>fieldlist, pandas, xarray, numpy, array</td></tr>\n",
-                            "</table>"
-                        ],
-                        "text/plain": [
-                            "GribData(path=/var/folders/93/w0p869rx17q98wxk83gn9ys40000gn/T/earthkit-data-cgr/mars-retriever-800da46cbbfad84aa69886ae989816d43a8f31e9510aec55c269ba56b10f6c77.cache)"
-                        ]
-                    },
-                    "execution_count": 1,
-                    "metadata": {},
-                    "output_type": "execute_result"
-                }
-            ],
-            "source": [
-                "import earthkit.data as ekd\n",
-                "\n",
-                "d = ekd.from_source(\n",
-                "    \"mars\",\n",
-                "    request=dict(\n",
-                "        param=[\"2t\", \"msl\"],\n",
-                "        levtype=\"sfc\",\n",
-                "        area=[50, -10, 40, 10],\n",
-                "        grid=[2, 2],\n",
-                "        date=\"2023-05-10\",  # N,W,S,E\n",
-                "    ),\n",
-                ")\n",
-                "d"
-            ]
-        },
-        {
-            "cell_type": "code",
-            "execution_count": 2,
-            "id": "33b29363-1e94-4ae8-860d-714d3b6b023f",
-            "metadata": {},
-            "outputs": [
-                {
-                    "data": {
-                        "text/html": [
-                            "<div>\n",
-                            "<style scoped>\n",
-                            "    .dataframe tbody tr th:only-of-type {\n",
-                            "        vertical-align: middle;\n",
-                            "    }\n",
-                            "\n",
-                            "    .dataframe tbody tr th {\n",
-                            "        vertical-align: top;\n",
-                            "    }\n",
-                            "\n",
-                            "    .dataframe thead th {\n",
-                            "        text-align: right;\n",
-                            "    }\n",
-                            "</style>\n",
-                            "<table border=\"1\" class=\"dataframe\">\n",
-                            "  <thead>\n",
-                            "    <tr style=\"text-align: right;\">\n",
-                            "      <th></th>\n",
-                            "      <th>parameter.variable</th>\n",
-                            "      <th>time.valid_datetime</th>\n",
-                            "      <th>time.base_datetime</th>\n",
-                            "      <th>time.step</th>\n",
-                            "      <th>vertical.level</th>\n",
-                            "      <th>vertical.level_type</th>\n",
-                            "      <th>ensemble.member</th>\n",
-                            "      <th>geography.grid_type</th>\n",
-                            "    </tr>\n",
-                            "  </thead>\n",
-                            "  <tbody>\n",
-                            "    <tr>\n",
-                            "      <th>0</th>\n",
-                            "      <td>2t</td>\n",
-                            "      <td>2023-05-10 12:00:00</td>\n",
-                            "      <td>2023-05-10 12:00:00</td>\n",
-                            "      <td>0 days</td>\n",
-                            "      <td>0</td>\n",
-                            "      <td>surface</td>\n",
-                            "      <td>0</td>\n",
-                            "      <td>regular_ll</td>\n",
-                            "    </tr>\n",
-                            "    <tr>\n",
-                            "      <th>1</th>\n",
-                            "      <td>msl</td>\n",
-                            "      <td>2023-05-10 12:00:00</td>\n",
-                            "      <td>2023-05-10 12:00:00</td>\n",
-                            "      <td>0 days</td>\n",
-                            "      <td>0</td>\n",
-                            "      <td>surface</td>\n",
-                            "      <td>0</td>\n",
-                            "      <td>regular_ll</td>\n",
-                            "    </tr>\n",
-                            "  </tbody>\n",
-                            "</table>\n",
-                            "</div>"
-                        ],
-                        "text/plain": [
-                            "  parameter.variable time.valid_datetime  time.base_datetime time.step  \\\n",
-                            "0                 2t 2023-05-10 12:00:00 2023-05-10 12:00:00    0 days   \n",
-                            "1                msl 2023-05-10 12:00:00 2023-05-10 12:00:00    0 days   \n",
-                            "\n",
-                            "   vertical.level vertical.level_type ensemble.member geography.grid_type  \n",
-                            "0               0             surface               0          regular_ll  \n",
-                            "1               0             surface               0          regular_ll  "
-                        ]
-                    },
-                    "execution_count": 2,
-                    "metadata": {},
-                    "output_type": "execute_result"
-                }
-            ],
-            "source": [
-                "d.to_fieldlist().ls()"
-            ]
-        },
-        {
-            "cell_type": "code",
-            "execution_count": null,
-            "id": "8db01079-ae66-41cb-941f-0b03dda7d46f",
-            "metadata": {
-                "editable": true,
-                "slideshow": {
-                    "slide_type": ""
-                },
-                "tags": []
-            },
-            "outputs": [],
-            "source": []
-        }
-    ],
-    "metadata": {
-        "kernelspec": {
-            "display_name": "dev",
-            "language": "python",
-            "name": "dev"
-        },
-        "language_info": {
-            "codemirror_mode": {
-                "name": "ipython",
-                "version": 3
-            },
-            "file_extension": ".py",
-            "mimetype": "text/x-python",
-            "name": "python",
-            "nbconvert_exporter": "python",
-            "pygments_lexer": "ipython3",
-            "version": "3.13.1"
-        }
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "f7049550-e9a9-4706-82e6-f0fe7892c88b",
+   "metadata": {
+    "editable": true,
+    "slideshow": {
+     "slide_type": ""
     },
-    "nbformat": 4,
-    "nbformat_minor": 5
+    "tags": []
+   },
+   "source": [
+    "# Retrieving data from the ECMWF MARS archive"
+   ]
+  },
+  {
+   "cell_type": "raw",
+   "id": "81fbdd95-ca93-4f00-8423-57b419d030d9",
+   "metadata": {
+    "editable": true,
+    "raw_mimetype": "text/restructuredtext",
+    "slideshow": {
+     "slide_type": ""
+    },
+    "tags": []
+   },
+   "source": [
+    "The :ref:`mars <data-sources-mars>` source provides access to the ECMWF MARS archive."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "id": "2a355c97-8f45-42a2-a0a5-c3390a0aba22",
+   "metadata": {
+    "editable": true,
+    "slideshow": {
+     "slide_type": ""
+    },
+    "tags": []
+   },
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<style type=\"text/css\">table.ek td {\n",
+       "    vertical-align: top;\n",
+       "    text-align: left !important;\n",
+       "}\n",
+       "\n",
+       "table.ek th {\n",
+       "    vertical-align: top;\n",
+       "    text-align: left !important;\n",
+       "}\n",
+       "</style><div class=\"eh-description\">GRIB file</div><hr>\n",
+       "<table class=\"eh-table\">\n",
+       "<tr><td><b>path</b></td><td>/var/folders/93/w0p869rx17q98wxk83gn9ys40000gn/T/earthkit-data-cgr/mars-retriever-800da46cbbfad84aa69886ae989816d43a8f31e9510aec55c269ba56b10f6c77.cache</td></tr> <tr><td><b>size</b></td><td>480</td></tr> <tr><td><b>types</b></td><td>fieldlist, pandas, xarray, numpy, array</td></tr>\n",
+       "</table>"
+      ],
+      "text/plain": [
+       "GribData(path=/var/folders/93/w0p869rx17q98wxk83gn9ys40000gn/T/earthkit-data-cgr/mars-retriever-800da46cbbfad84aa69886ae989816d43a8f31e9510aec55c269ba56b10f6c77.cache)"
+      ]
+     },
+     "execution_count": 1,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "import earthkit.data as ekd\n",
+    "\n",
+    "d = ekd.from_source(\n",
+    "    \"mars\",\n",
+    "    request=dict(\n",
+    "        param=[\"2t\", \"msl\"],\n",
+    "        levtype=\"sfc\",\n",
+    "        area=[50, -10, 40, 10],\n",
+    "        grid=[2, 2],\n",
+    "        date=\"2023-05-10\",  # N,W,S,E\n",
+    "    ),\n",
+    ")\n",
+    "d"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "id": "33b29363-1e94-4ae8-860d-714d3b6b023f",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style scoped>\n",
+       "    .dataframe tbody tr th:only-of-type {\n",
+       "        vertical-align: middle;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>parameter.variable</th>\n",
+       "      <th>time.valid_datetime</th>\n",
+       "      <th>time.base_datetime</th>\n",
+       "      <th>time.step</th>\n",
+       "      <th>vertical.level</th>\n",
+       "      <th>vertical.level_type</th>\n",
+       "      <th>ensemble.member</th>\n",
+       "      <th>geography.grid_type</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>0</th>\n",
+       "      <td>2t</td>\n",
+       "      <td>2023-05-10 12:00:00</td>\n",
+       "      <td>2023-05-10 12:00:00</td>\n",
+       "      <td>0 days</td>\n",
+       "      <td>0</td>\n",
+       "      <td>surface</td>\n",
+       "      <td>0</td>\n",
+       "      <td>regular_ll</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>1</th>\n",
+       "      <td>msl</td>\n",
+       "      <td>2023-05-10 12:00:00</td>\n",
+       "      <td>2023-05-10 12:00:00</td>\n",
+       "      <td>0 days</td>\n",
+       "      <td>0</td>\n",
+       "      <td>surface</td>\n",
+       "      <td>0</td>\n",
+       "      <td>regular_ll</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "  parameter.variable time.valid_datetime  time.base_datetime time.step  \\\n",
+       "0                 2t 2023-05-10 12:00:00 2023-05-10 12:00:00    0 days   \n",
+       "1                msl 2023-05-10 12:00:00 2023-05-10 12:00:00    0 days   \n",
+       "\n",
+       "   vertical.level vertical.level_type ensemble.member geography.grid_type  \n",
+       "0               0             surface               0          regular_ll  \n",
+       "1               0             surface               0          regular_ll  "
+      ]
+     },
+     "execution_count": 2,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "d.to_fieldlist().ls()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "8db01079-ae66-41cb-941f-0b03dda7d46f",
+   "metadata": {
+    "editable": true,
+    "slideshow": {
+     "slide_type": ""
+    },
+    "tags": []
+   },
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "dev",
+   "language": "python",
+   "name": "dev"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.13.1"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
 }