add xarray info

book/tutorials/NASA-Earthdata-Cloud-Access/3. earthaccess.ipynb

@@ -60,13 +60,15 @@
     "\n",
     "The tutorial uses `python` and requires the following packages:\n",
     "- `earthaccess`, which enables Earthdata Login authentication and retrieves AWS credentials; enables collection and granule searches; and S3 access;\n",
-    "- `xarray`, used to load data;\n",
+    "- `xarray`, used to load N-dimensional data with labeled axes;\n",
     "- `hvplot`, used to visualize land ice height data.\n",
     "\n",
     "We are going to import the whole `earthaccess` package.\n",
     "\n",
     "We will also import the whole `xarray` package but use a standard short name `xr`, using the `import <package> as <short_name>` syntax.  We could use anything for a short name but `xr` is an accepted standard that most `xarray` users are familiar with.\n",
     "\n",
+    "[`xarray`](https://docs.xarray.dev/en/stable/) is a powerful library for working with multi-dimensional data using labeled indices (analogous to Pandas for tabular data). A few great tutorials for learning Xarray are [here](https://nasa-openscapes.github.io/2021-Cloud-Hackathon/tutorials/03_Xarray.html) and [here](https://tutorial.xarray.dev/intro.html).\n",
+    "\n",
     "We only need the `xarray` module from `hvplot` so we import that using the `import <package>.<module>` syntax."
    ]
   },