update README

Author: Andy Barrett

notebooks/SMAP/README.md

@@ -2,10 +2,16 @@
 
 ### Summary
 
-In this set of three tutorials we demonstrate how to search for, download and plot SMAP data. Tutorial 1 demonstrates how to search for and download SMAP data using the `earthaccess` library. The second tutorial demonstrates how to read in and plot the data downloaded in Tutorial 1. And Tutorial 3 provides information on the surface quality and retrieval quality flags. 
+This set of three tutorials demonstrates how to search for, download and plot SMAP data using `xarray` and how to make the SMAP data into a georeferenced dataset. 
 
 We use the [SMAP L3 Radiometer Global Daily 36 km EASE-Grid Soil Moisture, Version 8](https://nsidc.org/data/SPL3SMP/versions/8) data set as an example.
 
+[working_with_smap_data_in_xarray](notebooks/SMAP/working_with_smap_in_xarray.ipynb) demonstrates how to search for and download SMAP data using `earthaccess`, and how to load a single group into an `xarray.Dataset` using `open_dataset`.  It also shows how to add informative dimension names and geospatial coordinates to the dataset so that the data variables can be plotted and analyzed using the powerful `xarray` methods.
+
+[working_with_smap_as_datatree](notebooks/SMAP/working_with_smap_as_datatree.ipynb) demonstrates how to load the full SMAP datafile as an `xarray.Datatree`.  It also shows how to load a time series of SMAP files.
+
+[create_geospatial_dataset_in_xarray](notebooks/SMAP/create_geospatial_dataset_in_xarray.ipynb) is essentially the same workflow as `working_with_smap_data_in_xarray` but provides more detail and the rationale behind the modifications.
+
 **NOTE** these notebooks are an updated version of the notebooks orginially published in this [repo](https://github.com/nsidc/smap_python_notebooks/tree/main). The notebooks are based on notebooks originally provided to NSIDC by Adam Purdy. Jennifer Roebuck of NSIDC applied the following updates:
 * Used `earthaccess` instead of `requests` for authentication, searching for and downloading the data. This reduced the code to just a few lines.
 * Used a more recent version of SPL3SMP (version 8).
@@ -21,5 +27,4 @@ To run the notebook provided in this folder, please see the [NSIDC-Data-Tutorial
 ### Key Learning Objectives
 
 1. Use the `earthaccess` library to search for and download SMAP data.
-2. Use the `h5py` library to read in the HDF5 files and plot the variables on a map using `cartopy` and `matplotlib`.
-3. Understand the surface quality and retrieval quality flag options.
+2. Use the `xarray` library to read in the HDF5 files and plot the variables on a map using `xarray` plotting methods and `cartopy`.