add model reader for gocart output

monetio/models/__init__.py

@@ -8,6 +8,7 @@
     camx,
     cmaq,
     fv3chem,
+    gocart,
     hysplit,
     hytraj,
     icap_mme,
@@ -27,6 +28,7 @@
     "cmaq",
     "camx",
     "fv3chem",
+    "gocart",
     "hysplit",
     "hytraj",
     "icap_mme",

monetio/models/gocart.py

@@ -0,0 +1,78 @@
+""" GOCART File Reader """
+
+import xarray as xr
+
+
+def open_mfdataset(fnames):
+    """Method to open GOCART netcdf files.
+
+    Parameters
+    ----------
+    fname : string or list
+        fname is the path to the file or files.  It will accept hot keys in
+        strings as well.
+
+    Returns
+    -------
+    xarray.DataSet
+        GOCART model dataset in standard format for use in MELODIES-MONET
+
+    """
+
+    # open the dataset using xarray
+    ds = xr.open_mfdataset(
+        fnames,
+        concat_dim="time",
+        combine="nested",
+        drop_variables=["AOD_BC", "AOD_DU", "AOD_OC", "AOD_SS", "AOD_SU"],
+    )
+
+    ds["AOD470"] = ds.AOD.isel(lev=0)
+    ds["AOD550"] = ds.AOD.isel(lev=1)
+    ds["AOD670"] = ds.AOD.isel(lev=2)
+    ds["AOD870"] = ds.AOD.isel(lev=3)
+    ds = ds.drop_vars("AOD").drop_dims("lev")
+
+    ds = _fix(ds)
+
+    return ds
+
+
+def _fix(ds):
+    ds = _fix_grid(ds)
+
+    ds = ds.expand_dims("z")
+    ds = ds.transpose("time", "z", "y", "x")
+
+    return ds
+
+
+def _fix_grid(ds):
+    from numpy import meshgrid
+
+    # Create 2-D lat/lon grid with dims ('y', 'x') and lon in [-180, 180)
+    lat = ds.lat.values
+    lon = ds.lon.values
+    lon, lat = meshgrid(lon, lat)
+    ds = ds.rename_dims({"lat": "y", "lon": "x"}).drop_vars(["lat", "lon"])
+    ds["longitude"] = (
+        ("y", "x"),
+        lon,
+        {
+            "long_name": "Longitude",
+            "units": "degree_east",
+            "standard_name": "longitude",
+        },
+    )
+    ds["latitude"] = (
+        ("y", "x"),
+        lat,
+        {
+            "long_name": "Latitude",
+            "units": "degree_north",
+            "standard_name": "latitude",
+        },
+    )
+    ds = ds.reset_coords().set_coords(["time", "latitude", "longitude"])
+    del lon, lat
+    return ds