MODIS L2 reader update

monetio/sat/_modis_l2_mm.py

@@ -1,6 +1,7 @@
 import logging
 import sys
 from collections import OrderedDict
+from datetime import datetime, timezone
 from glob import glob
 
 import numpy as np
@@ -20,18 +21,23 @@ def read_dataset(fname, variable_dict):
     """
     from monetio.sat.hdfio import hdf_close, hdf_list, hdf_open, hdf_read
 
+    epoch_1993 = int(datetime(1993, 1, 1, tzinfo=timezone.utc).timestamp())
+
     print("reading " + fname)
 
     ds = xr.Dataset()
 
     f = hdf_open(fname)
     hdf_list(f)
-    latitude = hdf_read(f, "Latitude")  # noqa: F841
-    longitude = hdf_read(f, "Longitude")  # noqa: F841
-    start_time = hdf_read(f, "Scan_Start_Time")  # noqa: F841
+    # Geolocation and Time Parameters
+    latitude = hdf_read(f, "Latitude")
+    longitude = hdf_read(f, "Longitude")
+    # convert seconds since 1993 to since 1970
+    start_time = hdf_read(f, "Scan_Start_Time") + epoch_1993
     for varname in variable_dict:
         print(varname)
         values = hdf_read(f, varname)
+        print("min, max: ", values.min(), " ", values.max())
         if "scale" in variable_dict[varname]:
             values = variable_dict[varname]["scale"] * values
         if "minimum" in variable_dict[varname]:
@@ -46,6 +52,15 @@ def read_dataset(fname, variable_dict):
             ds.attrs["quality_thresh"] = variable_dict[varname]["quality_flag"]
     hdf_close(f)
 
+    ds = ds.assign_coords(
+        {
+            "lon": (["dim_0", "dim_1"], longitude),
+            "lat": (["dim_0", "dim_1"], latitude),
+            "time": (["dim_0", "dim_1"], start_time),
+        }
+    )
+    ds = ds.rename_dims({"dim_0": "Cell_Along_Swath", "dim_1": "Cell_Across_Swath"})
+
     return ds
 
 
@@ -81,7 +96,10 @@ def read_mfdataset(fnames, variable_dict, debug=False):
         logging_level = logging.DEBUG
         logging.basicConfig(stream=sys.stdout, level=logging_level)
 
-    files = sorted(glob(fnames))
+    if isinstance(fnames, str):
+        files = sorted(glob(fnames))
+    else:
+        files = fnames
 
     granules = OrderedDict()