TC track forecast missing time period handling (#91)

* continue reading messages from a multimessage file in case a track is missing timeperiods
* Apply suggestions from code review
* Update CHANGELOG.md

---------

Co-authored-by: Thomas Roosli <thomas.roeoesli@meteoswiss.ch>
Co-authored-by: Lukas Riedel <34276446+peanutfun@users.noreply.github.com>

Author: 3 people

CHANGELOG.md

@@ -16,6 +16,8 @@ Code freeze date: YYYY-MM-DD
 
 ### Fixed
 
+- `TCForecast` now skips "untrackable" TCs when reading multi-message `.bufr` files [#91](https://github.com/CLIMADA-project/climada_petals/pull/91)
+
 ### Deprecated
 
 ### Removed

climada_petals/hazard/tc_tracks_forecast.py

@@ -277,7 +277,7 @@ def read_one_bufr_tc(self, file, id_no=None):
                 n_timestep = ec.codes_get_size(bufr, 'timePeriod') + 1
             except ec.CodesInternalError:
                 LOGGER.warning("Track %s has no defined timePeriod. Track is discarded.", sid)
-                return None
+                continue
 
             # get number of ensemble members
             ens_no = ec.codes_get_array(bufr, "ensembleMemberNumber")

climada_petals/hazard/test/data/test202308220000.bufr

@@ -38,6 +38,11 @@
 https://confluence.ecmwf.int/display/FCST/New+Tropical+Cyclone+Wind+Radii+product
 """
 
+TEST_BUFR_FILE_MULTIMESSAGE_MISSING_TIMEPERIOD = DATA_DIR.joinpath('test202308220000.bufr')
+"""TC tracks in four BUFR formats as provided by ECMWF. Sourced from
+https://confluence.ecmwf.int/display/FCST/New+Tropical+Cyclone+Wind+Radii+product
+"""
+
 TEST_CXML_FILE = DATA_DIR.joinpath("cxml_sample_track.xml")
 """A sample CXML file holding forecast data, subset from the ECMWF archive at
 https://confluence.ecmwf.int/display/TIGGE/Tools#Tools-ECMWFTropicalCycloneTrackData(XMLformat)
@@ -80,7 +85,6 @@ def test_fetch_ecmwf(self):
                          np.datetime64('2020-03-19T12:00:00.000000'))
         self.assertEqual(forecast.data[1].is_ensemble, True)
 
-
     def test_ecmwf_multimessage(self):
         """Test ECMWF reader in multimessage format"""
         forecast = TCForecast()
@@ -100,6 +104,22 @@ def test_ecmwf_multimessage(self):
             np.array(['70E', '70W', '71E', '71W', '72W'], dtype=str)
             )
 
+    def test_ecmwf_multimessage_missing_timeperiod(self):
+        """Test ECMWF reader should continue reading messages if one track misses timePeriod"""
+        with self.assertLogs('climada_petals.hazard.tc_tracks_forecast', level='INFO') as cm:
+            forecast = TCForecast()
+            forecast.fetch_ecmwf(files=TEST_BUFR_FILE_MULTIMESSAGE_MISSING_TIMEPERIOD)
+        self.assertIn(
+            "Track 07L has no defined timePeriod. Track is discarded.", cm.output[0]
+        )
+        self.assertEqual(forecast.size, 125)
+        np.testing.assert_array_equal(
+            np.unique(
+                [forecast.data[ind_i].name
+                 for ind_i in np.arange(122)]
+            ),
+            np.array(['09L', 'FRANKLIN', 'GERT'], dtype=str)
+        )
 
     def test_equal_timestep(self):
         """Test equal timestep"""