Cif 286 cams

city_metrix/layers/__init__.py

@@ -21,3 +21,4 @@
 from .nasa_dem import NasaDEM
 from .era_5_hottest_day import Era5HottestDay
 from .impervious_surface import ImperviousSurface
+from .cams import Cams

city_metrix/layers/cams.py

@@ -0,0 +1,93 @@
+import cdsapi
+import os
+import xarray as xr
+import zipfile
+
+from .layer import Layer
+
+
+class Cams(Layer):
+    def __init__(self, start_date="2023-01-01", end_date="2023-12-31", **kwargs):
+        super().__init__(**kwargs)
+        self.start_date = start_date
+        self.end_date = end_date
+
+    def get_data(self, bbox):
+        min_lon, min_lat, max_lon, max_lat = bbox
+
+        c = cdsapi.Client()
+        c.retrieve(
+            'cams-global-reanalysis-eac4',
+            {
+                'variable': [
+                    "2m_temperature", "mean_sea_level_pressure",
+                    "particulate_matter_2.5um", "particulate_matter_10um",
+                    "carbon_monoxide", "nitrogen_dioxide", "ozone", "sulphur_dioxide"
+                ],
+                "model_level": ["60"],
+                "date": [f"{self.start_date}/{self.end_date}"],
+                'time': ['00:00', '03:00', '06:00', '09:00', '12:00', '15:00', '18:00', '21:00'],
+                'area': [max_lat, min_lon, min_lat, max_lon],
+                'data_format': 'netcdf_zip',
+            },
+            'cams_download.zip')
+
+        # If data files from earlier runs not deleted, save new files with postpended numbers
+        existing_cams_downloads = [fname for fname in os.listdir('.') if fname[:13] == 'cams_download' and fname[-3:] != 'zip']
+        num_id = len(existing_cams_downloads)
+        while f'cams_download_{num_id}' in existing_cams_downloads:
+            num_id += 1
+        fname = 'cams_download{0}'.format(['', '_{0}'.format(num_id)][int(num_id > 0)])
+        os.makedirs(fname, exist_ok=True)
+
+        # extract the ZIP file
+        with zipfile.ZipFile('cams_download.zip', 'r') as zip_ref:
+            # Extract all the contents of the ZIP file to the specified directory
+            zip_ref.extractall(fname)
+
+        # load netcdf files
+        dataarray_list = []
+        for nc_file in os.listdir(fname):
+            dataarray = xr.open_dataset(f'{fname}/{nc_file}')
+            dataarray_list.append(dataarray)
+
+        # not all variables have 'model_level', concatenate without 'model_level' dimension
+        dataarray_list = [
+            dataarray.squeeze(dim='model_level').drop_vars(['model_level'])
+            if 'model_level' in dataarray.dims
+            else dataarray
+            for dataarray in dataarray_list
+        ]
+        # assign coordinate with last dataarray to fix 1) use 360 degree system issue 2) slightly different lat lons
+        dataarray_list = [
+            dataarray.assign_coords(dataarray_list[-1].coords) 
+            for dataarray in dataarray_list
+        ]
+        data = xr.merge(dataarray_list)
+
+        # unit conversion
+        # particulate matter: concentration * 10^9
+        # target unit is ug/m3
+        for var in ['pm2p5', 'pm10']:
+            data[var].values = data[var].values * (10 ** 9)
+        # other: concentration x pressure / (287.058 * temp) * 10^9
+        # target unit is ug/m3
+        for var in ['co', 'no2', 'go3', 'so2']:
+            data[var].values = data[var].values * data['msl'].values / (287.058 * data['t2m'].values) * (10 ** 9)
+
+        # drop pressure and temperature
+        data = data.drop_vars(['msl', 't2m'])
+        # xarray.Dataset to xarray.DataArray
+        data = data.to_array()
+
+        # Remove local files
+        os.remove('cams_download.zip')
+        try:  # Workaround for elusive permission error
+            for nc_file in os.listdir(fname):
+                os.remove(f'{fname}/{nc_file}')
+            os.rmdir(fname)
+        except:
+            pass
+
+        centerlat, centerlon = (min_lat + max_lat) / 2, (min_lon + max_lon) / 2
+        return data.sel(latitude=centerlat, longitude=centerlon, method="nearest")

tests/test_layers.py

@@ -5,6 +5,7 @@
     AlosDSM,
     AverageNetBuildingHeight,
     BuiltUpHeight,
+    Cams,
     Era5HottestDay,
     EsaWorldCover,
     EsaWorldCoverClass,
@@ -48,6 +49,11 @@ def test_built_up_height():
     data = BuiltUpHeight().get_data(BBOX)
     assert np.size(data) > 0
 
+@pytest.mark.skip(reason="CDS API needs personal access token file to run")
+def test_cams():
+    data = Cams().get_data(BBOX)
+    assert np.size(data) > 0
+
 @pytest.mark.skip(reason="CDS API needs personal access token file to run")
 def test_era_5_hottest_day():
     data = Era5HottestDay().get_data(BBOX)