diff --git a/pyaerocom/colocation/colocated_data.py b/pyaerocom/colocation/colocated_data.py
index c9ec07c6e..e2d983bd1 100644
--- a/pyaerocom/colocation/colocated_data.py
+++ b/pyaerocom/colocation/colocated_data.py
@@ -34,19 +34,18 @@
 logger = logging.getLogger(__name__)
 
 
-def ensure_correct_dimensions(data: np.ndarray | xr.DataArray):
+def ensure_correct_dimensions(data: xr.DataArray):
     """
-    Ensure the dimensions on either a numpy aray or xarray passed to ColocatedData.
+    Ensure the dimensions on an xarray.DataArray passed to ColocatedData.
     If a ColocatedData object is created outside of pyaerocom, this checking is needed.
     This function is used as part of the model validator.
     """
-    shape = data.shape[0]
-    if isinstance(data, np.ndarray):
-        num_dims = data.ndim
-    elif isinstance(data, xr.DataArray):
-        num_dims = len(data.dims)
-    else:
+    if not isinstance(data, xr.DataArray):
         raise ValueError("Could not interpret data")
+
+    shape = data.shape[0]
+    num_dims = len(data.dims)
+
     if num_dims not in (2, 3, 4):
         raise DataDimensionError("invalid input, need 2D, 3D or 4D numpy array")
     elif not shape == 2:
@@ -124,19 +123,19 @@ class ColocatedData(BaseModel):
 
     @model_validator(mode="after")
     def validate_data(self):
+        if self.data is None:
+            return self
         if isinstance(self.data, Path):
             # make sure path is str instance
             self.data = str(self.data)
         if isinstance(self.data, str):
-            assert self.data.endswith("nc"), ValueError(
-                "Invalid data filepath str, must point to a .nc file"
-            )
+            if not self.data.endswith("nc"):
+                raise ValueError(
+                    f"Invalid data filepath str, must point to a .nc file. Got {self.data}"
+                )
             self.open(self.data)
-        elif isinstance(self.data, xr.DataArray):
-            ensure_correct_dimensions(self.data)
-            return self.data
-        elif isinstance(self.data, np.ndarray):
-            ensure_correct_dimensions(self.data)
+            return self
+        if isinstance(self.data, np.ndarray):
             if hasattr(self, "model_extra"):
                 da_keys = dir(xr.DataArray)
                 extra_args_from_class_initialization = {
@@ -146,6 +145,9 @@ def validate_data(self):
                 extra_args_from_class_initialization = {}
             data = xr.DataArray(self.data, **extra_args_from_class_initialization)
             self.data = data
+        # self.data should be xr.DataArray at this stage
+        ensure_correct_dimensions(self.data)
+        return self
 
     # Override __init__ to allow for positional arguments
     def __init__(
diff --git a/pyaerocom/colocation/colocation_setup.py b/pyaerocom/colocation/colocation_setup.py
index ed74838cc..d0703f18d 100644
--- a/pyaerocom/colocation/colocation_setup.py
+++ b/pyaerocom/colocation/colocation_setup.py
@@ -479,6 +479,7 @@ def validate_no_forbidden_keys(self):
         for key in self.FORBIDDEN_KEYS:
             if key in self.model_fields:
                 raise ValidationError
+        return self
 
     @cached_property
     def basedir_logfiles(self):
@@ -488,25 +489,26 @@ def basedir_logfiles(self):
         return str(p)
 
     @model_validator(mode="after")
-    @classmethod
-    def validate_obs_config(cls, v: PyaroConfig):
-        if v is not None and cls.obs.config.name != cls.obs_id:
+    def validate_obs_config(self):
+        if self.obs_config is None:
+            return self
+        if self.obs_config.name != self.obs_id:
             logger.info(
-                f"Data ID in Pyaro config {v.name} does not match obs_id {cls.obs_id}. Setting Pyaro config to None!"
+                f"Data ID in Pyaro config {self.obs_config.name} does not match obs_id {self.obs_id}. Setting Pyaro config to None!"
             )
-            v = None
-        if v is not None:
-            if isinstance(v, dict):
+            self.obs_config = None
+        if self.obs_config is not None:
+            if isinstance(self.obs_config, dict):
                 logger.info("Obs config was given as dict. Will try to convert to PyaroConfig")
-                v = PyaroConfig(**v)
-            if v.name != cls.obs_id:
+                self.obs_config = PyaroConfig(**self.obs_config)
+            if self.obs_config.name != self.obs_id:
                 logger.info(
-                    f"Data ID in Pyaro config {v.name} does not match obs_id {cls.obs_id}. Setting Obs ID to match Pyaro Config!"
+                    f"Data ID in Pyaro config {self.obs_config.name} does not match obs_id {self.obs_id}. Setting Obs ID to match Pyaro Config!"
                 )
-                cls.obs_id = v.name
-            if cls.obs_id is None:
-                cls.obs_id = v.name
-        return v
+                self.obs_id = self.obs_config.name
+            if self.obs_id is None:
+                self.obs_id = self.obs_config.name
+        return self
 
     def add_glob_meta(self, **kwargs):
         """
diff --git a/tests/io/test_readungridded.py b/tests/io/test_readungridded.py
index 7ffb7014e..8909d94af 100644
--- a/tests/io/test_readungridded.py
+++ b/tests/io/test_readungridded.py
@@ -58,9 +58,17 @@ def test_ReadUngridded___init__(data_ids, ignore_cache):
         (dict(station_name="La_Paz"), 1, 1),
         (dict(station_name=["La_Paz", "AAO*"]), 2, 2),
         (dict(altitude=[1000, 10000]), 3, 3),
-        (dict(altitude=[1000, 10000], ignore_station_names=dict(od550aer="La_Paz")), 2, 2),
+        (
+            dict(altitude=[1000, 10000], ignore_station_names=dict(od550aer="La_Paz")),
+            2,
+            2,
+        ),
         (dict(altitude=[1000, 10000], ignore_station_names="La_*"), 2, 2),
-        (dict(altitude=[1000, 10000], ignore_station_names=["La_*", "Mauna_Loa"]), 1, 1),
+        (
+            dict(altitude=[1000, 10000], ignore_station_names=["La_*", "Mauna_Loa"]),
+            1,
+            1,
+        ),
     ],
 )
 @pytest.mark.parametrize(