Adding unit test for checking croco_from_z_to_sigma function

Author: erikvansebille

tests/test_advection.py

@@ -195,6 +195,45 @@ def test_advection_RK45(lon, lat, mode, rk45_tol):
     print(fieldset.RK45_tol)
 
 
+def test_conversion_3DCROCO():
+    """Test of the (SciPy) version of the conversion from depth to sigma in CROCO
+
+    Values below are retrieved using xroms and hardcoded in the method (to avoid dependency on xroms):
+    # x, y = 10, 20
+    # s_xroms = ds.s_w.values
+    # z_xroms = ds.z_w.isel(time=0).isel(eta_rho=y).isel(xi_rho=x).values
+    # lat, lon = ds.y_rho.values[y, x], ds.x_rho.values[y, x]
+    """
+    fieldset = FieldSet.from_modulefile(TEST_DATA / "fieldset_CROCO3D.py")
+
+    lat, lon = 78000.0, 38000.0
+    s_xroms = np.array([-1.0, -0.9, -0.8, -0.7, -0.6, -0.5, -0.4, -0.3, -0.2, -0.1, 0.0], dtype=np.float32)
+    z_xroms = np.array(
+        [
+            -1.26000000e02,
+            -1.10585846e02,
+            -9.60985413e01,
+            -8.24131317e01,
+            -6.94126511e01,
+            -5.69870148e01,
+            -4.50318756e01,
+            -3.34476166e01,
+            -2.21383114e01,
+            -1.10107975e01,
+            2.62768921e-02,
+        ],
+        dtype=np.float32,
+    )
+
+    sigma = np.zeros_like(z_xroms)
+    from parcels.field import _croco_from_z_to_sigma_scipy
+
+    for zi, z in enumerate(z_xroms):
+        sigma[zi] = _croco_from_z_to_sigma_scipy(fieldset, 0, z, lat, lon, None)
+
+    assert np.allclose(sigma, s_xroms, atol=1e-3)
+
+
 @pytest.mark.parametrize("mode", ["scipy", "jit"])
 def test_advection_3DCROCO(mode):
     fieldset = FieldSet.from_modulefile(TEST_DATA / "fieldset_CROCO3D.py")