Adjust longitudes for antimeridian cells to account for periodicity

Author: fluidnumericsJoe

src/parcels/_core/index_search.py

@@ -102,6 +102,13 @@ def curvilinear_point_in_cell(grid, y: np.ndarray, x: np.ndarray, yi: np.ndarray
     )
 
     px = np.array([grid.lon[yi, xi], grid.lon[yi, xi + 1], grid.lon[yi + 1, xi + 1], grid.lon[yi + 1, xi]])
+    lon_span = px.max(axis=0) - px.min(axis=0)
+    antimeridian_cell = lon_span > 180.0
+    # For any antimeridian cell, bump the positive longitudes by 360 degrees
+    # This only works if particle longitudes are always gauranteed to be less than 180 degreeds
+    mask = (px > 0.0) & antimeridian_cell[np.newaxis, :]
+    px[mask] -= 360.0
+
     py = np.array([grid.lat[yi, xi], grid.lat[yi, xi + 1], grid.lat[yi + 1, xi + 1], grid.lat[yi + 1, xi]])
 
     a, b = np.dot(invA, px), np.dot(invA, py)
@@ -119,7 +126,6 @@ def curvilinear_point_in_cell(grid, y: np.ndarray, x: np.ndarray, yi: np.ndarray
             ((y - py[0]) / (py[1] - py[0]) + (y - py[3]) / (py[2] - py[3])) * 0.5,
             (x - a[0] - a[2] * eta) / (a[1] + a[3] * eta),
         )
-
     is_in_cell = np.where((xsi >= 0) & (xsi <= 1) & (eta >= 0) & (eta <= 1), 1, 0)
 
     return is_in_cell, np.column_stack((xsi, eta))