Allow for particle longitude to be any value

* Particle longitude and grid longitudes are re-mapped to [-180,180)
  inside the curvilinear particle in cell check method.
* Depending on the proximity of the particle to +/- 180, cell corners
  are adjusted to the image position that is closest to the particle.

Author: fluidnumericsJoe

src/parcels/_core/index_search.py

@@ -102,12 +102,22 @@ 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]])
+    # Map grid and particle longitudes to [-180,180)
+    px = ((px + 180.0) % 360.0) - 180.0
+    x = ((x + 180.0) % 360.0) - 180.0
+
+    # Create a mask for antimeridian cells
     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
+
+    if np.any(antimeridian_cell):
+        # For any antimeridian cell ...
+        #  If particle longitude is closer to 180.0, then negative cell longitudes need to be bumped by +360
+        mask = (px < 0.0) & antimeridian_cell[np.newaxis, :] & (x[np.newaxis, :] > 0.0)
+        px[mask] += 360.0
+        #  If particle longitude is closer to -180.0, then positive cell longitudes need to be bumped by -360
+        mask = (px > 0.0) & antimeridian_cell[np.newaxis, :] & (x[np.newaxis, :] < 0.0)
+        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]])