diff --git a/cost_function.py b/cost_function.py
index b8a349893e062d8e753cfd807da453de8b7aa2e7..f32cefcf361a01992c46a0fdd8196a5ee8e05d29 100755
--- a/cost_function.py
+++ b/cost_function.py
@@ -56,13 +56,11 @@ def calculate_radii_rossby(list_eddies, e_overestim, handlers, array_d_init):
 
         if (V_max < 100):
             # calculate Ro and Delta_Ro
-            Ro = V_max / (f * R_Vmax)
+            rossby += V_max / (f * R_Vmax)
         else:
-            Ro = 0
             days_modifier += 1
 
         radii += R_Vmax # in m
-        rossby += Ro
 
     return {"radii": radii, "rossby": rossby, "days_modifier": days_modifier}