Mini project

tools.py

+import matplotlib.pylab as plt
+import netCDF4
+import numpy as np
+import netCDF4 as nc
+
+def mod_arr(field,axis,order):
+    """Define array with boundary conditions to compute partial derivatives for first order forward scheme. 
+    Boundary condition for last row or column:N=N+(N-(N-1)) of field array
+    • Field: field to derive (array to modify)
+    • axis = 1, colums varies (used to compute derivates along x). axis = 0 rows varies (used to compute derivates along y) 
+    • order=order of precision of derivatives"""
+    if order==1:
+        mod_arr=np.roll(field,-1,axis=axis)
+        if axis==0:
+            mod_arr[-1,:]=2*field[-1,:]-field[-2,:]
+        elif axis==1: 
+            mod_arr[:,-1]=2*field[:,-1]-field[:,-2]
+    return mod_arr
+
+
+def derivatives(field1,field2,axis,order):
+    """Compute partial derivatives along a field called field2 which could be in time or space using first-order forward scheme
+    • Field1: Field to derive
+    • Field2: Field to derive from
+    • axis: along which derivation is carried out.
+    axis=1 derivation along i direction, axis=0 derivation along j direction
+    • order= order of precision of derivatives, this function can be expanded to a higher order of precision"""
+    if order==1:
+        der=np.divide((mod_arr(field1,axis,order)-field1),(mod_arr(field2,axis,order)-field2))
+    return der
+