def okubo(u,v,pm,pn):
'''
Compute the Okubo-Weiss parameter
'''
Mp,Lp=pm.shape
L=Lp-1
M=Mp-1
Lm=L-1
Mm=M-1
uom = 2.*u/(pm[:,:L]+pm[:,1:Lp])
uon = 2.*u/(pn[:,:L]+pn[:,1:Lp])
von = 2.*v/(pn[0:M,:]+pn[1:Mp,:])
vom = 2.*v/(pm[0:M,:]+pm[1:Mp,:])
mn=pm*pn
mn_p=(mn[:M,:L]+mn[:M,1:Lp]+mn[1:Mp,1:Lp]+mn[1:Mp,:L])/4.
# relative vorticity:
xi=mn*rt.psi2rho(von[:,1:Lp]-von[:,:L]-uom[1:Mp,:]+uom[:M,:])
# Sigma_T:
ST=mn*rt.psi2rho(von[:,1:Lp]-von[:,:L]+uom[1:Mp,:]-uom[:M,:])
# Sigma_N:
SN=np.ma.zeros((Mp,Lp),u.dtype)
SN[1:-1,1:-1]=mn[1:-1,1:-1]*(uon[1:-1,1:]
-uon[1:-1,:-1]
-vom[1:,1:-1]
+vom[:-1,1:-1])
return SN**2+ST**2-xi**2
def okubo(u, v, pm, pn):
'''
Compute the Okubo-Weiss parameter
'''
Mp, Lp = pm.shape
L = Lp - 1
M = Mp - 1
Lm = L - 1
Mm = M - 1
uom = 2. * u / (pm[:, :L] + pm[:, 1:Lp])
uon = 2. * u / (pn[:, :L] + pn[:, 1:Lp])
von = 2. * v / (pn[0:M, :] + pn[1:Mp, :])
vom = 2. * v / (pm[0:M, :] + pm[1:Mp, :])
mn = pm * pn
mn_p = (mn[:M, :L] + mn[:M, 1:Lp] + mn[1:Mp, 1:Lp] + mn[1:Mp, :L]) / 4.
# relative vorticity:
xi = mn * rt.psi2rho(von[:, 1:Lp] - von[:, :L] - uom[1:Mp, :] + uom[:M, :])
# Sigma_T:
ST = mn * rt.psi2rho(von[:, 1:Lp] - von[:, :L] + uom[1:Mp, :] - uom[:M, :])
# Sigma_N:
SN = np.ma.zeros((Mp, Lp), u.dtype)
SN[1:-1, 1:-1] = mn[1:-1, 1:-1] * (uon[1:-1, 1:] - uon[1:-1, :-1] -
vom[1:, 1:-1] + vom[:-1, 1:-1])
return SN**2 + ST**2 - xi**2
def vorticity(u, v, pm, pn):
'''
Compute the relative vorticity
'''
Mp, Lp = pm.shape
L = Lp - 1
M = Mp - 1
Lm = L - 1
Mm = M - 1
uom = 2. * u / (pm[:, :L] + pm[:, 1:Lp])
uon = 2. * u / (pn[:, :L] + pn[:, 1:Lp])
von = 2. * v / (pn[0:M, :] + pn[1:Mp, :])
vom = 2. * v / (pm[0:M, :] + pm[1:Mp, :])
mn = pm * pn
mn_p = (mn[:M, :L] + mn[:M, 1:Lp] + mn[1:Mp, 1:Lp] + mn[1:Mp, :L]) / 4.
# relative vorticity:
xi = mn * rt.psi2rho(von[:, 1:Lp] - von[:, :L] - uom[1:Mp, :] + uom[:M, :])
return xi
def vorticity(u,v,pm,pn): ''' Compute the relative vorticity ''' Mp,Lp=pm.shape L=Lp-1 M=Mp-1 Lm=L-1 Mm=M-1 uom = 2.*u/(pm[:,:L]+pm[:,1:Lp]) uon = 2.*u/(pn[:,:L]+pn[:,1:Lp]) von = 2.*v/(pn[0:M,:]+pn[1:Mp,:]) vom = 2.*v/(pm[0:M,:]+pm[1:Mp,:]) mn=pm*pn mn_p=(mn[:M,:L]+mn[:M,1:Lp]+mn[1:Mp,1:Lp]+mn[1:Mp,:L])/4. # relative vorticity: xi=mn*rt.psi2rho(von[:,1:Lp]-von[:,:L]-uom[1:Mp,:]+uom[:M,:]) return xi
