1. Parameters module

This module defines the parameters for the model.

Note

The python code is available here : params_maooam.py .

Example:
>>> from params_maooam import ndim,natm,noc
>>> from params_maooam import oms,nboc,ams,nbatm
>>> from params_maooam import *

There are three types of parameters :

  • integration parameters : simulation time (transient and effective), time step, writeout and write step time
  • dimensional parameters : dimensions of the truncation of fourier for the atmosphere and the ocean
  • physical parameters : they are used in the tensor for the integration

1.1. Integration parameters

Warning

Time is adimensional. If t_real is in seconds, then t_model = t_real * f_0 where f_0 is the Coriolis parameter at 45 degrees latitude ( 1.032e-4 )

  • t_trans : the transient simulation time of the model to be on the attractor. The states vectors are not written on evol_field.dat.
  • t_run : the running simulation time of the model. The states vectors are written on evol_field.dat every tw.
  • dt : the step time.
  • writeout : boolean value to decide if the module produces evol_field.dat.
  • tw : the step time to write on evol_field.
  • f2py : boolean to activate the f2py optimization.

1.2. Dimensional parameters

  • oms and ams : the matrices that gives the possible values of the modes Nx and Ny.
  • nboc and natm : the numbers of oceanic and atmospheric blocs.
  • natm and noc : the numbers of functions available.
  • ndim : the total dimension.
Example:
>>> oms =get_modes(2,4)# ocean mode selection
>>> ams =get_modes(2,2)# atmosphere mode selection
>>> nboc,nbatm = 2*4,2*2      # number of blocks
>>> (natm,noc,ndim)=init_params(nboc,nbatm)
>>>
>>> # Oceanic blocs
>>> #( x block number accounts for half-integer wavenumber e.g 1    => 1/2 , 2 => 1, etc...)
>>> OMS[0,:] = 1,1
>>> OMS[1,:] = 1,2
>>> OMS[2,:] = 1,3
>>> OMS[3,:] = 1,4
>>> OMS[4,:] = 2,1
>>> OMS[5,:] = 2,2
>>> OMS[6,:] = 2,3
>>> OMS[7,:] = 2,4
>>> #Atmospheric blocs
>>> AMS[0,:] = 1,1
>>> AMS[1,:] = 1,2
>>> AMS[2,:] = 2,1
>>> AMS[3,:] = 2,2
Typical dimensional parameters:
 
  • atmosphere 2x,2y ; ocean 2x,4y ; ndim = 36
  • atmosphere 2x,2y ; ocean 4x,4y ; ndim = 52
  • atmosphere 2x,4y ; ocean 2x,4y ; ndim = 56

1.3. Physical parameters

Some defaut parameters are presented below. Some parameters files related to already published article are available in the params folder.

1.3.1. Scale parameters

  • scale = 5.e6 : characteristic space scale, L*pi
  • f0 = 1.032e-4 : Coriolis parameter at 45 degrees latitude
  • n = 1.5e0 : aspect ratio (n = 2Ly/Lx ; Lx = 2*pi*L/n; Ly = pi*L)
  • rra = 6370.e3 : earth radius
  • phi0_npi = 0.25e0 : latitude exprimed in fraction of pi

1.3.2. Parameters for the ocean

  • gp = 3.1e-2 : reduced gravity
  • r = 1.e-8 : frictional coefficient at the bottom of the ocean
  • h = 5.e2 : depth of the water layer of the ocean
  • d = 1.e-8 : the coupling parameter (should be divided by f0 to be adim)

1.3.3. Parameters for the atmosphere

  • k = 0.02 : atmosphere bottom friction coefficient
  • kp = 0.04 : atmosphere internal friction coefficient
  • sig0 = 0.1e0 : static stability of the atmosphere

1.3.7. Key values

  • k is the friction coefficient at the bottom of the atmosphere. Typical values are 0.01 or 0.0145 for chaotic regimes.
  • kp is the internal friction between the atmosphere layers. kp=2*k
  • d is the friction coefficient between the ocean and the atmosphere. Typical values are 6*10^{-8} s^{-1} or 9*10^{-8} s^{-1}.
  • lambda is the heat exchange between the ocean and the atmosphere. Typical values are 10 W m^{-2} K^{-1} or 15.06 W m ^{-2} K^{-1}.

1.4. Dependencies

>>> import numpy as np

1.5. Fonctions

Here are the functions to generate the parameters.

params_maooam.get_modes(nxmax, nymax)[source]

Computes the matrix oms and ams with nxmax and nymax

params_maooam.init_params(nboc, nbatm)[source]

Computes the dimensions of the system