Filters
This module contains the functions associated with filters needed for numerical stability.
- SWAMPE.filters.diffusion(Ximn, sigma)
Applies the diffusion filter described in Gelb and Gleeson (eq. 12).
- Parameters
Ximn (list) – the spectral coefficient data to be filtered
sigma (float) – the hyperviscosity coefficient
- Return newXimn
filtered spectral coefficient
- Return type
array of float
- SWAMPE.filters.modal_splitting(Xidataslice, alpha)
Applies the modal splitting filter from Hack and Jacob (1992).
- Parameters
Xidata (list) – data array to be filtered
alpha (float) – filter coefficient
- Return newxi
filtered data slice
- Return type
array of float
- SWAMPE.filters.sigma(M, N, K4, a, dt)
Computes the coefficient for the fourth degree diffusion filter described in Gelb and Gleeson (eq. 12) for vorticity and divergence.
Parameters
- param M
spectral dimension
- type M
int
- param N
highest degree of associated Legendre polynomials
- type N
int
- param K4
hyperviscosity coefficient
- type K4
float
- param a
planetary radius, m
- type a
float
- param dt
time step,s
- type dt
float
Returns
- return sigma
coefficient for the diffusion filter for geopotential
- rtype
array of float
- SWAMPE.filters.sigma6(M, N, K4, a, dt)
Computes the coefficient for the sixth degree diffusion filter for vorticity and divergence.
- Parameters
M (int) – spectral dimension
N (int) – highest degree of associated Legendre polynomials
K4 (float64) – hyperviscosity coefficient
a (float64) – planetary radius, m
dt (float64) – time step,s
- Return sigma
coefficient for the diffusion filter for geopotential
- Return type
array of float64
- SWAMPE.filters.sigma6Phi(M, N, K4, a, dt)
Computes the coefficient for the fourth degree diffusion Filter described in Gelb and Gleeson (eq. 12) for geopotential.
- Parameters
M (int) – spectral dimension
N (int) – highest degree of associated Legendre polynomials
K4 (float) – hyperviscosity coefficient
a (float) – planetary radius, m
dt (float) – time step,s
- Return sigma
coefficient for the diffusion filter for geopotential
- Return type
array of float
- SWAMPE.filters.sigmaPhi(M, N, K4, a, dt)
Computes the coefficient for the fourth degree diffusion Filter described in Gelb and Gleeson (eq. 12) for geopotential.
- Parameters
M (int) – spectral dimension
N (int) – highest degree of associated Legendre polynomials
K4 (float) – hyperviscosity coefficient
a (float) – planetary radius, m
dt (float) – time step,s
- Return sigma
coefficient for the diffusion filter for geopotential
- Return type
array of float