pyPDAF.PDAF.generate_obs

pyPDAF.PDAF.generate_obs()

Generation of synthetic observations based on given error statistics and observation operator.

When diagonal observation error covariance matrix is used, it is recommended to use pyPDAF.PDAF.omi_generate_obs() functionalities for fewer user-supplied functions and improved efficiency.

The generated synthetic observations are based on each member of model forecast. Therefore, an ensemble of observations can be obtained. In a typical experiment, one may only need one ensemble member. The implementation strategy is similar to an assimilation step. This means that, one can reuse many user-supplied functions for assimilation and observation generation.

The function is a combination of pyPDAF.PDAF.put_state_generate_obs() and pyPDAF.PDAF.get_state().

This function executes the user-supplied function in the following sequence:

1. py__collect_state_pdaf

2. py__prepoststep_state_pdaf

3. py__init_dim_obs_pdaf

4. py__obs_op_pda

5. py__init_obserr_f_pdaf

6. py__get_obs_f_pdaf

7. py__prepoststep_state_pdaf

8. py__distribute_state_pdaf

9. py__next_observation_pdaf

Parameters:

• py__collect_state_pdaf (Callable[dim_p:int, state_p : ndarray[tuple[dim_p], np.float64]]) –

  Routine to collect a state vector

  Callback Parameters

  • dim_pint

    • pe-local state dimension

  • state_pndarray[tuple[dim_p], np.float64]

    • local state vector

  Callback Returns

  • state_pndarray[tuple[dim_p], np.float64]

    • local state vector

• py__distribute_state_pdaf (Callable[dim_p:int, state_p : ndarray[tuple[dim_p], np.float64]]) –

  Routine to distribute a state vector

  Callback Parameters

  • dim_pint

    • pe-local state dimension

  • state_pndarray[tuple[dim_p], np.float64]

    • local state vector

  Callback Returns

  • state_pndarray[tuple[dim_p], np.float64]

    • local state vector

• py__init_dim_obs_pdaf (Callable[step:int, dim_obs_p:int]) –

  Initialize dimension of observation vector

  Callback Parameters

  • stepint

    • current time step

  • dim_obs_pint

    • dimension of observation vector

  Callback Returns

  • dim_obs_pint

    • dimension of observation vector

• py__obs_op_pdaf (Callable[step:int, dim_p:int, dim_obs_p:int, state_p : ndarray[tuple[dim_p], np.float64], m_state_p : ndarray[tuple[dim_obs_p], np.float64]]) –

  Observation operator

  Callback Parameters

  • stepint

    • Current time step

  • dim_pint

    • Size of state vector (local part in case of parallel decomposed state)

  • dim_obs_pint

    • Size of observation vector

  • state_pndarray[tuple[dim_p], np.float64]

    • Model state vector

  • m_state_pndarray[tuple[dim_obs_p], np.float64]

    • Observed state vector (i.e. the result after applying the observation operator to state_p)

  Callback Returns

  • m_state_pndarray[tuple[dim_obs_p], np.float64]

    • Observed state vector (i.e. the result after applying the observation operator to state_p)

• py__get_obs_f_pdaf (Callable[step:int, dim_obs_f:int, observation_f : ndarray[tuple[dim_obs_f], np.float64]]) –

  Provide observation vector to user

  Callback Parameters

  • stepint

    • Current time step

  • dim_obs_fint

    • Size of the full observation vector

  • observation_fndarray[tuple[dim_obs_f], np.float64]

    • Full vector of synthetic observations (process-local)

  Callback Returns

  • observation_fndarray[tuple[dim_obs_f], np.float64]

    • Full vector of synthetic observations (process-local)

• py__init_obserr_f_pdaf (Callable[step:int, dim_obs_f:int, obs_f : ndarray[tuple[dim_obs_f], np.float64], obserr_f : ndarray[tuple[dim_obs_f], np.float64]]) –

  Initialize vector of observation error standard deviations

  Callback Parameters

  • stepint

    • Current time step

  • dim_obs_fint

    • Full dimension of observation vector

  • obs_fndarray[tuple[dim_obs_f], np.float64]

    • Full observation vector

  • obserr_fndarray[tuple[dim_obs_f], np.float64]

    • Full observation error stddev

  Callback Returns

  • obserr_fndarray[tuple[dim_obs_f], np.float64]

    • Full observation error stddev

• py__prepoststep_pdaf (Callable[step:int, dim_p:int, dim_ens:int, dim_ens_p:int, dim_obs_p:int, state_p : ndarray[tuple[dim_p], np.float64], uinv : ndarray[tuple[dim_ens-1, dim_ens-1], np.float64], ens_p : ndarray[tuple[dim_p, dim_ens], np.float64], flag:int]) –

  User supplied pre/poststep routine

  Callback Parameters

  • stepint

    • current time step (negative for call after forecast)

  • dim_pint

    • pe-local state dimension

  • dim_ensint

    • size of state ensemble

  • dim_ens_pint

    • pe-local size of ensemble

  • dim_obs_pint

    • pe-local dimension of observation vector

  • state_pndarray[tuple[dim_p], np.float64]

    • pe-local forecast/analysis state (the array ‘state_p’ is not generally not initialized in the case of seik. it can be used freely here.)

  • uinvndarray[tuple[dim_ens-1, dim_ens-1], np.float64]

    • inverse of matrix u

  • ens_pndarray[tuple[dim_p, dim_ens], np.float64]

    • pe-local state ensemble

  • flagint

    • pdaf status flag

  Callback Returns

  • state_pndarray[tuple[dim_p], np.float64]

    • pe-local forecast/analysis state (the array ‘state_p’ is not generally not initialized in the case of seik. it can be used freely here.)

  • uinvndarray[tuple[dim_ens-1, dim_ens-1], np.float64]

    • inverse of matrix u

  • ens_pndarray[tuple[dim_p, dim_ens], np.float64]

    • pe-local state ensemble

• py__next_observation_pdaf (Callable[stepnow:int, nsteps:int, doexit:int, time:float]) –

  Provide time step and time of next observation

  Callback Parameters

  • stepnowint

    • number of the current time step

  • nstepsint

    • number of time steps until next obs

  • doexitint

    • whether to exit forecasting (1 for exit)

  • timefloat

    • current model (physical) time

  Callback Returns

  • nstepsint

    • number of time steps until next obs

  • doexitint

    • whether to exit forecasting (1 for exit)

  • timefloat

    • current model (physical) time

Returns:

flag – Status flag

Return type:

int