fmi_parameters function

Create reference model reference parameter catalogue

In order to run the fluvial model inversion (FMI) routine, a set of randomised target parameter combinations needs to be created. This function does this job.

fmi_parameters(
  n,
  d_s,
  s_s,
  r_s,
  q_s,
  h_w,
  w_w,
  a_w,
  f_min,
  f_max,
  r_0,
  f_0,
  q_0,
  v_0,
  p_0,
  e_0,
  n_0_a,
  n_0_b,
  res
)

Arguments

• n: Numeric value, number of output reference spectra.
• d_s: Numeric value, mean sediment grain diameter (m). Alternative to gsd.
• s_s: Numeric value, standard deviation of sediment grain diameter (m). Alternative to gsd.
• r_s: Numeric value, specific sediment density (kg / m^3)
• q_s: Numeric value, unit sediment flux (m^2 / s)
• h_w: Numeric value, fluid flow depth (m)
• w_w: Numeric value, fluid flow width (m)
• a_w: Numeric value, fluid flow inclination angle (radians)
• f_min: Numeric value, lower boundary of the frequency range to be modelled.
• f_max: Numeric value, upper boundary of the frequency range to be modelled.
• r_0: Numeric value, distance of seismic station to source
• f_0: Numeric value, reference frequency (Hz)
• q_0: Numeric value, ground quality factor at f_0. "Reasonable value may be 20" (Tsai et al. 2012).
• v_0: Numeric value, phase speed of the Rayleigh wave at f_0 (m/s). Assuming a shear wave velocity of about 2200 m/s, Tsai et al. (2012) yield a value of 1295 m/s for this parameter.
• p_0: Numeric value, variation exponent of Rayleigh wave velocities with frequency (dimensionless)
• e_0: Numeric value, exponent characterizing quality factor increase with frequency (dimensionless). "Reasonable value may be 0" (Tsai et al. 2012).
• n_0_a: Numeric value, lower Greens function displacement amplitude coefficients. Cf. N_ij in eq. 36 in Gimbert et al. (2014)
• n_0_b: Numeric value, lower Greens function displacement amplitude coefficients. Cf. N_ij in eq. 36 in Gimbert et al. (2014)
• res: Numeric value, output resolution, i.e. length of the spectrum vector.

Returns

List object with model reference parameters.

Details

All parameters must be provided as single values, except for those parameters that shall be randomised, which must be provided as a vector of length two. This vector defines the range within which uniformly distributed random values will be generated and assigned.

Examples

## create two parameter sets where h_w (water level) and q_s (sediment
## flux) are randomly varied.

ref_pars <- fmi_parameters(n = 2,
                           h_w = c(0.02, 2.00),
                           q_s = c(0.001, 50.000) / 2650,
                           d_s = 0.01,
                           s_s = 1.35,
                           r_s = 2650,
                           w_w = 6,
                           a_w = 0.0075,
                           f_min = 5,
                           f_max = 80,
                           r_0 = 6,
                           f_0 = 1,
                           q_0 = 10,
                           v_0 = 350,
                           p_0 = 0.55,
                           e_0 = 0.09,
                           n_0_a = 0.6,
                           n_0_b = 0.8,
                           res = 100)

Author(s)

Michael Dietze