Models ocean surface reflection loss using Eckart's model.
where = wave number (1/m),
= signal frequency (Hz),
= speed of sound (m/sec),
= RMS height of wave spectrum (m),
= grazing angle (rad),
= Rayleigh roughness parameter, and
= reflection loss (dB). Eckart's model arises from a Kirchhoff approximation to scattering and the assumption of a Gaussian probability of surface elevations of standard deviation h.
Jones et. al. has shown that many of the terms in this expression can be simplified if we assume that the speed of sound is 1500 m/s and that the wave height is related to wind speed by a Pierson-Moskowitz spectrum for fully developed, wind driven seas.
where = wind speed (m/sec).
reflect_loss_eckart | ( | double | wind_speed | ) | [inline] |
Initializes ocean surface reflection loss using Eckart's model.
wind_speed | Wind_speed used to develop rough seas (m/s) |
virtual void reflect_loss | ( | const wposition1 & | location, | |
const seq_vector & | frequencies, | |||
double | angle, | |||
vector< double > * | amplitude, | |||
vector< double > * | phase = NULL | |||
) | [inline, virtual] |
Computes the broadband reflection loss and phase change.
location | Location at which to compute reflection loss. | |
frequencies | Frequencies over which to compute loss. (Hz) | |
angle | Grazing angle relative to the interface (radians). | |
amplitude | Change in ray intensity in dB (output). | |
phase | Change in ray phase in radians (output). Hard-coded to a value of PI for this model. Phase change not computed if this is NULL. |
Implements reflect_loss_model.
const double _wind_speed2 [private] |
Wind speed squared (m/sec)^2.