reflect_loss_beckmann Class Reference
[Ocean Boundaries]

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Detailed Description

Models ocean surface reflection loss using Beckmann-Spizzichino model.

Jones et. al. has shown that this model can be broken into high and low frequency components. The high frequency component is given by:

\[ RL_{high} = -20 \: log_{10} \left( \sqrt{1-v_3} \right) \]

\[ v_3 = max \left( \frac{1}{2} sin \theta, \left[ 1 - \frac{ exp(-a \theta^2 / 4 ) }{ \sqrt{ \pi a \theta^2 } } \right] sin \theta \right) \]

where $ a = \frac{1}{ 2 ( 0.003 + 5.1x10^{-3} w ) } $, $ w $ = wind speed (m/sec), and $ v_3 $ is limited to a 0.99 value. Note that the high frequency component is frequency independent. The low frequency component is given by:

\[ RL_{1ow} = -20 \: log_{10} \left( 0.3 + \frac{0.7}{1+6.0x10^{-11} w^4 f^2 } \right) \]

where $ f $ = signal frequency (Hz). Note that the low frequency component is grazing angle independent. The total reflection loss is the sum of these two terms in dB.

References:
Adrian D. Jones, Janice Sendt, Alec J. Duncan, Paul A. Clarke and Amos Maggi, "Modelling the acoustic reflection loss at the rough ocean surface," Proceedings of ACOUSTICS 2009, Australian Acoustical Society, 23-25 November 2009, Adelaide, Australia.

Constructor & Destructor Documentation

reflect_loss_beckmann ( double  wind_speed  )  [inline]

Initializes ocean surface reflection loss using using Beckmann-Spizzichino model.

Parameters:
wind_speed Wind_speed used to develop rough seas (m/s).

Member Function Documentation

void reflect_loss ( const wposition1 location,
const seq_vector frequencies,
double  angle,
vector< double > *  amplitude,
vector< double > *  phase = NULL 
) [virtual]

Computes the broadband reflection loss and phase change.

Parameters:
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.


Member Data Documentation

const double _wind_speed [private]

Wind speed (m/sec).


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