Volume attenuation in the ocean has a chemical nature,
and it is induced by relaxation processes of salt constituents like MgSO, B(OH) and MgCO.
The factor is given by the decaying exponential

(4.4) 
where is the ray arclength and
is the Thorpe (frequency dependent) attenuation coefficient in dB/m,
given by[2]

(4.5) 
with the frequency given in kHz.
Orlando Camargo Rodríguez
20120621